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Physician heal thyself

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Jan 3, 2012, 1:01 PM

Post #1 of 6 (2102 views)
post icon Physician heal thyself Sign In

Odd subject title but background on me. Disabled ASE Master and I can't remember the last time I had this much trouble.

I'm at wits end with this one. My own 2004 GMC 1500, 4.3L auto 2wd exended cab. 165k. Complete tune up in August with Borg Warner parts. Approx. 2 months ago started getting check engine light with P0300. Only code ever. Would feel the miss at around 65-70 for maybe 2-3 seconds and run fine after that. Might occur 2-3 time in 10 miles and might not. I checked the cap/rotor and found arcing so cap/rotor replaced. Worked perfect for about 2 wks and started again. Checked with friend who owns a shop and Alldata showed crank sensor may be the cause. Replaced with no solution. Thinking a high explosive might help tremendously!!Wink Thanks in advance.

(This post was edited by Pokerface77 on Jan 3, 2012, 3:29 PM)

Ultimate Carjunky / Moderator
Discretesignals profile image

Jan 3, 2012, 1:31 PM

Post #2 of 6 (2087 views)
Re: Physician heal thyself Sign In

Does your friend that owns the shop have an enhanced scan tool to look at the cylinder misfire history to determine which cylinders are misfiring?

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Jan 18, 2012, 12:15 AM

Post #3 of 6 (2021 views)
Re: Physician heal thyself Sign In

Update to this problem. Howard scanned history misfires. Cyl 4 90k occurances, cyl 3 few thousand. Cam retard 22 degrees. Tech did crank relearn but no fix as yet.

With the arrangment of the cap contacts this would make sence to me if the distributor is worn and shaft rising in the housing or that the timing chain has some play in it. My next step is to remove the cap and see how much slack may be in the timing chain.
Any ideas or advice? Thanks, Tim

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 19, 2012, 11:54 AM

Post #4 of 6 (2007 views)
Re: Physician heal thyself Sign In

OK - saw arching once at dist cap and replaced it. Shaft wear at 165K is a maybe to check and may have caused a problem? You said a new on fixed it for a while so I'd be checking that out again.

Is this engine sludgy at all?

Timing chain lash? You can check that with dist cap off, turn crank bolt and see how far it turns before rotor turns as a clue. Shouldn't turn much - say 5-6 degrees is too much for my liking. Not sure if the dumped using nylon cam gears that even with real care oil changing still can wear out and jump around but with more regularity.

If you mist cap, wires can you make it/them arc visually or cause a skip?

Just some ideas to check,



Jul 19, 2012, 1:55 PM

Post #5 of 6 (1672 views)
Re: Physician heal thyself Sign In

Sorry for such a late reply/repair but here goes. Finally took truck to the shop, ask for the timing chain to be replace because of a slight difference between the crank and distributor. After this, no change. OK, my bad but lets figure this thing out...The mechanic(?) spends a day checking it out, says it needs fuel injectors, (can't replace just one on this model. Idles fine, down the road great. Check engine comes back on going home with the same code. He tells me "drive it a couple days, lets see if it learns itself."

Three days later and about 200 miles, accellerating up a slight hill, it just pops!!! and dies. Tow it back, just a little upset at this point, just spent $800 (I know $300 is my goof up). Half of the gears on the distributor are GONE.

I was friendly with the owner as he was a competator yrs ago. Will replace the dist if I'll go get it. No problems for 5 months. Now I'm still wondering if something could be wrong with the cam because of the wear on the dist gear. Any thoughts??

Thanks, Tim

Veteran / Moderator
nickwarner profile image

Jul 19, 2012, 3:12 PM

Post #6 of 6 (1664 views)
Re: Physician heal thyself Sign In

The cam gear is hardened steel. I believe (someone will surely point it out if I'm wrong) that the distributor gear is bronze. The soft metal gives first without damaging the more expensive cam, a sacrificial lamb if you will. Thanks for posting the fix.

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