LS1 - P0171 and P0174 both banks running lean
12-12-2014 | 07:22 AM
#41
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From: Monroe,NY
12-13-2014 | 01:39 PM
#43
Codes P0171/174 Yes, used new gaskets. Everything remains the same with the codes and chirp once warmed up. The search continues. Again, is there any reason why I can't clear codes while driving?
12-13-2014 | 08:18 PM
#44
If it will let you, I don't see how it would harm anything. Never tried that specifically. I think the codes would either clear or they wouldn't and that would be about as exciting as it would get.
12-14-2014 | 03:11 AM
#45
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Update on my car:
I bought a vac gauge the other day and plugged it in this morning. It sat on around 18 nearly rock solid (maybe fluctuated 1/4 of a gradution at most) in neutral and around 19 when in drive. When I blipped the throttle it immediately dropped to less than 5 and then straight up to 25 before returning to around 20 and quickly settling to 18. I held rpm at around 3000rpm for a while and vac went to around 22 and stayed there till I returned to idle. From everything I have read the motor is at the lower end for normal limits. I'm upping some stuff to tube which I'll post shortly.
Last edited by RedHotMike; 12-14-2014 at 03:21 AM.
12-14-2014 | 03:33 AM
#46
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Youtube of the above. Just give it a few min to process and it'll be up 
https://www.youtube.com/watch?v=EkQq...ature=youtu.be
https://www.youtube.com/watch?v=EkQq...ature=youtu.be
12-15-2014 | 01:00 AM
#47
That kind of behavior for vacuum is normal I believe. With throttle closed at idle, engine is trying to suck more air and can't, therefore vacuum is high. Blip the throttle, you remove the restriction, vacuum is low temporarily. Hold it at 3K, vacuum builds because motor us spinning faster but throttle is only open a part of the way, still presenting restriction and building vacuum.
Or were you just trying to show normal?
Or were you just trying to show normal?
12-15-2014 | 01:37 AM
#48
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That kind of behavior for vacuum is normal I believe. With throttle closed at idle, engine is trying to suck more air and can't, therefore vacuum is high. Blip the throttle, you remove the restriction, vacuum is low temporarily. Hold it at 3K, vacuum builds because motor us spinning faster but throttle is only open a part of the way, still presenting restriction and building vacuum.
Or were you just trying to show normal?
Or were you just trying to show normal?
12-15-2014 | 08:47 AM
#49
Could your injectors be getting a little clogged or a little tired and not releasing enough fuel at very small pulse widths(like at idle)?
This thread has been hijacked a few times and I can't remember exactly what bits were yours vs. others..did we somehow rule out a bad IAC or are you DBW?
Could your MAF be put of calibration a bit?
Just throwing stuff at the wall at this point. I worry that there could be a small vacuum leak but with the PCM compensating to keep idle target you could still have vacuum but I don't know how else to check other than pull all the intake rockers(closing intake valves) close off throttle body, block all vacuum ports, and do some sort of intake leakdown(vacuum retention?) test.
This thread has been hijacked a few times and I can't remember exactly what bits were yours vs. others..did we somehow rule out a bad IAC or are you DBW?
Could your MAF be put of calibration a bit?
Just throwing stuff at the wall at this point. I worry that there could be a small vacuum leak but with the PCM compensating to keep idle target you could still have vacuum but I don't know how else to check other than pull all the intake rockers(closing intake valves) close off throttle body, block all vacuum ports, and do some sort of intake leakdown(vacuum retention?) test.
12-16-2014 | 02:28 AM
#50
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This thread has been hijacked a few times and I can't remember exactly what bits were yours vs. others..did we somehow rule out a bad IAC or are you DBW?
Could your MAF be put of calibration a bit?
Could your MAF be put of calibration a bit?
Just throwing stuff at the wall at this point. I worry that there could be a small vacuum leak but with the PCM compensating to keep idle target you could still have vacuum but I don't know how else to check other than pull all the intake rockers(closing intake valves) close off throttle body, block all vacuum ports, and do some sort of intake leakdown(vacuum retention?) test.
12-16-2014 | 08:54 AM
#51
Another long shot...could the injectors not be firing as well at low speeds for an electrical reason? Are the battery and alternator fresh? Have you checked all of your grounds?
12-16-2014 | 09:38 AM
#52
Have you pulled spark plugs yet? Fouled plugs commonly cause an idle issue that clears up a little with faster engine speeds, pressure and heat when combustion conditions are better. O2's read raw fuel as being lean.
12-16-2014 | 08:21 PM
#53
code P0171, P0174 Interesting thing happened today. I put a new steering pump in along with a new belt idler and early this morning went for a test ride. The temp was about 40 degrees when I set out. After traveling thru town and making several stops it dawned on me the SES light was not on. It finally came on during the return trip. Leads me to think that the fuel map provides more fuel in colder temps. Anyone got insight on this?
