I have a 1990 IROCZ. It was originally a 5.0TPI/5speed. The car has had the engine bay gutted of all electronics,and harnesses. It is now a 5.7 w/gigantic Holly, Wolrd products heads, fancy short block, and Turbo 350 trans w/tiny race converter.

I was about to convert the car back to a sort of stock configuration. 5.7 TPI TH700R4, and put all of the stock wire harnesses, etc., back into the engine bay.

Well I have found out that in 1990-1992 GM changed from, or to a "speed density" system. Whats up with that? I know where a complete set up is. But the owner is not sure if it is 1989 or 1990.

How can I tell the difference if the engine is not in the car?

Thanx, andyZ28

 

if the setup didnt have a MAF sensor but had a MAP sensor instead, its one of the newer speed density systems. You can also check to see what ecm it is, that should tell you. IIRC they changed ecms when they went to speed density. Personally, id jsut use the carb setup. Sounds like its a whole lot faster then a stock tpi setup would be. The stock tpi intake doesnt flow that well and is only suited to midrange power. fromt eh sound of it teh stock tpi setup would gag the motor you have now and not be well matched.

 

I am going to change the engine anyway. I got the car with a dropped valve on #8 cylinder. It broke the engine block.

What would be the part# on the 5.7 TPI Speed Density ECM?

Thanx, andyZ28

 

In 1990 they went to the 7730 ECM. Same as the FWD MPFI 3.1/3.4's.

Usually the MAP sensor will be located beside the TPI plenum. If it's a MAF car the front intake snout should have a MAF sensor at the end, if it's still there.