I have a 94 cavalier w/ the 3.1 I ordered a 93 ECM with a chip, because I am told my 94 ECM is not chipable. I installed the 93 ECM w/ chip and my car would crank, but would not start, so I hooked a snap on diagnostics computer to my car, and it was not reading that a ECM was even there, so I turned the chip the opposite way that it was installed thinking that possibly the people I purchased it from installed the chip wrong. Once I did that the snap on diagnostics computer was reading that an ECM was there, and my car did start, however it would stall if I let up off the gas, and just about every error code imaginable popped up on the snap on diagnostics computer. Does anyone have an idea what could be wrong? The only thing I can think of is that they sent me a bad ECM.

the 94 computer is the same as the 93 computer, whoever told you it wasn't is on drugs.


try the 94 ecm with the new chip.. chances are that you burnt up the eprom by having it installed backwards, the computer is probably running in limp mode.