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Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim - Fixed #

Posted by Pete Mutlow on October 24, 2008, 9:00 pm
Message modified by board administrator December 16, 2009, 11:21 am

Hi All. Have this car to see on Monday (again) and on 1st visit 2 weeks ago the EML was showing PO170 - fuel trim. Emissions were all good and no faults found. Car drives well with no problems. Took light out and now it is back on. Vehicle is low mileage about 9000 miles and owned by a pensioner who doddles about in it. Memory thinks high positive fuel trim at about 25 which I take to be running lean. May be wrong on that but will check detail on Monday. Now here's the thing. I can remember seeing 3 of these in the past year with exactly the same code but no running problems. On each occaison, the pre cat 02 sensor was changed as a start and as I heard nothing more,assumed problem was solved. This gentleman is an old customer of mine and as a pensioner does not have money to spend on "possible" fixes. Would be grateful for any inputs to solve this problem.

Regards

Pete M

Re: Vauxhall Corsa 1000cc 2002

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on October 24, 2008, 9:08 pm, in reply to "Vauxhall Corsa 1000cc 2002"
Lee Mackintosh

The most common cause of this fault code is the mass air flow meter and this can also cause an 02 sensor code.

The +25% fuel trim is an indication of the ecu trying to correct the lean running condition and its reached its maximum fuelling adjustment for LTFT fuelling.

Others with more knowledge will be along later to correct me or explain it better.

Re: Vauxhall Corsa 1000cc 2002

Posted by Tony Sefton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5581' width='330' height='300' border=0 style='border:none;'> on October 24, 2008, 9:14 pm, in reply to "Vauxhall Corsa 1000cc 2002"
Tony Sefton

I would have 50p on it being an Air flow meter problem, ( especially at 6 years old )

Sit in the car let it idle and then give it full throttle, See how quick it responds, if its a bit stuttery or slugish revving up an AFM should cure it. ( this shows up on 1.0 models a lot easier than it does on 1.2 models for some reason ) And you will soon notice the difference after fitting a new AFM if it has cured it.

H.T.H. Tony.

P.S. Don't pay silly money for Dealer ones.

Re: Vauxhall Corsa 1000cc 2002

Posted by Gwyn Williams <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5354' width='330' height='300' border=0 style='border:none;'> on October 24, 2008, 10:03 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Gwyn Williams

And don't spend silly money on E Bay junk either!

Re: Vauxhall Corsa 1000cc 2002

Posted by Mark Lamont <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2555' width='330' height='300' border=0 style='border:none;'> on October 24, 2008, 10:17 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"

Hi Pete had same symptoms on an Agila recently, pensioner low mileage etc, new AFM cured it but dont forget to reset adaptations if you can

Re: Vauxhall Corsa 1000cc 2002

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 24, 2008, 10:28 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Peter Mutlow

Hi All.

Thanks for early responses. I get my Air flow meters from Vauxhall Spares centre. Genuine new Bosch units for £78 including P & P.

Regards

Pete M

Re: Vauxhall Corsa 1000cc 2002

Posted by Shaun Dale <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2719' width='330' height='300' border=0 style='border:none;'> on October 26, 2008, 10:58 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"

Repaired a three cylinder Corsa last week.
High CO, high lambda. On a hunch I blocked the tailpipe, found it blowing at the joint to the back box. Fixed that and then just got high CO, very careful listening at the front sounded like a small blow on the manifold when the throttle was snapped open. Took off exhaust pipe and found the seam had a hairline crack at the input to the cat, which a line of weld fixed. CO after repairing the exhaust was 0.04%, lambda 0.997. Thing is it really didn't sound like it a had a blow when it came in.
HTH Shaun

Re: Vauxhall Corsa 1000cc 2002

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on December 17, 2008, 6:50 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Peter Mutlow

Hi all,

This one has come back to bite my bum. New Bosch MAF fitted on 8 Dec and you guessed it, EML is back on. Made arrangements to revisit tomorrow about mid-day. Mark mentioned about re-setting the adaptations if I could. Well ACR G2 does not have that function so I didn't so I guess that could be the problem. If that is the case is it a main dealer job or can I disconnect the battery to do it assuming no radio code and immobiliser issues? If there is an ECU fuse then that could do the job. Will look on AD later. I know some adaptations can be undertaken by driving the car for about 20 mins and let ECU re-learn but may not be applicable on this car. Also when I fitted MAF another 2 fault codes popped up after re-starting car. They were PO300 and PO303 refering to a misfire. These have never appeared before and cleared down immediately. Customer has never had running problems so I assumed they were spurious codes - could be wrong. Grateful for early advice/comments. Will post findings tomorrow.

