backfiring replacement engine

drivestoofast

Registered User
hi i am a new member and am seeking help...I broused thru the forum but didn't see a specific answer....
I swapped an ailing engine out of a newly purchased sc..and used most of my old electronics as they looked like they were in better health...The replacement engine has only the orginal cam sensor on it..the DIS, Coil, and Crank sensor are all from the original engine...The engine turns and fires , but misses horribly..it can be coaxed up to a high idle but misses throughout the range....Is the crank sensor possibly the problem?



I have a white mint 89sc and recently bought an anniversary sc..
One for when I am in a good mood and one for when I am in a "Black " mood....
 
If you switched 1&3 plug wires at the coil pack it will miss on 1 cyl only. You could have installed the cam sensor wrong. Check your plug wires first.

Jeff
 
still no luck with the engine swap..checked everything 4 times..even swapped the cam sensor and set it up...still backfiring like crazy.
 
Make sure you clarify if it is backfiring (exhausting through the intake or combusting out the exhaust) and not simply missing.

Big difference. Backfiring is almost certainly a timing problem. That's because the engine is firing the cylinder when one of the valves is not fully closed, thus a "backfire". It is also often quite violent.
 
well how does this sound?...It is trying to push the air filter thru the bumper and the pistons thu the oil pan...sound violent enough?...
 
If you used the Haynes manual to determine the spark plug wire location on the coil pack....it's wrong.

The correct sequence on the coil pack when viewed from the front bumper is:

123
564

not

123
456

As shown in the manual. Switch the wires and it sould run much better.

{edit} Here is a picture I borrowed from Lance Morgan that explains what I'm talking about.

PlugandWireLayout.gif


David
 
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