Hello! This is my first time to this site. What a great group of people that post here! I've found a great amount of information through the search button. I can't find a solution for an issue I'm currently having. I have a number of 3800 Grand Prixs (5) and a Bonneville SSEI that I and an employee drive for my business. 3 of my Grand Prixs have 260,000 plus miles and run great. I'm starting to pirate parts off of a few and I do the maintenance for the company vehicles.
I recently had 4th gear go out on my '98 Grand Prix GT (3800). I bought a wrecked '00 GT with a newly installed engine (6k miles) and transmission (12k miles) and swapped in the engine and transmission into the '98. I did not swap PCMs and the car fired right up and ran great with no SES lights or anything. 2 weeks later the car stumbles or stutters only after going into 2nd gear when the throttle is partial or light throttle. It feels like the axles are bad as the whole car shakes a bit. Thinking axles I changed both sides today and the problem seems to persist. It does not do this all the time, but appears to be getting worse. My question is do you think I need to swap in the '00 PCM to match this combination? I'm unsure if the shaking is an issue with the PCM, transmission or differential. The output shafts from the differential have about an 1/8 inch play in them but since this issue only happens with low RPM in second gear I'm wondering if the PCM is having an issue with a shift point or pressure. I would assume the differential would cause issues in all gears. Maybe the second gear clutches are grabbing and slipping? Or the Covertor Lock is going lock/unlock? I'm not sure exactly what is causing this. In doing some research I've read the PCMs are different in regards to the MAF sensor between '98-'99 and '00-'03. Is this correct? If so could this cause the engine to misfire at low RPM under load in second gear?
Also I have am thinking of getting a scan tool to not only scan but make changes in shift points, ect. What do you guys recommend for a tool to work with all my vehicles ('98-2000) 3800s? I also have an '02 Escalade. Is there a scan tool that allows adjustment to this vehicle without extra expense as well? Thank you in advance for your time.
