P0171/P0174 Help!
in [Technical]
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From: Pete C. on 19 Jul 2008 20:40 mr158912 wrote: > > it seems to me you have a vacumm leak of some sort either intake > plenium/manifold gsaket or egr valve and maybe evan a pcv system leak > but looking at your posted data even without o2 data i must ask if you have > a cold air intake kit with a k&n filter the oil from them plays hell with > the maf sensors > i would expect to see a little more maf signal at 1400rpms > mike the days of your kind of repairs and troubleshooting are going away > fast Well, I sprayed some B12 around the IM while the engine was idling and didn't note any detectable RPM change. The intake is stock and there is a "normal" filter in place. I did try a K&N filter way back when before deciding it was of no value. That was a long time ago and the MAF has been cleaned with CRC MAF cleaner since then. Another freeze frame had RPM at 2521 and MAF at 7.152 lb/min. > "Pete C." wrote: > > > '97 Chev K3500 7.4L > > > > Been chasing after the source of intermittent P0171/P0174 (always both > > set) for some time without success. I'm running out of ideas on what to > > check now, I don't have a full feature scan tool so I can't perform all > > the possible checks. Some of the possible items seem to not be > > applicable due to it always setting both codes, i.e. exhaust or HO2S > > issues not likely since it's dual exhaust with dual cats. > > > > I've replaced the fuel pump recently and the tank interior was spotless, > > so clogging / contamination is not likely. I just replaced the FPR and > > it's filter screen was clean as well. The FPR did fix pressure leak down > > on pump shutoff, but that seems to not have been a significant issue. > > > > I did plugs/wires/cap/rotor while I was at it this last service > > Saturday, and the removed plugs all had moderate tan deposits that seem > > consistent with the 130k or so on them. I also cleaned the IM passages > > and ports while things were apart. > > > > I do have freeze frame data from the trouble codes as noted below: > > > > Closed loop / closed loop > > Calc. load 19.2% > > Coolant temp 167F > > ST1 0.7% > > LT1 24.9% > > ST2 1.5% > > LT2 24.9% > > MAP 17.4 in/hg > > RPM 2521 > > MPH 65 > > MAF 7.152 lb/min > > TPS 20.7% > > > > No trouble codes other than the P0171/P0174 have ever been set. > > > > Any ideas where else to look? > > > > Thanks!
From: W. Stief on 19 Jul 2008 22:46 Pete C. wrote: > mr158912 wrote: >> >> it seems to me you have a vacumm leak of some sort either intake >> plenium/manifold gsaket or egr valve and maybe evan a pcv system >> leak >> but looking at your posted data even without o2 data i must ask if >> you have a cold air intake kit with a k&n filter the oil from them >> plays hell with the maf sensors >> i would expect to see a little more maf signal at 1400rpms >> mike the days of your kind of repairs and troubleshooting are going >> away fast > > Well, I sprayed some B12 around the IM while the engine was idling and > didn't note any detectable RPM change. The intake is stock and there > is a "normal" filter in place. I did try a K&N filter way back when > before deciding it was of no value. That was a long time ago and the > MAF has been cleaned with CRC MAF cleaner since then. Another freeze > frame had RPM at 2521 and MAF at 7.152 lb/min. How are your brakes working? > > > > > >> "Pete C." wrote: >> >>> '97 Chev K3500 7.4L >>> >>> Been chasing after the source of intermittent P0171/P0174 (always >>> both set) for some time without success. I'm running out of ideas >>> on what to check now, I don't have a full feature scan tool so I >>> can't perform all the possible checks. Some of the possible items >>> seem to not be applicable due to it always setting both codes, i.e. >>> exhaust or HO2S issues not likely since it's dual exhaust with dual >>> cats. >>> >>> I've replaced the fuel pump recently and the tank interior was >>> spotless, so clogging / contamination is not likely. I just >>> replaced the FPR and it's filter screen was clean as well. The FPR >>> did fix pressure leak down on pump shutoff, but that seems to not >>> have been a significant issue. >>> >>> I did plugs/wires/cap/rotor while I was at it this last service >>> Saturday, and the removed plugs all had moderate tan deposits that >>> seem consistent with the 130k or so on them. I also cleaned the IM >>> passages and ports while things were apart. >>> >>> I do have freeze frame data from the trouble codes as noted below: >>> >>> Closed loop / closed loop >>> Calc. load 19.2% >>> Coolant temp 167F >>> ST1 0.7% >>> LT1 24.9% >>> ST2 1.5% >>> LT2 24.9% >>> MAP 17.4 in/hg >>> RPM 2521 >>> MPH 65 >>> MAF 7.152 lb/min >>> TPS 20.7% >>> >>> No trouble codes other than the P0171/P0174 have ever been set. >>> >>> Any ideas where else to look? >>> >>> Thanks!
From: aarcuda69062 on 20 Jul 2008 09:41 In article <1Gxgk.33463$ZE5.8416(a)nlpi061.nbdc.sbc.com>, "W. Stief" <none(a)sbcglobal.net> wrote: > > Well, I sprayed some B12 around the IM while the engine was idling and > > didn't note any detectable RPM change. The intake is stock and there > > is a "normal" filter in place. I did try a K&N filter way back when > > before deciding it was of no value. That was a long time ago and the > > MAF has been cleaned with CRC MAF cleaner since then. Another freeze > > frame had RPM at 2521 and MAF at 7.152 lb/min. > > How are your brakes working? Why would his brakes cause a 2 lean trouble codes?
From: Steve W. on 20 Jul 2008 10:53 aarcuda69062 wrote: > In article <1Gxgk.33463$ZE5.8416(a)nlpi061.nbdc.sbc.com>, > "W. Stief" <none(a)sbcglobal.net> wrote: > >>> Well, I sprayed some B12 around the IM while the engine was idling and >>> didn't note any detectable RPM change. The intake is stock and there >>> is a "normal" filter in place. I did try a K&N filter way back when >>> before deciding it was of no value. That was a long time ago and the >>> MAF has been cleaned with CRC MAF cleaner since then. Another freeze >>> frame had RPM at 2521 and MAF at 7.152 lb/min. >> How are your brakes working? > > Why would his brakes cause a 2 lean trouble codes? Vacuum leak through the booster? -- Steve W.
From: Pete C. on 20 Jul 2008 11:05
"W. Stief" wrote: > > Pete C. wrote: > > mr158912 wrote: > >> > >> it seems to me you have a vacumm leak of some sort either intake > >> plenium/manifold gsaket or egr valve and maybe evan a pcv system > >> leak > >> but looking at your posted data even without o2 data i must ask if > >> you have a cold air intake kit with a k&n filter the oil from them > >> plays hell with the maf sensors > >> i would expect to see a little more maf signal at 1400rpms > >> mike the days of your kind of repairs and troubleshooting are going > >> away fast > > > > Well, I sprayed some B12 around the IM while the engine was idling and > > didn't note any detectable RPM change. The intake is stock and there > > is a "normal" filter in place. I did try a K&N filter way back when > > before deciding it was of no value. That was a long time ago and the > > MAF has been cleaned with CRC MAF cleaner since then. Another freeze > > frame had RPM at 2521 and MAF at 7.152 lb/min. > > How are your brakes working? Seemingly just fine. They are due for service when I find a free weekend (really when I have the ambition to press out studs), but no indication of sticking. Last time I put the jack under the truck and tried turning the wheels by hand there was no apparent drag, which is what I presume you're getting at. I'll check again when I get a chance a bit later today. |