Regards

Pete M

Re: Vauxhall Corsa 1000cc 2002

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on December 17, 2008, 7:27 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"

Hi Pete

I had a similar fault on a Corsa apart from mine was a "too rich" fault code.

An adaption reset fixed mine. hth
Take a look at Nigel Yardleys post dated march 12th 2007. Ive tried to link to it see below hope it works.

Regards

Glyn

corsa

Re: Vauxhall Corsa 1000cc 2002

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on December 17, 2008, 9:08 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Peter Mutlow

Thanks for that Glyn. Looks as though I am back to adaptions issue still.

Regards

Pete M

Re: Vauxhall Corsa 1000cc 2002

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on December 18, 2008, 8:52 am, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Glyn Morgan

Hi Pete

I know the feeling, I remember spending too long on a Corsa before considering an adaption reset.

Have you anyone near you with Tech 2, Vaux Com, Snap on, who could help you out ?

Glyn

Vauxhall Corsa 1200cc 2002

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on December 18, 2008, 7:29 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Peter Mutlow

Hi All.

First mistake...vehicle is a 4 not a 3 pot. Anyway same fault code extracted PO 0170 (Fuel trim) and stft at 25% and ltft at -0.8% with no running faults. Did not start car because I wanted to remove pre-cat ho2 sensor and clean (very sooty). Started car and during warm up noticed pre-cat HO2 sensor not switching but stuck at 0.035v with stft remaining at 25%. Post Cat sensor reading normally at 0.46v. Engine sounded too lean which I expected with those readings. No air leak was found. Eventually (engine hot) HO2 sensor burst into life and STFT dropped to -2% and high 02 content dropped from 3.8% to 0%. CO2 rose from 13.8% to 16.8% (from memory). CO and HC remained at 0 during this process. As far as adaptations are concerned, have been advised today that this is not required for a car of this vintage, so we have conflicting opinions on that subject. Anyway, would welcome opinions from people who know better than me. Unless I hear to the contrary, will be changing O2 sensor next when I get the call.

Regards

Pete M

Re: Vauxhall Corsa 1200cc 2002

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on December 18, 2008, 7:57 pm, in reply to "Vauxhall Corsa 1200cc 2002"
Mark Carter

Hi Pete what part of the country are you in?

Regards Mark.
P.S hello Glyn.

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Corsa 1200cc 2002

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on December 18, 2008, 8:50 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002"
Peter Mutlow

Hi Mark,

North Lincs.......Car in Hull

Regards

Pete M

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Pete Mutlow on January 29, 2009, 7:02 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002"
Message modified by board administrator January 30, 2009, 1:04 pm

Hi all,

Its back again! Light came on again about 2 weeks ago and saw it again today. Same fault code and car runs perfectly. Have already changed MAF (Bosch) but still have conflicting opinions about adaptations. My gear does not have that facility unfortunately. All readings were perfect including STFT and LTFT. Now heres the thing. Used my ACR G2 to clear code whilst engine was running and it suddenly ran lean. Apart from hearing it go lean, HO2 sensor suddenly stuck at 0.1v and stft 25. Did not have 4 gas attached at the time unfortunately. So next bet is HO2 sensor which is going to cost about £85 from main dealer which the old boy can ill afford. If I can get positive info about adaptations, then I will send him to main dealers to have it done.

Many thanks

Pete M

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by John Cooke <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5461' width='330' height='300' border=0 style='border:none;'> on January 29, 2009, 10:07 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
John Cooke

Hi Pete
I have tech2
Garage in Hull
Will help if i can

JOHN

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 30, 2009, 7:20 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
Peter Mutlow

Thanks for your kind offer John. Will be in touch when light comes back on.

