Hey ya'll new memeber here and recently a first time owner of a 2001 monte carlo ss. Bought the car from someone I go to school with for $300. Figured it was a steal for how clean it is. Pretty much bought it as a project car. One of the previous owners did an engine and transmission swap and it now has a supercharged 3.8 in it. I got it and it ran really rough and didnt like to start and it needed a passenger cv shaft since it wasnt the right one for the transmission. So got the right cv shaft in and replaced the spark plugs and put new crank sensor in and now it runs really smooth. But when I first start it when it's cold its runs a little rough. But after a minute or less it smooths out and runs great. Cant seem to figure out what is wrong there. Also I only have one gauge that works and thats the volt gauge. I do know why the speedometer doesnt work along with the oil pressure gauge but not sure on the tach fuel gauge and temp gauge. Never really dealt with any problems like these before as ibe really only owned older chevy trucks that are easy to work on and figure out problems. But if anyone has any input on what my problems would be thatd be perfect. Thanks im advance for any help. It would be greatly appreciated so I can start driving the car.

 

I don't know the answer to your problem but welcome to the forum!!

 

when the engine and tranny were changed, was the pcm changed? You may need a tune to get everything working the way it should. Just a suggestion

 

Where is the pcm located? Running my buddies scanner on it it showed the vin and its not the same and said it was for a car that had a 3.1 v6 in it. Runs fine until you get on it then it seems like it has a miss but then its fine when you let off.

 

The pcm is in the stock air box under the air filter, it should not come up as a 3.1 it should be a 3.8.
You may have to flash the pcm with a tuner to run as a 3.8 or pick up a used one from the wreckers that is actually from a 3.8 as if it's not tuned properly for the motor you are gonna have some serious issues, especially if it's supercharged.

ZZP may be able to email you a flash file for the pcm?

The Maniac, one of the members on here offers a pcm service, he may be able to assist here is a link to his post on his pcm service, if nothing else he may be able to direct you to someone that can, he is a very knowledgeable guy and helps people out whenever he can

https://montecarloforum.com/forum/pr...e3/#post658521

this would also explain why your gauges aren't working properly as they are not tuned for your motor/car. Also your tranny will not work right either as I believe it also needs to be tuned for the motor and gears, the supercharged tranny has a different gear ratio I believe

 

Alright thats where I figured it was. I think im gonna get one from tuwthe junk yard since im pretty sure theres a few out there still. But if I dont find one ill probably just have this one flashed if I can. But the trans shifts perfect and goes through all the gears. But thanks for the advice. Now I can get back on track to getting this thing driveable again