Hi, I have an 88 IROC w/ 350 TPI. I was having hte problem of the car hestitating and stumbling after a bit of running and then the SES comes on w/ a consistant code 42. I had tested the ignition module it tested okay it was at a local autozone. Then i cleaned the connectors to and it seemed to disappear for a week or so. Now it is back with a vengence. When its bogging i get popping in the exhaust, which i think is fuel, so I think its misfiring. I want to blame the ignition module and just replace the thing. What do you think? thanks!

- Tom

 

D-X,

Don't overlook the HEI primary wiring, and test the pickup coil in the base of the distributor.

 

Will do.. how can I test the pickup coil ? Are there places that do it? thanks!

 

Disconnect the pickup coil leads from the HEI module. Connect an ohmmeter and read the resistance. It should be betweem 500-1,500 ohms. Check each lead to ground on the highest resistance scale, and there should be NO indication (infinite resistance). Failure of either of these indicates a problem with the pickup coil.

 

Oh NO! I'm such a moron! I accidentally left the paperclip in the ALDL and started the car! It ran but it was hesitant as always so I took out the paper clip while it was running and turned the car off. Then It wouldnt start again!!! Do you think I fried the computer??? OIY!

 

does the SES light come on when you turnthe key onto the ON position? Well, I guess it could still be fried even if the SES light did come on, my computer was, and the SES light came on. I dunno dood....

 

My car constantly throws a 42 due to a loose connection into the ECM. I think I'm ready to replace the ECM, but when it throws the code I wiggle the connector and reset the codes and its good to go for about another month or two.....

Try it-especially if you have an aftermarket PROM and the harnesses have been unplugged a few times.

Another possibility is that the coil may be coming loose from the coil bracket. I have had it throw a 42 from that also.

 

I wiggled the hell out of the ECM while it was doing it and I it didnt seem to help but I'll check out the coil. But right now im not sure what to do because now it wont start after i messed up with the ALDL .. grr. Thanks!

- Tom

 

I hooked up a scanner to my ALDL and it couldn't read, said there was no information being given. My SES light doesn't come on either...could my ECM being going south?

 

check the ECM fuse near the battery... if your lucky, that protected the ECM and blew.

 

I'll check that out, but if that fuse blew wouldn't something else have gone wrong with that?

 

I just replaced my ECM because of th code 42. I went through and replaced the module and the a couple of wires from the harness and it was still there. Replaced the ECM and it went away.

 

The fuse protects the ECM. Hey, its worth a try. I also had to replace my ECM due to a TPS low voltage problem. It is 250bux canadian for a brand new one.

 

I paid $79.99 at Autozone.

 

Nice... is it AC-Delco?