Regards

Pete M

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Tony Sefton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5581' width='330' height='300' border=0 style='border:none;'> on January 30, 2009, 7:35 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
Tony Sefton

I know that you said it was a Bosch AFM, But Was it a Genuine Bosch or GM part that fitted, ?? I would still be suspecting a faulty AFM if it hasn't got an air leak / fuel pressure problem etc.

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Darren Jones <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5495' width='330' height='300' border=0 style='border:none;'> on January 30, 2009, 9:24 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
Darren Jones

Hi Pete, on the 3 cylinder 1.0 corsa's when you clear the fault codes you also reset adaptions, i suspect yours does the same as when you cleared fault codes the engine management went back to basic settings & thats why O2 sensor suddenly read lean, if you looked at stft & ltft they would also of change to suggest the ECU was having to add fuel. I also think this car is running lean & also suspect airflow meter as i have had changed quite a few for running lean. Hope this helps Darren

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 31, 2009, 7:44 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
Peter Mutlow

Thanks Tony and Darren,

I will be very annoyed if I find that the "genuine" Bosch MAF I fitted is not what I was promised. For a few squid extra, I now find that I could have gone to main dealers and know that I have the genuine article. The relevation that the cancellation of the fault code could have automatically reset the settings is interesting. The moment I pressed the cancel button, the engine note changed and I got the lean readings. The engine was hot at the time and assuming the MAF was genuine then I have to seriously consider the 02 sensor. There was no switching of sensor at fast idle and no air leaks found. Will query MAF suppliers before I spend any more of the old boys money.

Regards

Pete M

Re: Vauxhall Corsa 1200cc 2002 PO 170 - UPDATE

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on April 16, 2009, 7:51 pm, in reply to "Re: Vauxhall Corsa 1000cc 2002"
Peter Mutlow

Evening all,

Thought I would do an update on this and give brief summary of history to save you trawling through previous posts. Low mileage car driven sedately by high mileage old boy. PO170 keeps popping up (Fuel Trim). Car drives perfectly and no issues with emissions. MAF changed with genuine Bosch unit. Lambda sensor (pre-cat) changed with NTK unit. Both items pico-scoped and working well. John Cooke kindly did smoke test, installed latest software and reset adaptations. PO170 popped up again on the very first drive. The clue to all this is that when I reset the EML with the engine running, the car can be heard and be seen to go lean with 02 at about 5% and both Lambda sensors stuck at about 0.2%. This will be the case for about 5mins or so and then gradually return to normal. So, on my last visit a couple of days ago I concentrated on this aspect. I went for the EGR valve thinking it may be partially stuck open allowing un-metered air into the intake although I thought this would cause crappy running. To my surprise, it did not appear to have an electrical solenoid although the EGR body and pipe leading off to the inlet manifold was there. ACT2 could not activate the operation of the EGR valve. Could anyone advise on this set-up. So, I left the EGR valve alone and did a "Heath Robinson" and blocked off the vacuum pipe on the crankcase-breather from rocker cover to intake. Cleared code down and mixture momentarily went lean and stabilised as normal. 02 at 0% and CO and HC at 0. Sold him some injection cleaner in case there is an issue with the injectors. So, now awaiting the call if it comes which will be in the next 2 -3 weeks
when the EML comes back on!

Regards

Pete M

Re: Vauxhall Corsa 1200cc 2002 PO 170 - UPDATE

Posted by Tony Sefton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5581' width='330' height='300' border=0 style='border:none;'> on April 18, 2009, 8:44 am, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170 - UPDATE"
Tony Sefton

Hi Pete. I am not 100% sure but on some Vauxhalls I think the EGR valve will only Actuate with the engine Running and can be seen to be working by watching the airflow signal. ??

( Air flow signal shows on the EGR Actuator screen )

I think it might be on these corsa's as i cannot remember actuating them in the normal method and hearing them click.

H.T.H. Tony.

