ok iam having problems with my 91 305 tbi. the motor was just rebuilt all stock. it will start up and idle fine with the est wire disconnected, but once i plug it in it pops alot rpms every where barely stays at idle and when i put the timeing light on it the mark is bounceing aroung on the timeing flag. then just dies. all the sensor have been replace except for the knockand the ones on the throttle body. any ideas??

 

I had an issue like this once and it turned out to be a bad ECM.

 

yea i have been thinking about that, but would it really just stop working like that??

 

When I got my car it had that exact problem. After checking everything I tried the ECM and its worked ever since.

 

as weird as this may sound ive seen bad pickup coils in dist cause same issue signals too weak to run on est but fine running off base timing in module.also since you just put motor in make sure ALL ground are hooked up and tight.

 

i replaced the pick up coil and checked the ground all are good, guess ill try the ecm next

 

replaced the ecm and it still doesnt work WTF!!

 

if my timing chain was like a tooth off could it do this?? no mater how long it runs it still wont pop a service engine light