So I put a new ecm in my 94 sts and now the trans shifts hard. I put the stock ecm in the car and it shifts great. I put the PROM back in the new ecm and it shifts hard. anyone had this?
thanks

Why are you replacing ecm? Transmission is controlled by ecm. Possibly bad or incorrect ecm.

The ECM is a GM reman ECM. I replaced it due to an injecter not fireing. Now the motor runs good (with the new ECM) but the trans shifts hard. I put the stock ECM in and #6 injecter will not fire but the trans shifts great
thanks

Still maybe bad ecm, after all they are rebuilt. Fuel injector driver will not be in the same part of ecm as trans controls.

I was thinking the PROM was not holding the trans shift values.

Prom won't lose calibration from ecm to ecm it is permently burn't in. GM prom's program can not be over written., It's not an E-prom which can be.

so you think it is a bad reman ECM?

ORIGINAL: rjs12182

so you think it is a bad reman ECM?


ORIGINAL: slowroll

Still maybe bad ecm, after all they are rebuilt. Fuel injector driver will not be in the same part of ecm as trans controls.

I got a 2ed ECM from the junkyard they did an interchange and it is out of a 95 olds aurora. I put my prom in it from the stock ecm started the car. The car ran but has "no pcm data" I checked the prom it was in good.
So my stock ecm will not fire injector #6 but everthing else works
The gm reman ecm will fire injector #6 and the car runs great but the trans shifts very hard
The interchange ecm (95 aurora) the car just runs in defalt mode and has "no pcm data"

any idea's?

Was reman ecm new or junkyard also? Do numbers on replacement ecms match original ecm?

the reman ecm is new gm #88961146. the junkyard ecm and my stock ecm DO NOT have the same service number but the junkyard interchange said it would work. all 94 95 northstars have service numbers 161xxxxxxx gm #88961146 is the replacement for the 161xxxxx numbers .....or that is what i was told
thanks

Non-matching used ecm is cause for no pcm data. Talk to dealer who sold you reman ecm explain engine now runs on all 8 but trans shifts hard. They should warranty it and exchange ecm.