Re: Vauxhall Corsa 1200cc 2002 PO 170 - UPDATE

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on April 20, 2009, 7:18 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170 - UPDATE"
Peter Mutlow

Evening all,

Its back!!! Precisely one day after my last visit customer takes vehicle for a spin and the dreaded EML is back on. I really have no where else to go on this unless someone out there can provide some inspiration. Tony: I have found out from main dealers that this vehicle does not have an EGR valve. Thanks for your input anyway.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Derek Sumnall <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5381' width='330' height='300' border=0 style='border:none;'> on April 21, 2009, 10:57 am, in reply to "Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Derek Sumnall

Hi Pete

Fuel trim codes are probably one of the worst to diagnose as they have so many contributory factors.
Last November I had a Kia Sportage code P0171 but with no running problems including hard accel up a steep bank,ruling out the MAF.
I did most of the normal checks having noted that the STFT & LTFT were +25.I cleared the code. Having the use of a CRecorder I was able to recognize on the grathing section downloaded to computer that the fuel trims were normal at cruise +-5% but climbed at idle.
This ruled out fuel pressure/injectors etc.
I had spent some time trying to locate what I believed to be a vacuum leak.
I tried again more thoroughly using a propane canister and long tube around the inlet manifold PCV & all vacuum take offs whilst connected to my gas analyser. Then I found it a vac take-off at the rear of the manifold out of sight had lost its cap. There had been no suction noise and the vehicle had no problem recently on MOT emissions.

Hope this helps
Dek

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on April 21, 2009, 5:39 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Hi Derek,

Many thanks for that. I am convinced this vehicle is running lean and will look carefully (again) for an air leak when I next re-visit. I am now thinking also that there could be an ECU issue with this and intend to speak to Vauxhall Technical help-line before I see my happy customer again.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on September 15, 2009, 7:50 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Evening all,

This thing is still not fixed. Spoke to Vauxhall and they thought it was a fuel quality problem so customer changed his supplier and put some Fuel System cleaner through it. This did not work and I managed to get hold of second hand MAF and HO2 sensor (Genuine Vauxhall parts from another Corsa) and the EML re-appeared after about a week. I have been back and forth to this vehicle for nearly a year and will make my final visit in a few days for another look and then admit defeat and let Main Dealers have a go. Any final thoughts would be welcome.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on September 15, 2009, 9:28 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Lee Mackintosh

not sure what you mean about the egr valve part, is it fitted but not working/wired up or has it had something modified we don't know about.

I know on the Z12XE that a 02 model is on the change over year if they have egr valves or not as i've fitted a later engine to a Y reg Corsa and that hadn't got an egr valve so needed to change ecu.

Am i correct in thinking that a P0170 fuelling error but not actually meaning its lean or rich, my point being are we looking for a lean condition but its not.

Have you ever posted up the emission readings and any live data such as fuel trim readings and eobd freeze frame data as this may help us/you.

Alot of replies to read through,

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Darren Cotton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1876' width='330' height='300' border=0 style='border:none;'> on September 15, 2009, 9:59 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Darren Cotton

Pete, I have read all of the post this with interest. Sounds like your having a nightmare.

What I would be doing is looking EOBD, see what codes you have there and look at the freeze frame data. (Can you post this info) This gives you a bit of info on what was happening at time of fault. The light is probably coming on after a week or two because of the drive cycles. Have asked him what conditions the fault appears. What Scan tool are you using? And have you done a smoke test on inlet manifold

Regards Darren

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on September 15, 2009, 10:30 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Hi Lee and Darren,

The EGR valve is not fitted. In its place is just the casting - ie no electrical connections. The scan tool is ACR4 g2. The old boy only drives it a few miles at a time in city traffic and the EML will illuminate at any point. The vehicle has been smoke tested courtesy of John Cooke and the latest software added via Tech 2. When I visit the vehicle the emissions are as perfect as you can get but when the EML is extinguished the vehicle immediately sounds lean and O2 rises to about 4.5%. This stabilises to normal after about 10 mins or so. The PO170 is obviously EOBD but when I run the Vauxhall protocol, PO170 is presented as an unknown code. On the odd occaison I might get the fault code relating to misfire (PO300 I think) but no report of misfiring by the owner. I have assumed this to be spurious but will have a closer look.

Will post freeze frame details on my next visit. Thanks for your interest.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Mark Mcgrath <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2806' width='330' height='300' border=0 style='border:none;'> on September 15, 2009, 11:16 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Mark McGrath

This is vauxhall tis definition of your code may be no help but ?

