P0171 & P0174, searched, running out of ideas 04 LS1
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P0171 & P0174, searched, running out of ideas 04 LS1
I have an 04 GTO LS1 pullout in my 93 RX7. I have only had it running and on the road a short period of time, and I keep getting these 2 codes along with some symptoms. I have searched and searched and searched, I know all the basics, header flange leaks, vacuum leaks, bad MAF, etc. Let me run through my symptoms, add actions i have taken to date, and toss it out there for other ideas. First, here are some pictures showing the intake and exhaust setup:
Here is the current intake setup. Stock MAF, stock TB, stock (LS6) intake.
here you can see the long tubes, and the O2's are right before the V-bands, after the merge collectors:
Symptoms:
P0171 and P0174, Lean codes, both banks
Starts up quick, idles good, but will stall if you "blip" the throttle, sometimes stalls when coasting to a stop with clutch in. Exhaust smells extremely rich at idle.
Long term fuel trims for both banks up in the 20-24% range at idle. MAF, MAP, O2's really seem to be reading ok, I haven't logged any since last year when i first ran the car. I will try and do some logging and post up what i get.
LTFT will come back down to earth when you unplug the MAF, and also when you drive the car, they seem to come back down. They are really only out of whack at idle, but i dont have a lot of driving data.
Here is the strangest symptom: If i am watching the LTFT, and the car is idling, and the electric fans kick on (PCM triggered), the LTFT will come down during the time the fan is on. After the fan shuts off, they go back up.
When you first start the car, you do get some exhaust fume smell from under the hood, but i dont hear any header leaks, and i dont see any carbon tracking. could be leaking welds in the headers, leaks at flange or at v-bands. I cant hear or see one, just smells like one. Could a minor leak really cause the codes? What are the chances i have leaks at both headers, especially after removing, milling, and reinstalling with new GM gaskets?
Actions taken so far:
Removed headers, had header flanges milled. Replaced header gaskets with new GM MLS gaskets. ARP header studs.
O2 sensors are new OEM sensors installed during build. less thank 250 miles on them.
MAF: cleaned stock maf, bought replacement used MAF, confirmed to work, no change.
Replaced intake gaskets, Throttle body gasket, and PCV hose.
Small vacuum line on back of intake is capped, large goes to brake booster. Have tried plugging that with no change.
EVAP removed and tuned out, port on intake capped.
Since it is an 04 GTO engine, no EGR. PCV system is LS6, so it has only 2 lines, one from valve cover to TB, one from valley cover to intake. that is the one i have just replaced. Vacuum cap on rear drivers side valve cover installed and intact.
Sprayed the engine with carb cleaner to look for vacuum leaks. when that didnt show any, I built a smoke machine, pumped smoke into intake manifold. Saw no leaks.
As you can see. I have been exhausting all the typical culprits for these codes. All symptoms seem to point to vacuum leak, but i have basically tried everything.
Some theories i have heard:
1: the short OTR intake setup and long tubes, with no cats and a free flowing exhaust, means i just need a tune, MAF too close to TB, o2 sensors too far from heads. I find this tough to believe, as the engine is stock otherwise, and they LTFT's come down when driving. It is really only and issue at idle. Many GTO owners have CAI or LT's, and have more mods than me.
2: I screwed up some wiring when i was shortening the engine harness. I would buy that, but why would it not be an issue during driving, or when the fan came on?
3: I have a vacuum leak/ Header leak, and i am too dumb to find them. I buy this, but where else do i look? why didnt my smoke machine pick up the leak?
4: I read one guy who had bad o2 extensions. How would i determine this? resistance measurement?
Next steps:
Pull headers, check for header leaks, change out o2 sensors, use REMFLEX header flange gaskets.
Unhook brake booster,
Do some data logging. I know it is tough to help me without seeing some data. I will work on this and post up something.
Get a tune. I am pretty convinced i have something mechanically wrong. Wouldnt i be asking for trouble tuning without solving the problem.
I am open to suggestions, even radical ones. I feel like i have tried everything i have come across in my searching. I did pick up an F-body PCM, as I was wondering of the GTO pcm is overly sensitive to things like O2 location and MAF location. I havent put it in, as it would require re-wiring the o2 circuit. (GTO grounds the O2's through the PCM, F body does not).
