OK, on my 91 305 tpi I am getting my SES light on and the code I am getting is code 43 which is the code for ESC. When it comes on the car starts running like crap. It won't die on me but the car becomnes unresponsive, accelerating slowly and stuff like that.
Also this is intermitten, sometimes it will run fine and other times it won't. According to what the manuals say etc this must be due to the fact that the ecm is retarding the timing because it is detecting knocking. Is this similar to detonation or the same thing?. When this happens the engine runs rough but it doesn't seem to be knocking or detonating, I mean the engine does not shake or stuff like that. Anyway, if it is not detonating what else could it be?. I cheked connections and all seems to be O K. Could the ESC module be faulty or the knock sensor?. Since it is an intermittent problem, sometimes switching back and forth in a few minutes I would assume that the sensors are O K. I read somewhere that loose grounds could cause some trouble. My engine ground broke some time ago and I bought one at autozone. The new one is a really big and wide one compared to the original. Since I was on the road when I installed it I think I did not screw the bolt as tight as I could since its location is a little hard to reach. Anyways, could a loose engine ground be causing this?. Also two months ago I installed bosch platinum four prong spark plugs?. Are these good?. Could they be causing knocking?. Some mechanics think they are a peace of crap and others swear by them. Could this be the cause?. Any help will be greatly appreciated, thanks!.

 

I usually swear AT them. Bosch plugs are great in euro cars....never again in my American iron.

Yes, the engine ground could be causing your problem and other problems as well. You should have 2 grounds on the engine, at the back of each cylinder head.