jeffp5

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).

Mike@Diablosport

iTrader: (2)

#4 seems to be a more common issue these days.
I see people getting $1500 headers that comes with junk O2 extensions that must have cost .02 cents all the time.

2xLS1

iTrader: (25)

What is the fuel pressure at the rail?

Raoul-Duke

iTrader: (6)

Damn with all the effort you put into finding this, My hat is off to you good sir. I hope you find the problem asap so you can be at ease.

I hate ****** codes.

jeffp5

Good to know it is common. The extensions actually came with the pullout, so the GTO that my engine came from must have had LT's installed.


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!

Raoul-Duke

iTrader: (6)

Never Quit! Just good luck.

oh and do you have any other pics of her lol

2xLS1

iTrader: (25)

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.

jeffp5

Yeah, I verified the fuel pressure with a gauge. The valley cover is stock GTO, and the hose routing is also stock. I actually was planning on disconnecting and capping all 3 lines (booster, TB-valve cover, and PCV) and seeing if anything changes.

Here is the car:

2xLS1

iTrader: (25)

What are the fuel trims while cruising at around 2000 rpm?

jeffp5

i believe they were closer to 10, but i am going by memory. Once it stops raining i will get the car out and do some data logging

LSX Power Tuning

iTrader: (4)

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.

jeffp5

good thought. My filter is right in front of my radiator, so it makes sense that the air moving could be having an effect.

jeffp5

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.

Mike@Diablosport

iTrader: (2)

Thats a very common issue on lots of Fords, when they use an open element filter under the hood as well...

Have you tried removing/replacing the O2 extenders??

jeffp5

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.

jeffp5

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.

408-99-f

Did you ever figure out this issue? I have done everything you have done. And I have the sama exact problem. Any help would be great I'm at my wits end.

vroque210

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?

Old Geezer

iTrader: (3)

The fuel psi question has been posed twice....Still no response that I can see.
We just fixed the exact same issue by replacing a leaking in tank hose...We found it w/ a fuel pressure gauge....

408-99-f

I figured mine out. Exact same problem. And yes my fuel pressure was ok. Few minor things that added up. Every thing I fixed it brought the trims down . First I had a leak from a crack inside the pcv grommet that would not show up on a smoke test due to the pressure vacuum differences. I went and made a home made catch can. Second I had a leak at the header merge on both sides bigger on the psssenger side. Only when hot ??? Had only checked cold before. Could not hear it. Causeing the split trims. I cut a pice out of the tube and welded the slip fit on the inside. Then welded the peice back on. I used the smoke machine to check. Third I cleaned my injectors (best I could, took the rail off hooked up a injector plug off another harness spliced in a switch, had someone key it up to put pressure in the system and released the pressure through the injector. And it worked, did it 3 times through them all and the pattern got better on one. Blew the junk right out.) Be carefull if you try this. The only reason i did it this way was because no one has the mechine to do it around here. They had sat with gas in the rail for a while. Then I replaced the o2s with new ones. Then I reset my fuel trims and took it out. No more problems. Next day I spanked a alleged terminator mustang. I really hope this helps you or someone out. I check my pm's every few days so if you have any questions ill do what ever I can to help. I'm the only ls guy in my area ( a sea of tuners and mustangs) so ill be happy to help someone lol. BTW I'm a tech at an indapendent repair shop and usually the rule of thumb is high trims at idle check vacuum. High trims at higher rpm's check sensors o2, maf etc. It does not always work, But I personally have fixed many cars starting with this