Engine Miss dubbed ( the money pit )

rsm5773 · Jul 20, 2009

I bought a 1985 bronco for 195.00 in good shape body wise with a overheated 2.8. I decided to just buy another used engine and swap it in and do the duraspark conversion while i'm at it. I bought all new parts for the duraspark and wired it up per the instructions on the duraspark conversion on the tech library. Just so you know what i replaced distributor, coil, cap, rotor, wires, plugs, carb, module. These are all new parts.

The engine has a miss that is driving me crazy. Should the distributor black wire be grounded that runs from the distributor to the duraspark module? I have grounded engine to body, body to frame, engine block to chassis. could this be a ground gremlin?

I double checked to see if I have a tight valve because I set the valves and they were all good. I set the timing as good as i could with the idle being crappy.

The engine has a miss that sounds like the engine has a aftermarket cam but it doesnt. The miss is still present at higher rpms.

I followed the instructions per the conversion on this site. I'm at a loss the engine sounds great other than the miss. I have had 4 people listen to it and all sit back scatch there heads. Compression feels strong out the tail pipe, i will be pulling a compression test in the next couple days.

Any ideas would be great, thanks in advance.

Richard

rsm5773 · Jul 20, 2009

Think the dizzy could be off a tooth?

mwood1985 · Jul 20, 2009

lets see if we can narrow this down to a better diagnosis. AllanD chime in if i mess up something. keep in mind if its a junkyard motor the RBV is there for a reason. wrecked ones are usually a safe bet when getting used motors ect.

1. im assuming all plugs wires ect are good because of the duraspark conversion. check your wires and make sure one isnt burnt.

2. lets narrow the problem down to exactly which cylinders arent firing.
you can get a spark plug tester from advance autozone ect. follow its directions and it should light up on the good cylinders and not light up on the bad ones

3. id recommend testing all cylinders compression at this time with a compression tester. iirc you can use the loaner tool program at advance auto parts for free with a deposit . remove the plugs and instal the meter on the number 1 cylinder. turn the motor over by hand and read the guage. continue with the remaining cylinders. all cylinders should register within 10-15 psi of each other. given its a 2.8 id say they should be in the 160 psi area

just let us know what the results of those tests are and we shall see if TRS can figure it out

rsm5773 · Jul 20, 2009

The motor was from craigslist, the guy put a V8 in his ranger. I will do the tests tomorrow with the compression tester and the ignition tester.

Thank you guys so much :yahoo:

mwood1985 · Jul 20, 2009

anytime man thats what we are here for if you need anything else just pm me mwood1985

rsm5773 · Jul 21, 2009

This whole problem started at work 30 miles away from my tools. I made the decision last night to drive it home while running like crap, top speed was 25. I got 15 miles closer to home and the ignition lost spark. I believe that is one part of the miss that I had. Wonder if I wired the duraspark module wrong? it was straight forward and easy to understand. The bronco ran just not that well, wonder if I got a bad module from the beginning or my theory being off a tooth caused the ignition to go screwy.

Thanks Richard

Engine Miss dubbed ( the money pit )

rsm5773

15+ Year Member

rsm5773

15+ Year Member

mwood1985

15+ Year Member

rsm5773

15+ Year Member

mwood1985

15+ Year Member

rsm5773

15+ Year Member

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