350 TPI motor. The car was mising and i tuned it up. When i am at idle, the rpm's r jumping around like it is missing but it is no miss. Smooth when i am driving but as soon as you stop the rpm jump from like 500 to 700 back and forth. It almost feels like the car is loading up like big blocks do. It is throwing no codes whatsoever. Strange though i can drive it normal for a few miles and it is ok, but as soon as i nail first gear then it starts whith the jumping rpms at idle. I am thinking dirt in the injectors or on the sock in the tank? last time i checked fuel pressure it was 40 psi. Any help would be appreciated.

 

If I understand your post, I probably had a different problem, but then again maybe not.

On my 305/tpi, the tach needle would sometimes jump, but only at idle speeds, no codes, etc. The engine speed also remained constant as determined by ear. Only the tach needle would jump every now and then at idle. The problem started suddenly and then gradually occured more often.

The problem in my case was a spark plug wire that became "open" (infinite resistance). The center conductor (carbon) had broken, so it could not pass voltage consistantly.

Replacing the wires cured the problem.

FYI, I found the bad wire by just doing a simple resistance check on the secondary wires.

Did you replace the spark plug wires? If so, are all the connectors on good?

[This message has been edited by Stuart Moss (edited August 06, 2001).]

 

I just put brand new wires and plugs plus a cap and rotor.