12-17-2014 | 05:21 AM
#54
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I put new plugs in when I did the valve springs and pulled one a few weeks back. All looks normal to me.
12-17-2014 | 05:22 AM
#55
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Interesting thing happened today. I put a new steering pump in along with a new belt idler and early this morning went for a test ride. The temp was about 40 degrees when I set out. After traveling thru town and making several stops it dawned on me the SES light was not on. It finally came on during the return trip. Leads me to think that the fuel map provides more fuel in colder temps. Anyone got insight on this?
12-17-2014 | 05:51 PM
#56
code P0171, P0174 Our symptoms are exactly alike. If we continue to exchange info we should be able to come up with an answer. In an earlier post I mentioned a chirping sound that didn't seem to be RPM related. Discovered what it was today. I had blocked off the small hole in the throttle body not knowing it was part of the PCV system. This kinda proves I don't have a vacuum leak. The codes are set during a coast down rather than steady or increasing RPM. Seems there is something going on with the air/fuel mixture during this event. Question is, is it getting to much air or not enough fuel?
12-17-2014 | 06:25 PM
#57
I know you guys said you cleaned your MAF but maybe try /one/ more time and also maybe put some dielectric grease in the connectors for that, MAP, O2 sensors? Even increased resistance due to slight corrosion or even just not good surface contact can cause strange readings..these are analog sensors right?
The reason I am back to this is a just got deja vu from my 5.0 days when a dirty or fussy MAF would cause idle surge and sometimes a O2 code when coasting at low or no throttle..something with the MAF not reporting the little bit of additional air that was being sorta forced into the intake from the fender of the car due to air moving past the car.
The reason I am back to this is a just got deja vu from my 5.0 days when a dirty or fussy MAF would cause idle surge and sometimes a O2 code when coasting at low or no throttle..something with the MAF not reporting the little bit of additional air that was being sorta forced into the intake from the fender of the car due to air moving past the car.
12-19-2014 | 01:35 AM
#58
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Ok - went to see a mate last night with HP Tuners. He has 1/2 a clue and I have nfi with such black magic but we did this:
interesting log.
couldn't log fuel pressure sadly, not sure why, but whatever. what we did see is MASSIVE swings in O2 voltages, ranging from 80mV to 800mV on both banks.
we were able to replicate the SVS light by taking off the RHS rover cover breather (to the intake before the TB) and blocking it off. crankcase would build pressure, release the pressure and bam, SVS light. now whether that's the same code as what its doing normally, or just triggering and SVS due to high vacuum in the crankcase, im not sure, the code seemed to self clear. we did managed to trigger the lean codes once though.
I noticed the LTFT went up to 18.8% just sitting at idle.
im still saying a vacuum leak but thought id post up to get some ideas. a visual inspection of the engine is fine.
couldn't log fuel pressure sadly, not sure why, but whatever. what we did see is MASSIVE swings in O2 voltages, ranging from 80mV to 800mV on both banks.
we were able to replicate the SVS light by taking off the RHS rover cover breather (to the intake before the TB) and blocking it off. crankcase would build pressure, release the pressure and bam, SVS light. now whether that's the same code as what its doing normally, or just triggering and SVS due to high vacuum in the crankcase, im not sure, the code seemed to self clear. we did managed to trigger the lean codes once though.
I noticed the LTFT went up to 18.8% just sitting at idle.
im still saying a vacuum leak but thought id post up to get some ideas. a visual inspection of the engine is fine.
12-19-2014 | 04:24 AM
#59
If you have a vacuum leak its not a big enough one to cause an issue, your map readings are showing what it should with the car at an idle. There is no way for crankcase pressure so set a light, I would like to know what code it is throwing when you release the crankcase pressure.
Those fuel trims are outrageous! I wish I could have this car in my shop, I love figuring stuff like this out.
Those fuel trims are outrageous! I wish I could have this car in my shop, I love figuring stuff like this out.
Last edited by Horsepwraddict; 12-19-2014 at 04:43 AM.
12-19-2014 | 04:29 AM
#60
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Your MAP readings are showing very low vacuum. With a stock motor you should be up around 65-70 kpa. 35kpa puts you at like 10 inHg.
Maybe im misunderstanding a little bit of what you said but it sounds like your getting tremendous amounts crankcase pressure? Maybe its acting as forced induction through your PCV system. lol Cheap Boost!
Or maybe you just have a bad MAP.
Maybe im misunderstanding a little bit of what you said but it sounds like your getting tremendous amounts crankcase pressure? Maybe its acting as forced induction through your PCV system. lol Cheap Boost!
Or maybe you just have a bad MAP.