Hello guys,

been having a problem with my wifes 95 LT1 M6 vette. has been running perfect with the mods on it for about a year:

PP heads
PP intake
219/219 .560/.560 112 cam
LT headers
52mm TB
30 LB injectors
no cats
no EGR
no AIR
programmed by Ed Wright

symptoms... car will sometimes run perfectly for a day or two then without warning, it begins to miss stutter backfire shake and sometimes die when coming to a stop.

I ran PCMCOMM tonight for about 20 mile trip where the car ran perfect for the first half even after reaching normal operating temps for about 15-20 minutes. while this was running right, the Integrator L abnd Integrator R were both sitting between 126-130 fluctuating back and forth staying together, all other readings looked great. then the problems started and i noticed that the Integrator R went from the 126-130 to 195 and stayed there. this is when the car starts running terrible. I have replaced almost everything including injectors trying to hunt the issue down, and am now at my wits end.. can anyone give me any advise? also, i would like to do some real time scanning recording with datamaster and have used it on the past on my old laptop but cannot find the demo version anywhere any more! any one know where to DL any more? any help on this will be appreciated!

Chris

 

You need to record the fuel cell (02,03,04....10,14) and 16 is the idle cell. Look at the Lterms.. the fuel corrections that do not move. The Sterms as you stated fluctuate but I always get a better idea of whats happening looking at the Lterms. Also, make sure to record both left and right banks to rule out exhaust leaks and other problems associated with only one side of the motor.

What is odd is that you stated the integrators(i believe the same thing as Sterms in datamaster lingo) are 195 when stock they normaly max out at 160. So it appears Ed increase the max fuel correction considerably for some reason. If only the right bank shot up to 195 and the left stayed down around 130 then it is pretty safe to assume you have a rather large exhaust leak that is effectively "tricking" the PCM into believing the right bank is running lean.

 

thanks turbo Z,

I think i may have a slight exhaust leak. I will bemoving the O2 sensors closer to the collectors.. right now they are located about 3 inches past the collector flanges on the catback side. the only thing that gets me is that the dammed problem is intermittent. when the car starts acting up, it throws a cloud of black smoke out under acceleration and barely goes as high as 5000 RPM... when running correctly i can barely keep from hitting the rev limiter in 1st and second. the tuning from ed is old news.. i wish when i had it done about 2 years ago i had learned to tune myself, but it was just too overwhelming with my wedding schedule, i was ready for the car to come to life and he was a fast answer! oh well. anyone know if he locks his tunes, or should i be able to go in and do some tweaking on the PCM? again, any help appreciated!

Chris

 

I worked on a Camaro with the same problems, it turned out to be the intake gaskets. I replaced them and resealed the front and back with GM seal adhesive and the problem went away.

Scott