my 87 gn has a very rough idle and the performance isn't where it should be. The car has alot of new parts such as: walbro307 fuel pump, hot wire kit, accufab fuel reg., new coil pack, 8.5mm wires, mass air pipe w/ 9" k&n air filter, 2.5 exhaust, terry houston downpipe, stock turbo, stock injectors, new timing chain, cam sensor, crank sensor, Iac valve, vaccum block, 160 thermostat. I have a jay carter street93 chip and the car would have no knock @wot but the power wasn't there.I put the factory chip back in the car and the car feels good but i had 4 degrees of knock. another problem came up which is when i launch the car pulls hard untill 15psi then it drops right back down to 10psi and slowly increases as the mph goes up. my scan values at idle are: AF 7, L8 46-52, BAT 13.8, INT 122-130, BL 115, CLT 171,ATS 92, TPS .36, IAC 09,fuel 39 psi static. the scan value for wot are: AF 240, L8 255, BAT 13.0, INT 128, BL 125, CLT 189, ATS 85, TPS 4.72, IAC 80, O2 .792 3.8 degress of knock @58mph and 78mph. the same problem with the boost it went to 15psi and droped to 10psi.
Any help will be great!!!!!!!
I would start with the TPS. At idle you should be around .42-.46 not .36 that you reported.
Check out the IAC reset procedure as well.
After resetting both the IAC and TPS see how it responds and go from there.
Check for inconspicuous leaks in the intake track. On my dad's GN, it turned out that half the gasket between the turbo inlet bell and turbo was missing.
Also check that the IAC passages are clean and un clogged.
Also check that the EGR valve is not stuck open. EGR generally shuts off or down at idle, and if not functioning properly could cause this idle situation.
As for the "variable Boost" check the wastegate actuator and it's plumbing.
Hope some of this helps.
Craig
hi guys thankx for the help. I have reset my tps to .42 at idle and wot @ 4.72. I also re-adjusted my iac valve and the #'s are there according to the chat on this web page. I also came across another problem my exhaust manifold is leaking. When i pulled off the drivers side manifold, the pipe between #3 & #5 is cracked. Now i have to look into either welding this manifold up or new set of headers?? once againg thankyou for the help
Weld up the stockers. Aftermarket headers aren't necessary until you're going very fast, and may hurt you on a fairly stock car. Try to find someone who knows what they're doing. It also might be best to have the header bolted to an old head when you weld it to insure it is stressed as it would be on the car.