I've got a 93 maxima w/ a GT30r Turbo, Jwt ECU, 370cc injectors, z32 MAF, and an intercooler. The problem i'm having is that when u first start it, it runs awesome. Now when it gets to normal Temp.(after a couple of mins), it runs horrible, as if timing has been pulled back. It feels extremely weak. Now i've checked for codes, changed my TPS, Knock sensor, coolant temp sensor, tried another MAF, but to no avail. It seems like it runs well during open loop and just goes to S*** during closed loop. Does anyone have any idea what it may be? Is there a chance that the timing maps on the ecu are incorrect during closed loop? If so, is there any way i can keep the vehicle in open loop? This thing has been so frustrating for so many months, any help would be greatly appreciated. TIA

Sam

 

Is the ecu tuned for the injectors and z32 Maf..

 

yeah, it's tuned for the 370cc injectors, z32 maf, and turbo.

 

So you are saying it still does ok at WOT but at cruising/partial throttle it is having problems?

 

Brad 92SE was having what sounds like the same problem. He found that the knock sensor was hearing knock when there was none. He disconnected it and it cured the problem. Try that first. Listen for knock!!!!!!!!
I run my car in Open loop all the time. My car is a VG. I just keep the O2 sensor disconnected which keeps it in open loop. Bernard said there's a code I could change to keep it in open loop perminaltly through "Live Edit".
Hope this helps, Scott

 

Neal, what i mean is when i first start the car it runs awesome(all the way to redline), then when it warms up(closed loop), timing feels like its retarded. My low end is gone(before boost) and so is everything else. It feels extremely weak.

Scott, I bypassed the knock sensor w/ a resistor and that didn't work, i also bought a new knock sensor and that didn't work also. I disconnected it and that didn't work either. I think i'm gonna try disconnecting my O2 sensor to see if that helps. I really think it might be the timing maps in my jwt ecu.
Any other suggestions? Thanks for the help guys.

Sam

 

Well your car goes into open loop when you floor it (actually when you get above a certain throttle position, just can't remember what that percentage is). So I don't think it is an open vs closed loop issue. I don't really have any help to offer beyond that, but your car should definately be in open loop if you floor it.

 

bad z32 maf?????

 

do you have a spare stock ecu. if so i would put it in and see if it starts. if it does start i would drive it around (dont get into boost) and see if it still getts "slower". if its still slow its not you JWT and youve got another problem.