P0170 FUEL TRIM MALFUNCTION (BANK1)

Check the following component for proper operation:

Check intake system for leaking
Fuel pressure
Check function of the tank ventilation.
Check vacuum hoses for splits, kinks, leaks and proper connections.
Perform visual check of all exhaust related components for completeness, leakage and damage.

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Lee Mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on September 16, 2009, 8:10 am, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Lee Mackintosh

Look at the LTFT readings and see if they are a + or - figure so we can see if its requesting more or less fuel.

Could the P0170 fault code be a result of the P0300 as well, many times i've been corrected by others on here saying a misfire will cause excess oxygen which will then (i assume) be detected by the 02 sensor and alter fuelling to suit.

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Darren Cotton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1876' width='330' height='300' border=0 style='border:none;'> on September 16, 2009, 8:27 am, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Darren Cotton

I think that P0170 is the effect of your fault, if you have a misfire, then allot of oxygen will be measured down the exhaust pipe, this is why frame data and fuel trims should be looked at to see if it was try to add fuel or reduce it. Also ever time you erase the fault code, trims will revert to 0. so make sure you get all the info before erasing. You might find your self having to drive this through its drive cycles and recording data. Don't think sending it to dealer they will find it quickly if at all, this kind of fault is going to take a little time.

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on September 16, 2009, 11:45 am, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Thank you all for your responses. LTFT is always +25 which i believe means the ECU is trying to compensate for a lean mixture. I understand the link between high O2 and a misfire, however when the EML is cleared the vehicle runs lean but with no misfire present. However, I will be keeping an open mind on my next visit (when I'm in the area) and post freeze frame data etc.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on September 18, 2009, 10:11 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Mark Carter

Hi Pete, it seams that you have carried out all the basic tests, but just to confirm, what is the fuel pressure? What are the fuel flow readings? what is the MAP readings at idle and at part throttle?
whaen you re-set the trims what are the instant readings of air flow , injector duration, etc and how do they alter as the vehicle settles?

Regards Mark.

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on September 18, 2009, 11:00 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Thanks Mark. Will provide this info after attending the vehicle. Not done a fuel pressure check yet and unable to check fuel flow. I now have a long list of things to post which will be done on my next visit.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 2, 2009, 5:12 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"

Afternoon all,

Went back to vehicle today and here are my findings as requested:

Fault Code PO170 stored

Freeze Frame: Load 2%, ECT 92 degrees C
5 km/h, STFT 13.5%,
LTFT 0.8%, 800 rpm.

Emissions on arrival: 0% CO, 0ppm HC, CO2
16.1%, 02 0.3%

Fuel Trim on arrival: STFT 21.1%, LTFT 2.3%

Emissions after EML cancelled: o% CO, 20ppm
HC, CO2 12%, 02 5.8%
(These figures returned to normal after about 15 mins)

Fuel trim after EML cancelled: STFT 25%,
LTFT, -0.8%. (STFT dropped to 21% after 15
mins.)

Lambda sensor on arrival was switching
normally according to scanner (ACR4 G2) and
verified on probe. Scanner however
indicated a lean mixture even when blipping
the throttle. After cancellation of EML,
sensor stuck at about 0.2 and normalised
15 mins later.

MAF showing 1.4v and 1.2 g/s at idle and
approx 1.8v and 4.0 g/s at part idle.
These figures were more or less the same
before/after EML cancelled.

Unable to conduct fuel pressure check (no
schrader valve). Unable to conduct
injector duration check. (Forgot to pick
up my meter but will return if necessary).
Having driven the car, I do not feel there
is a problem with fuel pressure.

So there you are. The vehicle has been smoke tested, tech 2'd, Tank ventilation checked (removed fuel cap when testing), Vac hoses intact
and cannot see any exhaust leaks on down pipe.

If there is any other info you require, then I will be happy to make my 10th visit to this little beast!

