K-Spaz

I replaced the PCM in my car with one from another 98 but it was a rear EBCM car where mine is in the front. I've got an odd issue right now where when I log the car in HPTuners it only fills in half the rows of the tables with a MAP value vertical axis. I'm using HPTuners 3.2.xxx (recent) and the tune was read from the 1998 car before I ever touched anything or the PCM went bad. Then, I replaced the PCM and got a fresh bone stock tune from ACDelcoTDS which was exactly the same tune as I had before, byte for byte (as would be expected since it was VIN specific). Rewrote my new PCM w/New Vin# using my Tech2, and off I went. The car started and I proceeded to attempt tuning it. learning as I go of course.

I just looked back at logs read before the PCM died and those populate cells in the tables the way you would expect. Going all the way up to 100 on the kPa scale. Anything logged after the new PCM was installed shows a max of 45kPa, clearly only showing half the values, as if one is one bar and the other is two. I have no idea. The car appears to run 'ok'.

If I open the tune from the original PCM in the car, it says 2 Bar OS. If I look at the ones pulled from the new PCM, they also say 2 Bar OS. So, I am lost here. I was under the impression that the 97/98 cars were a 1Bar OS. I put in a new MAP sensor and still have the same logging issue. Asking HPTuners has been fruitless.

On the recommendation of another forum member I've downloaded the older version of HPT but didn't install yet. I'd like to investigate this a little more first. What I don't understand is that the tables only show values for a 1 bar OS but the OS tab in HPT says it's a 2 bar. And now I'm thinking that the PCM itself is not like the original. But for whatever reasons, it seems to run ok. Needs some tune work yet of course but its certainly not inoperative by any stretch.

The new MAP sensor I put in is a SU1176. It didn't change any of this.

Here's a pic of the original PCM which I really don't think is dead, but won't function at all and says error communicating to the TAC module.

Cliff8928

Do you have a screenshot of the HP Tuner screen?

This might be better asked in the Scan & Tune forum....

K-Spaz

There is one in the S/T forum. I've just yesterday purchased another PCM with the same part # as the original shown above. I have a suspicion that when that gets here it's going to resolve the issue (provided I didn't get hosed with a bad one).