I have removed the distributor several times. Need to know if there is a fairly definate way to confirm if chain has jumped a tooth or not. I am getting a rough idle, dies, lean condition, hesitation, eratic when cranking, and lacking power on an efi truck. Diagnostics keep comming back with lean condition and no serious codes. Fuel system and sensors have been checked, swapped with known good ones, or replaced. Coil, module, wires, map, hego, ect, fpr, plugs wires, cap, injectors, pickup coil, ecm, tank, pumps, filters, etc have been changed out. With the electrical distributor parts changed, truck ran better than new for two days. Next day all the same symptoms were back, soon as I tried to start it up again. EGR is not connected, no cats. In the past few years dealing with problem, it may be acting like flooding or burning too lean. Fuel pump is working and correct pressure ad compared to another truck. Motor is all original with 95k miles. 89 5.0 MPI in Bronco. Any ideas would be greatly appreciated. I now know how its supposed to run and hope it will do that again. Can conditions exist for the timting chain to jump back and forth from correct setting to off a tooth? I get a timing flucuation of +4 degrees on No 1 plug and -4 degrees on No 2. Is the cam timing gear on standard trucks still plastic or do all later model efis come with roller chains? This has been an ongoing problem since I bought this vehicle 5 years ago in non running condition. It has always run doggish and then got bad one day. Then last week after swapping the new parts is was perfect and ran better than my 94 Bronco for two days. Then something went south and then problem. This isnt a reoccuring problem. Its been bad to not drivable, then perfect for two days, and back to same or like problems.

 

might as well change the brain....or have you tried that?

 

Turn it to TDC and see where distributor is pointing. The only other way I can figure is to remove the timing chain cover and see if the dots on the cam and crank align.

 

With older engines (with straight up camshafts - not retarded nor advanced) we used to check by turning the engine to TDC on the end of the no. 1 cylinder exhaust stroke. The exhaust valve would just be closing while the intake valve would just be opening (this is the "overlap"). So when the exhaust and intake rockers were open the same amount, the piston was at TDC if the camshaft timing was right.

But I don't know if this will work on your particular engine.

 

verify if it has enough slack to jump time..watch the rotor as you turn it over back and forth with a braker bar and a 15/16 socket on the crank bolt. Get the balancer somewhere near the timing marks so you can use them as a guide to measure.....

turn it one way until it starts to move the rotor..note where the timing marks are on the balancer (bring them up to the end of the marks)...now turn it very slowly the other way until it just starts to turn the rotor..note where the timing marks are. Not sure how much slack is exceptable.....but the tighter the better......