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Jeep Patriot 2.4 2007 - Fault code P0171 system to lean - Fixed #

Posted by Keith Brown on February 17, 2011, 4:59 pm

Year of Manufacture *: 2007
Engine Size and Code *: 2400cc
( Optional ) Scanner Used: ss3

Inherited above car from another garage with this fault code, previous garage fitted new o2 sensor, 100miles later light back on
symtoms so far; car at running temp emmisions perfect o2 sensor switching nicely, after approx 60 seconds of every start up o2 sensor flat lines to 0v & injector duration increases to 6ms ,cant see exactly which occurs first!, co% through the roof, oxygen level good at .075%,cannot detect air leak on inlet side, all other parameters i can see using eobd seem fine,
sadly unable to access fuel pressure, also very limited for any other data
whilst car is running good STFT -10% LTFT 23%
after it drops out STFT & LTFT are both 32%
Bit stuck on this any help would be appreciated keith ps sorry about the long post

Re: jeep patriot P0171 system too lean

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on February 17, 2011, 5:45 pm, in reply to "jeep patriot P0171 system too lean"
Peter Mutlow

Hi Keith,

Making the assumption that the vehicle runs ok. How long does it take for the EML to come on? Any idea what make the 02 sensor is? Might be an idea to run checks on MAF/MAP sensor.

Regards

Pete M

Re: jeep patriot P0171 system too lean

Posted by keith brown <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1429' width='330' height='300' border=0 style='border:none;'> on February 17, 2011, 6:47 pm, in reply to "Re: jeep patriot P0171 system too lean"
Keith Brown

thanks for quick reply pete,eml comes on after approx 4 start cycles,vehcile is slightly hesitant on accel on occasions but i put that down to engine attempting to clear itself,possibly wrongly!
the o2 sensor has a bosch part number on? , this runs map only i will scope tomorrow,this is one of those cars that gets to you,has two annoying immobilizers fitted ,which always need resetting & a poxy clutch switch,just to add to the stress! also preety frustrating not to have any spec to compare with,going back to the map sensor,if faulty , would it flag an 'out of spec" or coherance fault code instead of just lean mix & why lean mix if its obviously rich
ps sensor 2 also flat lines during fault,could this simply be ecm failure, sorry looking for bullet!

Re: jeep patriot P0171 system too lean

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 17, 2011, 7:08 pm, in reply to "Re: jeep patriot P0171 system too lean"
Mark Carter

Hi Keith,

As far as I can tell from your post the ECU is responding correctly from the info that the Lambda sensor is suppling.

So two options come to mind, first, promote change in the sensor reading and see if the ECU responds to the incoming signal.This will confirm my thoughts.

Smoke test the exhaust system and look for any leaks upstream of the sensor.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: jeep patriot P0171 system too lean

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5535' width='330' height='300' border=0 style='border:none;'> on February 17, 2011, 7:17 pm, in reply to "Re: jeep patriot P0171 system too lean"
Alan Kane - Administrator

<<< o2 sensor flat lines to 0v >>>

Low O2 signal could be excess O2 in the exhaust or a faulty signal.

<<< why lean mix if its obviously rich >>>

The ECU is seeing a lean signal from the O2 sensor and so it commands more fuel to compensate.

<<< oxygen level good at .075% >>>

Are you sure there is not excess O2 showing on the gas analyser when the sensor signal is low?

You need to either find where the excess oxygen is coming from or check/repair the sensor signal.

Re: jeep patriot P0171 system too lean

Posted by Mark Carter on February 17, 2011, 9:36 pm, in reply to "Re: jeep patriot P0171 system too lean"
Message modified by board administrator February 22, 2011, 2:32 pm

Hi Alan,
>>>You need to either find where the excess oxygen is coming from or check/repair the sensor signal.<<<

Does that post not copy mine ?

Regards Mark.

Re: jeep patriot P0171 system too lean

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5535' width='330' height='300' border=0 style='border:none;'> on February 17, 2011, 11:14 pm, in reply to "Re: jeep patriot P0171 system too lean"
Alan Kane - Administrator

<<< Does that post not copy mine ? >>>

I am not sure that deserves an honest answer mark, or any answer, but regardless of that, no, and I think you have a cheek to suggest same….

Re: jeep patriot P0171 system too lean

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 February 18, 2011, 7:50 am, in reply to "Re: jeep patriot P0171 system too lean"

Yes it does Mark, I'd presumed Alan was replying before seeing you post (approx same time) but maybe not.

Sean

Re: jeep patriot P0171 system too lean

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 9:25 am, in reply to "Re: jeep patriot P0171 system too lean"
Mark Carter

Hi Alan,

Again, Sorry if I have hurt your feelings (looks like I hit a nerve) But I can't see the point of posting the same help twice.

Maybe its just me but it is getting harder and harder to post on this site without upsetting someone.

Perhaps its time to stop trying.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: jeep patriot P0171 system too lean

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 11:04 am, in reply to "Re: jeep patriot P0171 system too lean"
Peter Mutlow

Mark,

No!

