I decided to add a HP prom to my Z, I bought it from TBI chips. I noticed that it didn’t seem to do what I had hoped but didn’t seem to hurt anything. I than installed an overhead council, and an auto chromatic mirror with temp and compass. I then noticed that the oil gauge was bouncing all over the place and it would peg, this I thought was a problem with the gauge or the sending unit ok. I went to check the sending unit and saw that the ignition control mod had a broken connector, so I replaced it. After that, the car won’t run right at all intermittently, it would run right and than I would hit a bump and it would start running ruff again. Now I get a code 42 and it will barley run at all. I have tried a different ecm put the original PROM back in replaced the ignition control mode., got it to run right again, put all the wiring back together and than it wouldn’t run again.
HELP!!!!!!

 

Fixed it! The prom was not seated properly so it was cutting out, the chip I bought is a piggy back type, don’t think I care much for those the side clips don’t hold it place like stock. The oil pressure was just a bad sending unit. Runs like a champ again.

 

Code 42 - Its back, running just as before second cooling fan won’t turn on even with a/c on. The car can’t get out of its own way runs like crap!!! Stars right up runs for like 20 seconds and then the SES light comes on, if you put it in gear it doesn’t even want to more the car unless you really push it hard and then it will go done the road barely.
What are the other harness connections at the ecm for? Can’t find any were they would plug into?

 

Have you tried pulling the PROM and running? What does a code 42 indicate?

 

https://www.thirdgen.org/service-eng...ht-error-codes

This is a list of all of codes for our cars.

 

It turns out that the other connectors were from a performance programmer the previous owner installed, I removed them and repaired the wires and installed a new ecm, from OReilly’s, I have checked the continuity and ohm of the tan w black strip wire from the distributor to the ecm and it checked out ok. I sent the prom out and had it check and it was bad so they flashed it with the stock settings. When I installed everything it still ran bad but if I install the prom with performance piggy back it doesn’t give me the SES light, if I remove the piggy back and install the stock prom it runs the same and the SES light comes on (code 42). So I am thinking that the stock prom is the problem.
Also I have checked all the wires for the ecm and several of them show an ohm reading to ground not sure but that doesn’t seem right?
Any input is greatly appreciated.
Thanks
John

 

Well new ecm and prom, wires all repaired, ohm and continuity check on all wires, ignition module and coil checked out, still runs the same??????

HELP!!!!!!!!!!!!
John

 

I'm looking at the timeline for you posts. Is that right, the original problem was two years ago?

 

Yes, I could not find the problem then, it just started running right again, I thought it was the prom wasn’t seated properly. Then one day I got in it and it started all over again.
The only thing I haven’t replaced is the distributor itself.
I have tested the tan/black wire all the way from the coil wire to the distributor to the ecm and the grounds the ignition control module, coil, changed the ecm and prom twice, and nothing has changed????
John

 

im having same prob code 42 did u fix it

 

I retested the ignition module at Oriellys and it showed it was bad they also recomened that I change the coil as this was the second mod I replaced, so changed them both and now it runs great., So much so that we toke it to CO. on a 6 day trip 2,500 round trip no problems. (last summer)
John