1997 5.4 Expedition bad misfire...HELP PLEASE!!

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Kermit

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Timing chain
Just curious Chris, but why do you think timing chain? Because of the marble noise or the codes? Honestly curious here, not trying to be an ass or anything, just wanna pick ur brain.

For the op...I had a similar issue with my 99 expy... sputtering, loss of power, engine was "loping" (personally I call it surging, the p.o.s mechanic called it loping) etc, threw the 1401 code and 2 codes for upstream o2 sensors, and a code for misfire on cyl 4. The p.o.s mechanic tried convincing me it was intake gasket (personally I think he was after the $700 gasket job but really knew it was pcv line). After replacing the 02s and the egr valve (needed done anyway, it was cheap and they were original parts with 230k on them) turned out to be a vacuum issue. Replaced the pcv line and voila, ran like a champ. So the p.o.s mechanic was right on 1 point, it was a vacuum issue but no where near as bad as the intake gasket.
 
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ChrisOIFdoc

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Just curious Chris, but why do you think timing chain? Because of the marble noise or the codes? Honestly curious here, not trying to be an ass or anything, just wanna pick ur brain.

For the op...I had a similar issue with my 99 expy... sputtering, loss of power, engine was "loping" (personally I call it surging, the p.o.s mechanic called it loping) etc, threw the 1401 code and 2 codes for upstream o2 sensors, and a code for misfire on cyl 4. The p.o.s mechanic tried convincing me it was intake gasket (personally I think he was after the $700 gasket job but really knew it was pcv line). After replacing the 02s and the egr valve (needed done anyway, it was cheap and they were original parts with 230k on them) turned out to be a vacuum issue. Replaced the pcv line and voila, ran like a champ. So the p.o.s mechanic was right on 1 point, it was a vacuum issue but no where near as bad as the intake gasket.

Timing chain was my quick response, but anything related to the timing was my suggestion because of the misfires in combo with the marble sound. Seems to me like it jumped time. Hopefully the guy will respond to the thread and let us know what he found.
 

Kermit

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How does the marble sounds relate to timing Chris?
 

ChrisOIFdoc

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Pre-ignition during the compression stroke, loose chain hitting the cover, valves rattling, etc.. all with misfires.

If you have an older vehicle with a distributor...get your crows foot...loosen it...start turning it out of time and you will hear what I'm talking about.
 

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