Hi Jag v8, and first thanks for ur time.diagnostics said p0174 and p0171 lean codes bank 1and 2.
As I said I I have checked all potential causes that normally can flag this error apart off egr valve!
Any better suggestions ?

 

Before spending more money. You can remove the EGR and block off the opening.

This will give you EGR errors but you expect that. Then clear all codes and see if the 171 and 174 come back after driving around.

If this is too much work and you have the money it won't hurt to replace the EGR valve just be aware that we don't have any proof that is your problem. It could be but we don't know yet.

It's not common and I have not seen it reported before but our cars are getting older and more things will fail with time.
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Chasing the P0171 P0174 myself now. 2004 XJR. Removed and inspected all air lines in engine compartment for leaks and none found. Restricted performance comes after heavy foot occasionally and than goes away for abit allowing spirited drive time again. Found Fuel pressure at 55PSI and as high as 63PSI with foot in it to 90MPH, I did notice the occasional drop below 55PSI (47) at times so its possible pump is getting weak, but I doubt it. Replaced fuel filter (90,000 miles)and nasty ink colored fluid spewed out. Added techtron fuel injector cleaner as a crutch and now waiting for full tank of said fluid to run its course. I recently replaced all coolant hoses so it is possible leak at Intake manifold has occurred when it was removed and going to hook up scanner for ST and LT bank readings just to verify if Vacuum leak is present. I also suspect and expect to find possible problem exists with upstream O2 only because they are original and downstreams failed 6 months ago requiring replacement...perhaps its time for those as well. MAF sensor is clean as a whistle so not as concerned with that. If my readings for vacuum leak are in spec than a trip to the dealer will be in order and I will report what was found.
This forum has been a great source of both knowledge and comedy so thank you.

 

Well no time yesterday to borrow the scanner, but reinspected MAF and found alittle blacker on one side and amber on the other. Decided to use electric cleaner spray to remove soot and clean terminals on connector as well as using dielectric grease for said connector. Drove this morning and thought all was well and RP popped up at 35-40 mph and very conservative driving circumstances...oh well. RP disappeared within 1 minutes time. Did I mention I hate chasing intermittent electrical issues(assuming electrical) as I cant image this being a vacuum leak anymore because of its inconsistent behavior. This problem seems to come at anytime than go away...still need to read bank vacuum as borrowing a scanner costs me nothing but time and beats throwing parts at it. UGH

 

Motofreak72,

Have you checked the charge on your battery? My car is in a service shop now as we speak due to the same codes. I ripped apart the intake manifold, fog tested all vacuum lines and nothing! I removed my MAF sensor, cleaned it and all electrical connections-still nothing. I've become a wiser man with age and conceded to a professional. The battery was at 40%. An overnight charge got to 80% (replacing battery) however after clearing the codes and doing a test drive, no codes returned! No bogging and short of acceleration during "punches". I highly recommend the battery check as it will save money AND TIME. Hope this helps an good luck.

 

Thank you for the input. I replaced Battery last year. Voltage right now at 12.8 and between 13-15 VDC running and above. I am pretty good about batteries as with this Florida heat and humidity it can take its toll. I also know the value of a good battery tender. Im off to my Indie to try a couple other ideas before taking the plunge and sitting at dealer all day. Im still thinking O2 or bad MAF as it appears to happen more when just off throttle and kicking down...we shall see. Thank you again.

 

OBD. Engine hot, parked. LTFTs at idle & 2500rpm will confirm whether an air leak.

 

First thanks for all ideas shared here.
I am in same situation chasing p0171 & p0174 engine runs lean bank 1 and 2. I have checked for leaks vacuums etc, smoke test maf all ok. Only presumend mechanical problem that I think of, can be the EGR. If any better suggestion please let us know. (Same probl as motofreak72 , EML and restrict perform comes and go)

 

Do LTFTs show air leak?

 

Well this is what I have. I took my measurements with engine hot and @ idle and roughly 2500RPM after clearing the engine fault light and restrictive performance light.

After code clear

Engine Hot idle/2500 rpm
STFT 1 2.3-3.1 / 16.4-17.2
STFT 2 0-4.7 / 10.9 -11.7

LTFT 1 19.5 / 1.6
LTFT2 14.1 / 1.6

MAF .63 idle/ 1.97


Now, I did take measurements before clearing codes and don't know or think they matter much with the light on but here is what I recorded

Before code clear:

Engine hot idle/2500rpm
STFT 1 - .8/ 5.5-7.3 Sorry These readings here are the only ones in the negatives at idle only
STFT 2 -7.0/ 3.9 Same here

LTFT 1 19.5/ 1.6
LTFT 2 14.8/ 1.6

MAF .62/ 1.84

So going back to the 2011 posts I guess its safe to assume I have a leak? I am not sure as to what or where to start. I thought even the MAF reading was low.

What's your input JagV8?

 

You have a vac leak on bank 2. Look at stft only, long term is a correction factor. And as you can see you did not clear long term fuel trim and these need to be cleared. Even if you fix a problem youll be dealing with ltft skewing the issue before they will reset and youll be a dog chasing your tail. Do a hard reboot and see if that clears them for you. And only really worry about idle stft when vacuum is highest and easy for you to deal with finding the issue. When monitoring spray areas of potential leak sources, ie gaskets, vacuum piping hoses etc. And look for a large negtive swing in the stft. When it does you found the, or one of the sources

 

Ok that's what my plan is than today...fight the demon. Only thing. Hard reset? Im alittle confused there. Thank you for sending me in the right direction both of you JagV8/Brutal

 

Disconnect battery, wait 10 secs, short connectors together, reconnect to battery. Will clear codes & trims & force relearn.

 

I dont know about the UK, but in the US OBD2, that DOES NOT reset check engine lights. But it should, iirc reset LTFT. I useally just clear adaptation with a scanner since Im already there for monitoring trims

 

Hi , on my STR there is no air leak for sure.maf is ok.
Fuel pump pressure is perfect.
My question is. if the egr really can give these codes, or what other cause can trigger this fault which comes Amy goes ...

 

JagV8- I will try that as it wont cost me anything but a few minutes of my life
Brutal- The scanner I used for the readings I did...well I thought I did clear the codes(erase). I guess if theres no harm in disconnect and shorting (positive and negative terms) while disconnected than right after I can check scanner and erase any codes and perform test again.

 

maybe im not being crystal, a scanner will clear codes but most will not clear ltft. I use a jaguar scanner to clear adaptaions and ltft. My comment refferred to doing a hard reset to clear ltft which i believe it will. But a hard reset will not clear codes on a obd2 market equiped car as eluded to by jagv8. It may do this in the uk, but not here. And just didnt want people reading thinking you can still do that(that was old school obd1) if you do a hard reset then look at ltft again with your scanner and they should be reset to 0

 

Thank you. Thats what my initial thought was but I was not 100% sure. I also remember hearing along time ago that our (us spec) cars don't reset by doing the battery trick...unfortunately. I really dont have the option I suppose than but to visit the dealer and pay there $120. to read and reset codes. oh well. I just want to find this leak right now and will let you know what I find because I hate when someone starts a thread and doesn't follow up with the end result. Again your knowledge is appreciated sir.

 

This is odd, we've had lots of (US included) people whose codes clear with battery disconnect. They come back if the fault still exists, of course. Many take 2 trips as per JTIS (and the US and other laws). Somebody try it, please!

 

I will try it. It doesnt hurt right. lol.... No really I will be the test subject if need be and let you know.