Rgds

Pete M

Re: jeep patriot P0171 system too lean

Posted by keith brown <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1429' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 11:09 am, in reply to "Re: jeep patriot P0171 system too lean"
Keith Brown

all ive got to say is "great minds think alike"
now back to my problem,i still dont think its excess air in system ,my resoning for this is the vehcile runs perfect for about 1min & then it crashes! the upstream sensor is happily adjusting at regular intervals,[sorry cant post scope graph] & then drops to 0v at the same time sensor 2 also drops to 0v,surely rear sensor should now see NO oxygen & attemp to alert the ECM that theres too much fuel in system,by this time emmisions off the scale,your views

Re: jeep patriot P0171 system too lean

Posted by Bryan Smith <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5330' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 11:30 am, in reply to "jeep patriot P0171 system too lean"
Bryan Smith

I would have thought a faulty MAP would have the same effect as a faulty MAF? Forgive me if I'm wrong but I don't think the MAP has been confirmed as correct, apart from "all other parameters i can see using eobd seem fine". Fuel pressure is another thing that I would have thought was a possibility that has yet to be checked?
Regards, Bryan.

Re: jeep patriot P0171 system too lean

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5535' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 11:39 am, in reply to "Re: jeep patriot P0171 system too lean"
Alan Kane - Administrator

Mark,

This has nothing to do with “hurt feelings”, “hitting a nerve” or me being oversensitive. You typed that I had copied your post. That in my book is unacceptable and insulting.

You now say “I can't see the point of posting the same help twice”. I would respectfully suggest that if that was what you meant then that is what you should have typed.

I really can’t be bothered to defend my posting something which was after all very basic.

That’s my final word on the subject.

Keith, apologies for corrupting your thread.

Re: jeep patriot P0171 system too lean

Posted by Steve Harrison <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1363' width='330' height='300' border=0 style='border:none;'> on February 18, 2011, 2:49 pm, in reply to "Re: jeep patriot P0171 system too lean"

Keith

Do you have a sensor simulator? If you do try simulating the lambda switching from just after engine start-up and see if this makes a difference.
Some years ago I had a Wrangler 4.0 with similar lanmbda sensor / injector duration behavior to yours i.e. dropping to 0 volts during the initial 60-90 seconds of running. Also it was reluctant to go into closed loop.
This had a universal sensor fitted by another garage and I found that if a good signal was simulated all the issues disappeared. Fitted a genuine sensor and it started to switch within approx 20 seconds of starting and went into closed loop shortly after. HTH

Steve

Re: jeep patriot P0171 system too lean

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on February 19, 2011, 8:06 pm, in reply to "Re: jeep patriot P0171 system too lean"

Mark

I don't know Alan personally, but I think that you have made a bad call here.

I suspect that his post was written, without consideration of what you had written, maybe that was because the two posts overlapped or maybe he just hadn't read yours. I often post something, only to look back & see that my advise was a duplicate of someone else's further back in the thread. I certainly wouldn't be happy at being chastised for it.

Alan has never really stood out to me as having an ego that needs a massage.

Pete

I can't believe that you haven't asked for a fully detailed gas printout, this would be a deffo good case for one.

Keith

I would be looking at challenging all entry points to the intake fanimould, i.e. the servo & EVAP connections & confirming that you have no leakage.

Its a bugger when you can't test fuel pressure & flow easily, but it is worth pursuing that line, if more obvious tests don't reveal the answer.

I am sure that if you had gotten hold of this earlier on, then it wouldn't have had an oxygen sensor wasted on it. Most O2 sensor (Zirconia or Titania) can be prompted to switch, with a few vigorous pumps of the accelerator. The response observed will help you decide if they are fubar or not.

I haven't seen one of these motors yet, but autodata suggests that is uses a MAF sensor input for one of the primary fuel metering calculations. Can you confirm that it has a Mass Airflow Meter & maybe gain some tests data from it?

The trouble with rarely seem vehicles like this, is that useful "good data" can be hard to get hold of. It was a Vectra, then you would be quids in!

Re: Jeep Patriot 2.4 2007 - Fault code P0171 system to lean #

Posted by Michael Whitworth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5568' width='330' height='300' border=0 style='border:none;'> on February 19, 2011, 8:40 pm, in reply to "Jeep Patriot 2.4 2007 - Fault code P0171 system to lean #"
Mike Whitworth - Administrator

Hi keith,

I know Alan very well and respect his opinion, I don't know Mark but from what I read I also respect his opinion, However I think any opinions or comments in answer to a post as long as they are valid are OK even if someone else has already posted simmilar, at least then you can form a veiw based on this.

With regard to your subject matter, first and foremost I would be confirming the lambda sensors functionality. From your post and the information you provide it seems obvious to me that the lambda sensor is suddenly failing causing the system to react to a false lean condition. your fuel trim figures also support this.

What make was the new sensor? was it genuine? who fitted it? did they actually test the old one before replacing?

Chances are once you sort this out you will then have to tackle the original fault as like most garages there was probably nothing wrong with the original sensor and they have just made it worse "Cos thats what the scanner said it was".

Just my thoughts,

Mike

M.O.M. Miserable Old Manc

Re: jeep patriot P0171 system too lean

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 20, 2011, 10:29 am, in reply to "Re: jeep patriot P0171 system too lean"

Hi Alan, I have just re-read my earlier posts and;

If my post come across as "unacceptable and insulting". then I apologise, it was not meant to be in any way shape or form.

I was simply noting that it was offering similar advise based on system knowledge. The word "copy" was used in this way.

It is not my intention to deliberately insult anybody on this forum.

Keith,
Have you had time to carry out any tests, and if so what are the results?

Regards Mark

Modern cars, Its all wizardry and witchcraft

Fixed #

Posted by Keith Brown on March 2, 2011, 2:22 pm, in reply to "Jeep Patriot 2.4 2007 - Fault code P0171 system to lean #"
Message modified by board administrator March 4, 2011, 2:13 pm

Rear sensor shorting out after a few seconds shutting front sensor down,only found it by running car with rear disconnected,thanks for your input,hope u are all still freinds!!!

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