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87' f150 4speed 302
It has had a popping, backfiring problem since I first seen the truck 6 years ago. I bought it 2 years ago and have been trying to find the problem. It pops when accelarating, especially when in a low rpm situation. It was my daily driver until 5 months ago so now I can dig a little deeper into it. The other day it was runnign a little rougher than usual so I checked it the timing, which has been checked by several mechanics in the past. And I could spin the distributor by hand. Timing marks are confusing on this thing but somone has yellow paint on the M balancer. I couldnt get the timing close for lack of space for module to swing around. I noted that the plug wires are off by one hole according to the Haynes manual. So I re-plug the cap, have someone turn the key while I spin the distributor until it starts. I can barely get the mark on the balancer lined up with the pointer but its not running right. Is there a chance that someone has the distributor stabbed a little off and has compensated for it by moving the wires around? If so, is that just as good?
Thanks, sorry for the long post.
Ignition timing is just as good, but for fuel injection I think it could be messing things up. The distributor is probably off a tooth or two. I'd pull it out and make sure the rotor points to the 1 on the cap. The computer gets a signal when the engine hits TDC on cylinder 1 so it knows what fuel injectors to fire, and if fires the injectors at the wrong time, it will run bad. I would also double check the mark on the balancer to make sure it is in the right relationship with TDC of cylinder number 1 (make sure the outer part of the balancer hasn't turned on inside part.