tooleyondeck
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I'm gonna beat Joe to it and say this qualifies as SAGE ADVICE lol
SOLVED!!! '96 Yukon Cylinder 5 Misfire
- Thread starter XBT7
- Start date
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Everyone wants to buy parts, I'm old school and cheap. Do some diagnosing first, can't believe a shop just says injectors going by common failure without proof. You had the plugs out, good time for a compression test. Before wire replacement unless I saw something obvious it costs nothing to do a poor man's scope test. A spray bottle of water, get high tech and put a little dish soap in so it clings. Have someone power brake the truck a little and spray a mist at each wire start at the plug. A good spark tester that is adjustable will test the coil to see just how good the spark is. If I read correctly it looks like all of the misfires are on the drivers side bank also, did they check fuel pressure and the regulator?
A cheap android scanner on live data will help a great deal. I agree- throwing parts at it is not the answer. Common failures in Ignition are in this relative order for me-
Distributor cap/rotor Delco/Denso/United DCR820x only. Plug wires. Spark plugs(NGK very good and inexpensive). Coil. Ignition moduleDelco/Delphi. Distributor(united a good choice).
Watch fuel trims and misfires on live data while Driving steady state at various rpms. A fuel pressure gage with long hose under wiper blade and a spark tester at coil, coil wire, and individual terminals on cap rounds out most testing at under$100.
Good luck.
Distributor cap/rotor Delco/Denso/United DCR820x only. Plug wires. Spark plugs(NGK very good and inexpensive). Coil. Ignition moduleDelco/Delphi. Distributor(united a good choice).
Watch fuel trims and misfires on live data while Driving steady state at various rpms. A fuel pressure gage with long hose under wiper blade and a spark tester at coil, coil wire, and individual terminals on cap rounds out most testing at under$100.
Good luck.
Got it. I will check that tomorrow after work and will report back here. Hopefully once I'm done this won't be the 350 of Theseus.
When we had the plugs out at the shop we did a compression test and it was great between cylinder 1, 3, and 5. I bought a spark tester and tested the plugs on cylinders 3 and 5 and both were flashing erratically. This weekend I will borrow a timing gun from my uncle to see if there is an issue with timing.
These engines REQUIRE a scanner to set timing. Spec is 0deg +-2 at !000-1200rpm. Name of timing something like cam/crank correlation depending on which scanner. If you loosen distributor you must reset timing or code sets.
This might help.- https://www.gmt400.com/threads/88-95-service-manuals.43575/
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Timing "gun" or timing light isn't used on a Vortec engine, need a scan tool that can tell you the readding. A flashing spark tester isn't testing the power of the coil, just that an electrical impulse occurs. What compression numbers are "great"?, how does great compare to the other 5 cylinders?
SOLVED!!! Thank you to user Hoesgottaeat2 for providing me with the exact information I needed to fix my problem. Thank you to everyone else who helped me with this problem, you are very much appreciated! It was in fact my distributor gear that had worn down and caused my timing/rough idle issue. It just so happened to be cheaper and faster to replace the whole distributor than it was to just buy the gear haha.
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Hoesgottaeat2
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