C4 project
Thread Starter
6th Gear
Joined: Mar 2018
Posts: 6
Likes: 0
From: New Jersey
C4 project
I bought my 1st project Corvette. It's a 1991 C4 with the automatic transmission and 350 eng. The engine and tranny is already out, my plan is to rebuild the motor with a larger cam, roller rocker arms and a few other up grades, nothing major. My question is what do I need to do to the ECM if anything when making changes to the internal engine components?
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
81- 93 Corvettes used replaceable PROM (chip) for programming. You will need to "Datalog" and send files to "Tuner" to make PROM can take several trys. Other would be a dyno tuner who still burns the early chips. Last would be tuner friendly stand alone.
Le Mans Master
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From: Akron Ohio
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Check out PCMofNC for the mail order tune. Alvin does my race car tune by mail and it works really well. All you need to do it datalog some warm up, driving around normal, and a few wide open throttle blasts through the gears. Send him the file and he can adjust the tune as needed.
Team Owner
Joined: Jul 2004
Posts: 28,332
Likes: 3,247
From: Hartford WI
I bought my 1st project Corvette. It's a 1991 C4 with the automatic transmission and 350 eng. The engine and tranny is already out, my plan is to rebuild the motor with a larger cam, roller rocker arms and a few other up grades, nothing major. My question is what do I need to do to the ECM if anything when making changes to the internal engine components?
Have you called around the area to see which place has a dyno facility to take care of that for you? The C4s are getting harder to find places that want to screw with it. They probably will hook up the car and run it to see what is the best power you can get out of it and maybe try use their sniffers to make sure it will have some semblance of passing emissions if you need to. Your next option is to find someone you like who does datalogging so they can make the necessary adjustments to the ECM. After that, it's "Guess A Tune" time where you tell them what you have and they guess what it needs.
OTOH, if you are really going to make changes every couple of months or so, I would suggest you invest in dyno time and tuning hardware and software so you can DIY. If not, one of the above solutions should work.
Thread Starter
6th Gear
Joined: Mar 2018
Posts: 6
Likes: 0
From: New Jersey
Check out PCMofNC for the mail order tune. Alvin does my race car tune by mail and it works really well. All you need to do it datalog some warm up, driving around normal, and a few wide open throttle blasts through the gears. Send him the file and he can adjust the tune as needed.
Thread Starter
6th Gear
Joined: Mar 2018
Posts: 6
Likes: 0
From: New Jersey
T
Unless the cam is so close to stock that the ECM can compensate, you are going to need to get a tune or at best, it might run ok but act up at some spots. At worst, well.....
Have you called around the area to see which place has a dyno facility to take care of that for you? The C4s are getting harder to find places that want to screw with it. They probably will hook up the car and run it to see what is the best power you can get out of it and maybe try use their sniffers to make sure it will have some semblance of passing emissions if you need to. Your next option is to find someone you like who does datalogging so they can make the necessary adjustments to the ECM. After that, it's "Guess A Tune" time where you tell them what you have and they guess what it needs.
OTOH, if you are really going to make changes every couple of months or so, I would suggest you invest in dyno time and tuning hardware and software so you can DIY. If not, one of the above solutions should work.
Have you called around the area to see which place has a dyno facility to take care of that for you? The C4s are getting harder to find places that want to screw with it. They probably will hook up the car and run it to see what is the best power you can get out of it and maybe try use their sniffers to make sure it will have some semblance of passing emissions if you need to. Your next option is to find someone you like who does datalogging so they can make the necessary adjustments to the ECM. After that, it's "Guess A Tune" time where you tell them what you have and they guess what it needs.
OTOH, if you are really going to make changes every couple of months or so, I would suggest you invest in dyno time and tuning hardware and software so you can DIY. If not, one of the above solutions should work.
Thread Starter
6th Gear
Joined: Mar 2018
Posts: 6
Likes: 0
From: New Jersey
Team Owner
Joined: Jul 2004
Posts: 28,332
Likes: 3,247
From: Hartford WI
I must prefer someone do. It on a dyno so if start looking. C4s are considered old and there are less people doing it than used to be. Get several choices
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