Here is the current intake setup. Stock MAF, stock TB, stock (LS6) intake.
here you can see the long tubes, and the O2's are right before the V-bands, after the merge collectors:
Symptoms:
P0171 and P0174, Lean codes, both banks
Starts up quick, idles good, but will stall if you "blip" the throttle, sometimes stalls when coasting to a stop with clutch in. Exhaust smells extremely rich at idle.
Long term fuel trims for both banks up in the 20-24% range at idle. MAF, MAP, O2's really seem to be reading ok, I haven't logged any since last year when i first ran the car. I will try and do some logging and post up what i get.
LTFT will come back down to earth when you unplug the MAF, and also when you drive the car, they seem to come back down. They are really only out of whack at idle, but i dont have a lot of driving data.
Here is the strangest symptom: If i am watching the LTFT, and the car is idling, and the electric fans kick on (PCM triggered), the LTFT will come down during the time the fan is on. After the fan shuts off, they go back up.
When you first start the car, you do get some exhaust fume smell from under the hood, but i dont hear any header leaks, and i dont see any carbon tracking. could be leaking welds in the headers, leaks at flange or at v-bands. I cant hear or see one, just smells like one. Could a minor leak really cause the codes? What are the chances i have leaks at both headers, especially after removing, milling, and reinstalling with new GM gaskets?
Actions taken so far:
Removed headers, had header flanges milled. Replaced header gaskets with new GM MLS gaskets. ARP header studs.
O2 sensors are new OEM sensors installed during build. less thank 250 miles on them.
MAF: cleaned stock maf, bought replacement used MAF, confirmed to work, no change.
Replaced intake gaskets, Throttle body gasket, and PCV hose.
Small vacuum line on back of intake is capped, large goes to brake booster. Have tried plugging that with no change.
EVAP removed and tuned out, port on intake capped.
Since it is an 04 GTO engine, no EGR. PCV system is LS6, so it has only 2 lines, one from valve cover to TB, one from valley cover to intake. that is the one i have just replaced. Vacuum cap on rear drivers side valve cover installed and intact.
Sprayed the engine with carb cleaner to look for vacuum leaks. when that didnt show any, I built a smoke machine, pumped smoke into intake manifold. Saw no leaks.
As you can see. I have been exhausting all the typical culprits for these codes. All symptoms seem to point to vacuum leak, but i have basically tried everything.
Some theories i have heard:
1: the short OTR intake setup and long tubes, with no cats and a free flowing exhaust, means i just need a tune, MAF too close to TB, o2 sensors too far from heads. I find this tough to believe, as the engine is stock otherwise, and they LTFT's come down when driving. It is really only and issue at idle. Many GTO owners have CAI or LT's, and have more mods than me.
2: I screwed up some wiring when i was shortening the engine harness. I would buy that, but why would it not be an issue during driving, or when the fan came on?
3: I have a vacuum leak/ Header leak, and i am too dumb to find them. I buy this, but where else do i look? why didnt my smoke machine pick up the leak?
4: I read one guy who had bad o2 extensions. How would i determine this? resistance measurement?
Next steps:
Pull headers, check for header leaks, change out o2 sensors, use REMFLEX header flange gaskets.
Unhook brake booster,
Do some data logging. I know it is tough to help me without seeing some data. I will work on this and post up something.
Get a tune. I am pretty convinced i have something mechanically wrong. Wouldnt i be asking for trouble tuning without solving the problem.
I am open to suggestions, even radical ones. I feel like i have tried everything i have come across in my searching. I did pick up an F-body PCM, as I was wondering of the GTO pcm is overly sensitive to things like O2 location and MAF location. I havent put it in, as it would require re-wiring the o2 circuit. (GTO grounds the O2's through the PCM, F body does not).
#5
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I am using a corvette fuel filter/regulator. It gives me 58 psi at the rail at idle
well, after 4 years of building the car, i can't exactly quit now!
#7
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Have you verified FP with a gauge on the rail? Also there is a version of the valley cover that doesn't have the built in pcv valve restriction. It requires a PCV valve in the loop back hose. If you use just a plain hose with that valley cover it will cause the problem you have.
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Have you verified FP with a gauge on the rail? Also there is a version of the valley cover that doesn't have the built in pcv valve restriction. It requires a PCV valve in the loop back hose. If you use just a plain hose with that valley cover it will cause the problem you have.
Here is the car:
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#11
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I had a similar issue in an old vette with a LS3 swap. The fans were actually blowing so much air on the air filter that it was messing with the MAF reading. I dont know if thats the case on your setup but its something to check especially if the fans are having an effect on your fuel trims. I wouldn't have believed it if I didn't see it myself.
