Very rough running after replacing HG's!???

zom91

Registered User
I finally got my engine back together a couple of days ago and fired it up. It runs O.K. for about half a minute and then when the idle comes down, it starts getting worse up to the point where it will barely idle. I was told that it might be the O2 sensors because they might have been damaged by coolant going down the exhaust, but I'm not sure. It ran great before the HG's blew last fall, no check engine lights or anything. It did sit all winter in an unheated garage, but a sensor wouldn't just go bad from sitting would it? Any help is greatly appreciated.

Thanks,
Doug
 
Vacuum leaks

What does your bosst/vac gauge tell ya when it is idling fine? then as it drops off?

The most common problem people have when putting the motor back together is vacuum leaks. Take a can of carb cleaner, or electronuics contract cleaner and spray all you IC joints when the car is idleing, if the car changes idle while spraying a location you have a leak.

If the gaskets blew bad enough then there is the possibility that the O2 sensors were indeed damaged, if the engine is throwing a CE light when it ides pull the codes and go from there . . .

Dave
 
the 2nd most common problem when putting the engine back together is getting the plug wires on wrong. If you followed an older Haynes manual, then it is wrong. If you got the 4-5-6 cyl spark plug wires on wrong, then it will start, and kinda idle, but once you touch the gas it will backfire and/or just die. Make sure your coil pack -vs- engine wire layout looks like this.

Engine
3 - 6
2 - 5
1 - 4

coil pack
1 - 2 - 3
5 - 6 - 4
 
Thanks for the help!

I ended up having the number five and six cylinder wires reversed on the coil pack! Runs great now. Thanks for the help guys, I really appreciate it.

Doug
 
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