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Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Lee Pritchard on June 23, 2010, 10:23 am

Year of Manufacture *: 51
Engine Size and Code *: 1100 hfx
( Optional ) Scanner Used: modis
( Optional) Fault Codes: P0420, P0172, P0134

Hello all

I had this saxo in yesterday, customer complained of surging when driving along,road tested vehicle and it does surge sometimes.

Had a visual look under bonnet for anything obvious, vehicle has full service history low milage car.

Plugged in scan tool came up with the following fault codes -
P0420 ageing cat

P0172 Adaptations,system too rich

P0134 o2 upstream o2 sensor

I scoped the pre a post o2 sensor and the were a mirror image of each other, which means the cat is u/s.Fitted new one and that was ok.

I then went into obd to look at fuel trims and found short fuel trim at around +10,there is no air leaks, removed throttle body and cleaned housing, refitted all ok, stft down to +2.long term fuel trim still at +4.7.

I tried clearing fault code in eobd and manufacturers side and the long term fuel trim is stuck at +4.7? does any one know if this is correct?

Thanks for any advice

Re: Citroen saxo 1.1 hfx,surging,fuel trim issue?

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on June 23, 2010, 10:51 am, in reply to "Citroen saxo 1.1 hfx,surging,fuel trim issue?"
Peter Mutlow

Lee,

Does this thing still surge? Have the DTC's come back? Replacing the Cat will not solve this problem. You need to establish what tne emissions are which may point you in the right direction if this vehicle still has a problem.

Rgds

Pete M

Re: Citroen saxo 1.1 hfx,surging,fuel trim issue?

Posted by lee pritchard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1074' width='330' height='300' border=0 style='border:none;'> on June 23, 2010, 10:59 am, in reply to "Re: Citroen saxo 1.1 hfx,surging,fuel trim issue?"
Lee Pritchard

hi pete,
yes i know fitting a new cat wont solve the problem,i was explaining the story with car.i have given it a short road test and seems ok at the moment,will give it a proper run at the end of the day and check if the codes reappear.it was the long fuel term fuel trim that was confusing me,as i have heard of ecu problems with these.thanks

Re: Citroen saxo 1.1 hfx,surging,fuel trim issue?

Posted by Dave Harney <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2603' width='330' height='300' border=0 style='border:none;'> on June 23, 2010, 11:26 am, in reply to "Re: Citroen saxo 1.1 hfx,surging,fuel trim issue?"
Dave Harney

Hi Lee,
Have you replaced the pre cat 02 sensor ?

Regards
Dave

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

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Ian Swanwick <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1887' width='330' height='300' border=0 style='border:none;'> on June 23, 2010, 6:00 pm, in reply to "Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Ian Swanwick

hi as far as am aware fuel trim is good as long as it is between -10 to + 10 when both short and long trim are added together. hope this helps

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on June 23, 2010, 9:32 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Mark Carter

The answer may be in the name. HTH

Regards mark

Modern cars, Its all wizardry and witchcraft

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on June 27, 2010, 6:01 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"

Hi Mark

I think that your last post might be a little unfair. (only a little mind!

) I understand why you like to make folk work for the answer though.

I think the guy is asking if there is an acceptable amount of trim correction & does his trim value stand out as a problem?

Fuel trims are similar to Trims that a pilot might make on an aircraft to keep it steady in flight. If a 747 has a load of fatties sat at the rear, then the pilot will need to "trim down". If the Oinkers were sat at the front he would then "trim up". I am sure that even a perfectly laden 747 on a perfect flying day, there would be some degree of trim correction required.

What should we consider to be excessive? Will a 75K motor be correcting for natural wear & tare & would a 4% LTFT value be acceptable?

Good questions methinks!

Cheers

Dave

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by mark carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on June 28, 2010, 1:30 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"

Hi Dave, I like your trim example, anything that gets the message across is good.
I thought that Lee was expecting the long term trim to return to zero(after clearing F/C) and was confused because it did not do so, maybe I misunderstood his first post.

It was for that reason that I replied in the manner that I did.

I find that Fuel trims, long or short confuse people and thats before you bring multiplicative and additive trims to the party, or LTFT moving the STFT base line and so on.

Maybe we need some sort of information system/training forum?

Regards
Mark carter

Modern cars, Its all wizardry and witchcraft

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by lee pritchard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1074' width='330' height='300' border=0 style='border:none;'> on June 28, 2010, 11:59 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Lee Pritchard

Hi mark,dave,
thanks for the advice, yes I'm a bit confused with the fuel trim issue,reason I am is that a few weeks ago I did a `petrol engine management course with james dillon at tech topics` (very very good course,took a lot away from it,james really delivers his courses well)i just don't want to be looking for a problem that is not there.

We were going through fuel trims,and the car we had hooked up to the diagnostic kit showed a+5% ltft,and after inducing an air leak the fuel trims altered as you would expect.

After doing a few test/demo's,we cleared fault codes and both ltft a stft went to zero,which on saxo is constantly on +4.7% ltft,which is making me think there is something wrong with this car,and just so i can get my head round the fuel trim issue.

I'm doing another course in a few weeks with tech topics so i will ask james just to clarify a couple of things,hope I'm getting the message over what I'm trying to figure out.I still haven't had the chance to have another look at the car yet.

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Sean Mc Gettigan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5291' width='330' height='300' border=0 style='border:none;'> on June 29, 2010, 8:15 am, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Sean McGettigan

Hi Lee, some systems will reset fuel trims when you clear codes and some won,t (have to reset as a seperate item).
Depends on the system. Thats why its always a good idea to note fuel trims before clearing code etc.

Hth
Sean

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by lee pritchard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1074' width='330' height='300' border=0 style='border:none;'> on June 30, 2010, 2:39 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Lee Pritchard

Hi sean

Thanks for the info, much appreciated,will record fuel trims in future.

Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on June 30, 2010, 7:44 pm, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Mark Carter

Hi Lee, there should be a good thread on the subject of fuel trims in the archives which should help you work out what is going on.

If it raises more questions than it answers then please post and I will try to help. HTH

Regards mark

Modern cars, Its all wizardry and witchcraft

Good Fuel Trim Thread

Posted by Peter Warman <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=Peter+Warman' width='330' height='300' border=0 style='border:none;'> on July 1, 2010, 7:55 am, in reply to "Re: Citroen Saxo 1.1 HFX 2001 - Surging & fuel trim issue, codes P0420, P0172 & P0134 #"
Peter Warman - Administrator

http://members5.boardhost.com/ukautotalk4/msg/1253723593.html

Re: Good Fuel Trim Thread

Posted by lee pritchard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1074' width='330' height='300' border=0 style='border:none;'> on July 1, 2010, 10:28 pm, in reply to "Good Fuel Trim Thread"
Lee Pritchard

Thanks for all the info,a bit better knowledge now on fuel trims.

Re: Good Fuel Trim Thread

Posted by stephen wright <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1023' width='330' height='300' border=0 style='border:none;'> on October 12, 2012, 11:37 am, in reply to "Re: Good Fuel Trim Thread"
Stephen Wright

I know it a while ago you had this problem but did you fix it?

Re: Good Fuel Trim Thread

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 14, 2012, 5:18 pm, in reply to "Re: Good Fuel Trim Thread"
Mark Carter

Probably better to start a new thread.

Mark

Modern cars, Its all wizardry and witchcraft

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