Regards

Pete M

PS. Nearly forgot. This vehicle has already had two MAF sensors and 2 pre-cat Lambda Sensors fitted. The sensors now fitted are genuine Vauxhall items

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on October 2, 2009, 8:19 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"

Hi, the way I read your gas readings(before the re-set and directly after) you can not afford to ignore fuel pressure and flow checks.
If both are within spec, then the injectors need to be flow checked(glase build up)

In the following section I have simplified the ECU fueling process(its not perfect but near enough)

The ECU receives the mass air reading(sensor output voltage) and depending on load and engine temp, it uses a look up table(software loaded in the ECU)to fire the injector for a set time to attain an AFR (Air Fuel Ratio) of 14.7/1

The amount of fuel that will be injected for a set injector duration will depend on the pressure sitting behind the injector, the ECU can not measure the pressure in this system so it has to take it as read.

If the pressure was to high then more fuel would be injected for the same duration and vise-visa a lower fuel pressure would result in less fuel being injected

When the ECU reads the information from the AMM it applies a injector duration to suit the air mass entering the engine (lets call this the "mean" fueling).

Now, there is always a band(fuel trim) either side of this "mean" duration which is used for fine tuning the fueling(subject to the feedback from the O2 sensor).

If the fueling of the engine stays within the scope of the "look up tables" then the ECU is happy and the MIL stays off.

Only when the sums do not add up(as far as the ECU is concerned)does the MIL light up and a fault code logged.This happens when the limits of the adaptations(band width)are reached and the AFR is still not right.

If a fault code is logged saying upper limit reached, then the ECU is reading a weak mixture and is trying to richen it.

If a fault code is logged for lower limit reached then the opposite is true and the ECU is reducing the fueling to try to weaken the mixture.

Now you have to think of all the things that may cause the system to read either a rich or weak mixture.

As an example:
If the AMM is registering less air than the engine is using then the ECU will start off reading the output voltage of the AMM and doing its maths, then it will receive feedback from the O2 sensor saying that the mixture is weak, it will respond to this by adjusting the "fuel trim" in the positive way (more fuel).

It(the ECU) would carry on doing this until the feedback from the O2 sensor was good or until it reached its limits(MIL on).

Example no two:
If you had a small hole in the exhaust pipe up stream of the O2 sensor then this is likely to draw in air, which could cause the O2 senor to read a weak mixture(this would be false), the ECU would respond to this by increasing the fueling until the O2 sensor reported back that everything was good or until it(the ECU) again reached its limits.(in this case the true mixture would be very rich)

These are just two of many things that can and do effect fuel trims.
If we now think about what effect low fuel pressure could have on this system, we will see that guessing and assuming things will not cut the mustard. HTH

Regards Mark.

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Darren Cotton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1876' width='330' height='300' border=0 style='border:none;'> on October 2, 2009, 8:45 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Darren Cotton

Pete, I Have a Corsa same engine, 2001. I could record the live data and post it so you have something to compare with.

Do you have a scope?

Regards Darren

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on October 3, 2009, 2:34 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"

Hi Pete

Pleased to see you are not giving up on this one.

You post

Emissions after EML cancelled: o% CO, 20ppm
HC, CO2 12%, 02 5.8%
(These figures returned to normal after about 15 mins)

How I see it is after 15 mins the ECU has adapted the fueling to compensate for the lean mixture, ie 5.8% O2.( are these idle or cruise figures? )

The O2 sensor is reporting a lean mixture, confirmed by your emission figures.

Sorry for asking if you have posted it before, have you a manifold vacuum figure ?

Regards Glyn

PS Hi Mark, a pretty good explaination if you ask me

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on October 3, 2009, 3:48 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Lee Mackintosh

I'm not sure on this but isn't the STFT very high and causing the EML to come on.

I thought the maximum was around 15-20% +/- and the LTFT was about +/- 20% for EML to come on after a set amount of time.

I thought STFT were rapid adjustments to fuelling requirements so its (how i understand it) always requesting more fuel which is either low fuel pressure or flow or an air leak which has been checked and re-checked.

I'm sure i've read before that these cars suffer with in tank fuel pick-up problems as they sit in a swirl pot which is filled up under pressure from the return line of the fuel filter now if its got a weak return regulator could it cause the fuel to return to early which can result in low fuel flow and pressure.

