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Old 07-23-2009, 07:11 PM
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Engine skip

Well, it was running like a swiss watch, like a brand new engine. Then on Monday, it started running kinda rough.

It'll start, but seems to idle a little rough, not much. When moving, it kinda jerks like it's misfiring, but it will not stall out.

Pulled every plug, changed every plug, no different. Checked all the wires, cap and rotor. Checked, double checked each vacuum line and the vacuum advance. Changed the fuel and pvc filters, Gumout in the gas, even tried dri-gas. EGR is new, 2k miles, checked all the fluids and air filter and breather filter.

Anyways, you guys have always come thru for me in the past - any ideas what I might be missing?

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Old 07-23-2009, 09:35 PM   #2
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Have you checked the Crankshaft position sensor? It is located on the front of the tranny and has wires running from it to the throttle body. Quick fix and only costs about $40. It has something to do with the timing as the crank turns. Also check your wires into the rotor from the main wiring harness. Once mine had a short and caused something like you are describing. Good luck...I know how frustrating it can be, but you figure it out.

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Old 07-23-2009, 10:51 PM   #3
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4.2?
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Old 07-24-2009, 05:13 AM   #4
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Catalytic converter may be breaking up, a chunk of the core may be partially blocking the exhaust.

Have someone rev it up in neutral with their foot on the brake. Stand behind the jepp & listen to see if the exhaust sounds different.

EGR (even though it's new) could still be it. Try plugging it's vacuum line, to see if it changes anything.
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Old 07-24-2009, 06:37 PM
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Thanks for the advice. I thought about the EGR, did block the vac line and no different.

Didn't even think it might be the cat. Looks like this weekends job may involve a dirty nasty exhaust. Put a new muffler and tailpipe on it about 2 months ago to get it past the inspectors, so this may be the right call.
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Old 07-27-2009, 07:02 PM
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DUMB ASS OF THE WEEK AWARD

Did you know that one end of the ignition coil wire is straight and the other end has a 90 degree bend?

Did you know the straight end is copper and the bent end is steel? The distributor cap has steel contacts? The coil copper?

Did you know that it'll run even if the wrong end is pushed in kinda close to the contact in the coil so it sort of arcs? Even though it's not actually touching?

I do now.

Amazing how good it runs when the effin thing is plugged in correctly.

At least I won't need a new exhaust, seeing how I changed it over the weekend. Also, I am real familiar with the vacuum system on the 4.2 now, maybe even a pro! Don't have a single vacuum line on her now more than 48 hours old! Me and the entire electrical system are really good friends also.

Never even HEARD of a crankshaft position sensor, but by all that is holy, I sure as s#*t know all about it now.

Yes, my fastidious fellow forumers, I am a dumbass. Thanks for the advice though! I hope this helps some poor sap somewhere down the time corridor.

Bobby the Bonehead


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