I just replaced my 1987 2.8v6 engine, transmission and underhood wireharness with a 1990 4.3v6. I bought a new computer for the 1990, a new map sensor and of course the 4.3 was brought to the machine shop for the heads and block. My question is I put an MSD distributor on it with coil to get better performance and I am having high idle, busting out on the top end and some times it loads up at the longer red lights. I have not replaced the old throttle body and was wondering if it was the problem?
Throttle Body on 1990 GMC S15 Jimmy
The sensors are different for a 4.3. And yes so is the throttle body. Put everything you can from the 4.3 on the vehicle. You may try the stock distributor to check if the problem is somehow MSD related. this could be a bit tricky to iron out. the computer systems and wiring are very specific to each motor, even if the motor was available for that year.