Also would a low fuel tank content and poor pump/pick-up make matters worse.

How do you measure fuel flow, is it with engine running?

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Kevin Apps <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on October 3, 2009, 4:19 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Kevin Apps

Pete
I would like to know (exactly) how you tested the inlet manifold for leaks, as i have known the rocker cover to leak air into the manifold.
Kev.

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on October 3, 2009, 8:15 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Mark Carter

Hi Kevin, yes, so have I come across this before, which could cause the AMM to read a lower value than consumed and therefore start the whole STFT adaptation process.

Hi Glyn,I read the figures the same way, immediately after the re-set the O2 reading are too high, which if scoped at the same time the O2 sensor output would read a low voltage(if its a zinconia sensor)

And the ECU starts the ball rolling to correct the "error" by upping the fueling until it(the ECU) reaches its upper limit.

And on comes the MIL.

I think we all agree why the ECU is putting the MIL on, we now have to think of all the things that may cause the symptoms that we have.

Things like fuel pressure/flow, and air leaks come to mind straight away, as well as other numerous things such as, AMM outputs and manifold Kpa readings/valve timing etc.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 5, 2009, 12:26 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"

Hi all,

Thanks to all for your responses which I have studied in detail:

Mark. Thanks for putting the meat on the bones re: fuel trim. Found it informative which I am sure will be of help to others.

Darren. Thanks for your offer. I do not wish to trouble you with this at the moment but may take up the offer later if you still have the vehicle. Yes I do have a Pico.

Glyn. Thanks for your encouragement. Will get the before and after vacuum figures on my next visit. Emission figures are at idle.

Lee. I have noted (belately) that AD suggests there is a schrader valve on this but looks different to what I have seen on early models. Will post fuel pressure figures if I can get into it.

Kev. This vehicle has been tested with a smoke machine into the throttle body. No leaks were found. Take your point about the rocker cover which I will check on my next visit although I would have thought the smoke test would have shown something.

On my next visit

will check all the above points if I can. One good thing I have noticed is that I can conduct various tests with the vehicle permanately running lean by pressing the clear codes function on ACR4 every few minutes to reset ECU. Also customer appears happy to have mil on permanately because the car runs perfectly.

Regards

Pete M

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Dave Harney <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2603' width='330' height='300' border=0 style='border:none;'> on October 5, 2009, 2:08 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Dave Harney

Hi Pete,
Would you like to borrow a Crecorder to run around in the car for a week or so ?

Regards
Dave

You can trim a sheeps wool many times, but you can only fleece it once !

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Lee Mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on October 5, 2009, 7:37 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Lee Mackintosh

I have 2 corsa engines in my workshop but there a Z12XE and Z12XEP and only the Z12EXP has a fuel pressure test port which is on a later engine.

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 5, 2009, 9:01 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"

Evening all,

Dave. Thanks for your kind offer. Will have a think about it and will get back to you if necessary. However I must confess that I am beginning to tire of this vehicle after going back and forth for a year. I have made arrangements to have it smoke tested, tech 2'd and put numerous parts on it. Customer has decided to live with it and is happy at that. However, I am not. Don't like being beaten and will leave it for a while before going back to it.

Lee. Thanks for the info. Looks like that avenue is blocked but will have a look anyway.

Maybe the dealer is right - wants a new ECU in their opinion after discussing it with them.

Regards

Pete M

NB. Sure I have tested emissions at fast idle when running lean but cannot remember the results. Will check - next time

Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on October 5, 2009, 11:00 pm, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Lee Mackintosh

I've got a 2nd hand ecu for this type of engine Z10XE which you can borrow if needed but its not reset but i do have the immobiliser code to reset it.

Actually thinking about it i have the ECU, BCM, key reader and transponder chip but no instrument cluster but you could reset yours and re-align to the ecu/bcm for testing.

Let me know and we can sort it between us.

Re: Vauxhall Corsa 1200cc 2002 PO 170

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 6, 2009, 11:55 am, in reply to "Re: Vauxhall Corsa 1.0 2002 - MIL on and code P0170, fuel trim #"
Peter Mutlow

Hi Lee,

Thanks for your offer. Unfortunately somewhere down the thread this vehicle got converted from a !.2 to a 1 litre. Now corrected the vehicle details.

