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This is getting ridiculous! Car lays over goes lean

J

J57ltr

New member
05' GTP car came with questionable modifications 3.4"'pulley slightly larger exhausts airbox is loose.

the car will not go into boost and when it does it seems to get to about 5psi if I ease into it.

i have put the car back to stock 3.8" pulley, honeycomb installed into the MAF, knock sensors replaced, stock airbox back in place everything. The ONLY thing I haven't changed is the exhaust and I put in a 180* thermostat while changing the knock sensors since clean water is a lot tastier than coolant.

The deal is if I lay into it even from a roll into it. The car goes dead lean and the ignition drops back to single digits. This has been driving me crazy for almost a month, and it seems no one here can figure it out. I am going to work on making a chart of what's happening. I have a few logs of what's going on, but it is difficult for me to get all the parameters on a single graph because of the scale would make everything unreadable.

things I have checked:

fuel pressure- 65psi all day every day
new plugs and wires (106's)
new knock sensors (one was false tripping)
MAF cleaned
MAF responds properly
CAT isn't plugged


i keep getting a O2 sensor low output. The output goes low only when I get on it. The code says for 2-4 minutes but I believe this is either different, wrong or a misprint. Because it happens in a 2-4 second run.

Im stumped

Jeff
 


Are there any other mods on the car? Cam, headers, rockers? Was the car previously tuned? All i got out of what you said was the problem with the car is it only gets to 5 psi boost. Makes me think bcs.
 
The car is totally back to stock with the exception of the 180*'tstat and a ZZP 3.8" pulley. I have bypassed the bypass control and it sent the engine into reduced engine power, the DBW will also shut down the throttle to not allow enough air to go into boost. Even fully disconnected it will not go into boost.

jeff
 
So the car is falling on its face under throttle? Vac leak, bad maf, or new motor (do a compression test)

Eh just read the o2 sensor part. Seems pretty obvious. Fix whats broken and go from there.
 
I don't think it would O2 as it operates normally swinging from rich to lean under NA conditions, but when I try to go into boost it will go to 0v and stay there until I let off the gas, then it goes dead rich and unless I touch the throttle it swings from dead lean to dead rich. Usually by this time the MIL is set.

So to recap after a roll on the throttle and if I do it gently enough I can get to about 5psi but any more and boost drops to 0. At this time I am fully on the throttle the engine lays over as the 02 goes dead lean and timing backs off sometimes to -2*. I will keep it floored through 1st and let off just after then2nd shift. last night I reset the MIL from the Torque app
while driving and th O2 went back to normal operation.'I understand this is a narrow band O2 so to me it is operating correctly. I don't see the reason the engine goes lean that seems to be the issue.

i am going to do a compression check, but this engine runs like a sewing machine. I have a forklift that has a 100psi cylinder and I can hear it. My gauge is at work, but I might bring it in the shop and check it out next week. It starts on a dime.

Jeff
 
I've checked for all the vacuum leaks it could have, went through it thoroughly, replaced several lines and used a tywrap gun to properly hold all lines.'

Jeff
 


No ticking or anything, I was under it on ramps and didn't have any ticking. Never tried seafoam is there a tutorial?

Jeff
 
Yea, but it's not that hard. Hold throttle at 2,000 RPM while pouring about 1\3 of the bottle into a vacuum line, then shut the car down for 10-15-20 min. or so. Fire it back up and watch for smoke. It should be a pretty good smoke show. Some say it's bad for the coating on the rotors so I use the vacuum T below the supercharger, better safe than sorry.
 
Hmm my wife isn't good at instructions. May have to get the neighbor to hold the throttle. I've got to run some errands but I charted the last log and have to post them might be easier to see what's going on.
 
It's not meant to find exhaust leaks but it helps. It's meant to clean. It cakes itself to carbon then when you start it after the 15-20 minutes it burns it all off.
 


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