Code 41 Code 42 New Motor New Ignition New Chip
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
Code 41 Code 42 New Motor New Ignition New Chip
Hello,
I have just completed restoring a 1990 that had had an engine fire. The car came out great. Installed a new wiring harness, and had the engine rebuilt by a performance shop. Installed new injectors and sent out for a mail order tune seeing as how there aren't really any OBD1 tuners out there anymore. Got the first chip back and the car wouldn't start. After messing with the distributor I got it running, sort of, but it was back firing and running really rough. Spent about a month changing plugs, wires, checking compression, fuel pressure, and reinstalled the distributor so many times my head is spinning. Called the tuner and he was kind enough to send out another chip under the pretense that it could have been bad. And I believe it might have. Got the car running, and it idles ok. But it still back fires under certain conditions, idle surges like I have a huge cam and it generally runs like crap. I have a check engine light so I pulled codes. Coming back with Code 41: Ignition Control Error or MemCal Error or Internal ECM fault & Code 42: A PROM not fully seated in the ECM can result in a Code 42 or EST line open or grounded. I'm not sure what to think or where to begin to diagnose this. Part of the problem is both of these codes represent two completely different issues. My distributor is new; it is a camaro small top distributor with a msd external coil, and of course there is the aftermarket prom chip installed.
Ideally I wish there was a reputable shop in my area I could just drop this thing off at and get it buttoned up.
DG
I have just completed restoring a 1990 that had had an engine fire. The car came out great. Installed a new wiring harness, and had the engine rebuilt by a performance shop. Installed new injectors and sent out for a mail order tune seeing as how there aren't really any OBD1 tuners out there anymore. Got the first chip back and the car wouldn't start. After messing with the distributor I got it running, sort of, but it was back firing and running really rough. Spent about a month changing plugs, wires, checking compression, fuel pressure, and reinstalled the distributor so many times my head is spinning. Called the tuner and he was kind enough to send out another chip under the pretense that it could have been bad. And I believe it might have. Got the car running, and it idles ok. But it still back fires under certain conditions, idle surges like I have a huge cam and it generally runs like crap. I have a check engine light so I pulled codes. Coming back with Code 41: Ignition Control Error or MemCal Error or Internal ECM fault & Code 42: A PROM not fully seated in the ECM can result in a Code 42 or EST line open or grounded. I'm not sure what to think or where to begin to diagnose this. Part of the problem is both of these codes represent two completely different issues. My distributor is new; it is a camaro small top distributor with a msd external coil, and of course there is the aftermarket prom chip installed.
Ideally I wish there was a reputable shop in my area I could just drop this thing off at and get it buttoned up.
DG
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
Man, I'm in the same boat as you currently. I'm getting the c41 after doing a chip alteration. I ended up going back to my original file(that checks out okay in tunerpro) but it still is there. I'm still trying to figure things out and will be working on it a bit this week.
One thing that I noticed to check when your car surges like you're talking about is the idle air control. I'd just make sure that it's in the operating range. My car was doing that after a bolt on the throttle body adjustment screw came off. It was maxed out at 160 90% of the time and the car wasn't getting enough air.
However, I'm not much help on the c41 though....
One thing that I noticed to check when your car surges like you're talking about is the idle air control. I'd just make sure that it's in the operating range. My car was doing that after a bolt on the throttle body adjustment screw came off. It was maxed out at 160 90% of the time and the car wasn't getting enough air.
However, I'm not much help on the c41 though....
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
[QUOTE=Danspeed1;1590291685I have a check engine light so I pulled codes. Coming back with Code 41: Ignition Control Error or MemCal Error or Internal ECM fault & Code 42: A PROM not fully seated in the ECM can result in a Code 42 or EST line open or grounded. I'm not sure what to think or where to begin to diagnose this.[/QUOTE]
The first thing you should do is look at this list:
https://www.corvetteforum.com/forums...post1576116036
and pick out the CORRECT problem for your year. This X or Y or Z thing is not helpful.
You usually get an error code 42 when you disconnect the EST connector to set the timing.
The first thing you should do is look at this list:
https://www.corvetteforum.com/forums...post1576116036
and pick out the CORRECT problem for your year. This X or Y or Z thing is not helpful.
You usually get an error code 42 when you disconnect the EST connector to set the timing.