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I had a similar issue in an old vette with a LS3 swap. The fans were actually blowing so much air on the air filter that it was messing with the MAF reading. I dont know if thats the case on your setup but its something to check especially if the fans are having an effect on your fuel trims. I wouldn't have believed it if I didn't see it myself.
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update on some things i did over the weekend. Still no data logs, my laptop battery crapped out so i cant log until i buy a new one.
I did pull the passenger side header, the OEM gasket did not appear to be leaking at all. no carbon tracking other than around the ID of the gasket. The v-bands also dont appear to be leaking. It is possible that the merge collector on the headers are leaking, but it is almost impossible to tell looking in between the 4 pipes. I also find it a little hard to believe that both headers are leaking when no one using these particular headers has had any issues.
I did pull the passenger side header, the OEM gasket did not appear to be leaking at all. no carbon tracking other than around the ID of the gasket. The v-bands also dont appear to be leaking. It is possible that the merge collector on the headers are leaking, but it is almost impossible to tell looking in between the 4 pipes. I also find it a little hard to believe that both headers are leaking when no one using these particular headers has had any issues.
#14
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I had a similar issue in an old vette with a LS3 swap. The fans were actually blowing so much air on the air filter that it was messing with the MAF reading. I dont know if thats the case on your setup but its something to check especially if the fans are having an effect on your fuel trims. I wouldn't have believed it if I didn't see it myself.
update on some things i did over the weekend. Still no data logs, my laptop battery crapped out so i cant log until i buy a new one.
I did pull the passenger side header, the OEM gasket did not appear to be leaking at all. no carbon tracking other than around the ID of the gasket. The v-bands also dont appear to be leaking. It is possible that the merge collector on the headers are leaking, but it is almost impossible to tell looking in between the 4 pipes. I also find it a little hard to believe that both headers are leaking when no one using these particular headers has had any issues.
I did pull the passenger side header, the OEM gasket did not appear to be leaking at all. no carbon tracking other than around the ID of the gasket. The v-bands also dont appear to be leaking. It is possible that the merge collector on the headers are leaking, but it is almost impossible to tell looking in between the 4 pipes. I also find it a little hard to believe that both headers are leaking when no one using these particular headers has had any issues.
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I pulled the passenger side extender when I had the header out and measured the resistance on all 4 wires. There was no resistance. I didnt want to remove them until i did some data logging. I want to see what the 02's are doing with them installed, then I can try removing them and seeing if things change.
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i am still battling this issue. I did some data logging when i took it for a drive yesterday, unfortunately my laptop died before i could save the data.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
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i am still battling this issue. I did some data logging when i took it for a drive yesterday, unfortunately my laptop died before i could save the data.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
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Ok I have an 04 Ls 5.3 flex fuel in a 92 s10 and I'm in the same boat with u. I have been trying to figure out why I'm having these issues as well. I have done everything u have also and according to the efilive program everything seems to be running fine under load but at idle my o2 sensors are at about 13-18% and under load they lower out below 6%. I have everything stock on this truck setup except the headers that came with the swap kit. Have u made any progress with ur car?
#19
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???
i am still battling this issue. I did some data logging when i took it for a drive yesterday, unfortunately my laptop died before i could save the data.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
here is what i noticed watching the readouts:
at idle, both LTFT's are about 15-19 (15 on bank 1, 19 on bank 2). O2's seem to be switching as they should.
When driving around, the LTFT's drop to low single digits when engine has load, including some decent acceleration runs. As soon as i let off the throttle, coasting in gear, the LTFT's peg at 25. SO basically, in high vacuum conditions, it has the problem.
I think it eliminates the O2 extensions as an issue. Seems to me to limit it to a vacuum leak or an exhaust leak is still top suspects.
We just fixed the exact same issue by replacing a leaking in tank hose...We found it w/ a fuel pressure gauge....
#20
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Ok I have an 04 Ls 5.3 flex fuel in a 92 s10 and I'm in the same boat with u. I have been trying to figure out why I'm having these issues as well. I have done everything u have also and according to the efilive program everything seems to be running fine under load but at idle my o2 sensors are at about 13-18% and under load they lower out below 6%. I have everything stock on this truck setup except the headers that came with the swap kit. Have u made any progress with ur car?
Last edited by 408-99-f; 09-02-2013 at 09:42 PM.