Regards

Pete M

NOT FIXED

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 26, 2009, 3:28 pm, in reply to "Re: Vauxhall Corsa 1200cc 2002 PO 170"
Peter Mutlow

Hi All,

I went back to this thing yesterday and Freeze Frame was as follows:

PO170
10 KMPH
LTFT 1.6%
STFT 3.9%
91 degrees C
800rpm
load 2%
Everything was as before ie: running perfectly and emissions spot on at idle/fast idle.

Checked Fuel pressure @ 3.8 bar (unable to check flow)

No leaks around rocker cover.

Again vehicle went lean on cancelling the fault code both at normal and fast idle.

Did all the usual checks again for the nth time - nothing.

Going to leave it now and wait if something developes. Old boy is quite happy - now has black tape over EML!

If something does develope it will be posted but I and I'm sure you have had enough of this one now.

Mind you, if I'm at a loose end.......

Thanks for your interest

Pete M

Re: NOT FIXED

Posted by carl ford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1822' width='330' height='300' border=0 style='border:none;'> on November 26, 2009, 8:19 pm, in reply to "NOT FIXED"
Carl Ford

Hi pete

This one looks like a right pain I have one of these cars as a courtesy car so if there is any live data readings you want I don't mind posting but lookin at it not sure if it will help.

Re: NOT FIXED

Hi Carl,

Thanks for that but I want to leave it for now because I am sick to death of it. Must pop in and see you and have a chin wag over a cup of tea - or something frothy!

Best Regards

Pete M

Re: NOT FIXED

Posted by Sanjay Odedra on November 30, 2009, 4:08 pm, in reply to "NOT FIXED"
Message modified by board administrator December 1, 2009, 8:14 am

1St Smoke machine test.Look at lambda vales on 4 gas, is it lean? lightly add propane / carb cleaner, introduce air leaks, does lambda value change/ does 02 sensor report rich/lean when it should?. Does yor Physicall 02 sensor voltage match up with live data on scan tool, Remember ALL sensor outputs/imputs have wiring looms which the ecu cannot diagnose seperatly.

Re: NOT FIXED

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 30, 2009, 7:59 pm, in reply to "Re: NOT FIXED"
Peter Mutlow

Hi Sanjay,

I can confirm that over the past 12 months I have measured the actual lambda reading and compared with scanner reading. Also I have tested the switching in the manner you have suggested. All tests proved ok. Vehicle was smoke-tested about 7 months ago and nothing un-toward was found.

Thanks for your interest

Pete M

Re: NOT FIXED

Posted by Sanjay Odedra on December 1, 2009, 3:51 pm, in reply to "Re: NOT FIXED"
Message modified by board administrator December 2, 2009, 1:16 pm

Does this engine have any external breather pipes/valves?

Re: NOT FIXED

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on December 1, 2009, 6:04 pm, in reply to "Re: NOT FIXED"
Peter Mutlow

Hi Sanjay,

Certainly does. Blocked breather pipes off and fuel tank vent pipe - no difference. There is a metal pipe which runs from the side where the EGR valve used to be, around to the back under the exhaust manifold which I can't blank nor clamp. However a smoke test did not show anything there and easy start has shown nothing. Would love to hear a nice hiss from somewhere!

Regards

Pete M

Fixed #

Posted by Pete Mutlow on December 14, 2009, 8:16 pm, in reply to "Re: NOT FIXED"
Message modified by board administrator December 16, 2009, 11:20 am

Evening,

Old boy's relatives clubbed together and presented it to Main Dealers. They fitted a new ECU (at great expense) and light has remained off now for nearly 2 weeks. Normally it comes on within a day or so. So after over 1 year, it is now consigned to history

Thanks for your contributions and interest.

Regards

Pete M

Re: Vauxhall Corsa - PO170 - FIXED

Posted by carl ford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1822' width='330' height='300' border=0 style='border:none;'> on December 15, 2009, 7:01 am, in reply to "Vauxhall Corsa - PO170 - FIXED"
Carl Ford

Hi pete

Sounds good to me pop in for a cupa any time ur in the area bud

Carl

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