I have a 1994 Cadillac ETC (Northstar) and just recently had one of the ignition modules replaced because it was missing terribly. It started missing again shortly after having the module replaced and I noticed it idled rough with high (1000-1100 rpm’s) at cold start. Sometimes when accelerating it would miss and hesitate as well. The other day, I pulled up to a stop light and it just quit. I restarted it and it was running extremely rough, then clouds of smoke poured out from the front, back and under the car. The darn thing leaks oil like a sieve so sometimes it will smoke from the engine compartment but this was much worse. I limped it home and it was obvious that there was an extreme power loss almost like the transmission was slipping. As I drove, the smoke became much less and it didn’t seem as though it was coming from the exhaust. When I got home, I checked the transmission fluid and it was okay. I shut the engine off and checked the oil and it was okay. Then I looked under the car and the catalytic converter was glowing red hot! I just got done swapping out each ignition module with a new one and starting it after each move and it’s still the same.
Any suggestions? I thought it might be the timing chain had slipped but I thought I read that these are unable to slip…
Thanks for any help,
John
When a cylinder misfires, the fuel charge that was in the cylinder gets pushed to the catalytic converter. A lot of cylinder misfiring means a lot of fuel going to the catalytic converter and burning. As you saw, this burning can heat the cat to red-hot. The high heat can ruin a catalytic converter.
You need a pro to find out why the engine is misfiring. And, you may have to replace the catalytic converter.
Those symptoms on an 85 Cadillac would lead me to believe that the engine control computer was in bad shape. On your car, I would say to find out if there ar any useful codes to get you started. Go have it scanned. Lots of car parts places will do it for free.
The auto parts houses WON’T do a scan on a 1994 model. There is a technique, using the ignition and observing the flashes of the check engine light, in your repair manual, to determine trouble codes.
The erratic rpm may be caused by a vacuum leak. With the engine idling, pull each vacuum hose and plug each vacuum port , particularly the one for the brake booster. If you note a change in idle, the component the vacuum hose services may be losing vacuum.