Running issues

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Oct 2, 2022 | 05:30 PM

Jkonks

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Trailering

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Running issues

Hi all I have a 01 f250 5.4l that I recently changed the driver's side head gasket on and now It runs like crap and has low power, the stft is high on both banks witch made me think vacuum leak and after looking everywhere and doing the starting fluid method I came up empty handed
my question is if the timing chain was off one tooth on the one head would that cause the problem I'm having?

Oct 3, 2022 | 08:21 PM

99f350sd

Lead Driver

Joined: May 2003

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From: Lyndonville, Vermont

I suppose it would run like crap. Have you checked the coil wires make sure you don't have them backwards on the wrong cyl...prob hard to do...take a compression test on that bank.

Oct 3, 2022 | 09:26 PM

Jkonks

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Quote:

Originally Posted by 99f350sd

I suppose it would run like crap. Have you checked the coil wires make sure you don't have them backwards on the wrong cyl...prob hard to do...take a compression test on that bank.

Yeah can't really get wires mixed up, I did compression check on the head I had off to make sure I got compression back after I changed gasket cylinder 6,7 only had 20 psi before I started!

Oct 4, 2022 | 09:41 AM

Djosbun

Fleet Mechanic

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From: Southwest Ohio

A vacuum leak would lead to a lean running condition (negative fuel trim readings). Use a bore scope to see if any pistons are wet due to injector bleed-down.

— Dave

Oct 4, 2022 | 09:51 AM

Jkonks

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Quote:

Originally Posted by Djosbun

A vacuum leak would lead to a lean running condition (negative fuel trim readings). Use a bore scope to see if any pistons are wet due to injector bleed-down.

— Dave

Wouldn't checking fuel rail pressure tell me the same thing?

Oct 4, 2022 | 12:51 PM

Djosbun

Fleet Mechanic

Joined: Oct 2017

Posts: 1,704

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From: Southwest Ohio

You’ll need to perform an injector buzz test to locate a bleed-down issue. Can also pinch off the PVC hose to see if the STFT’s come back up to zero (which will guide you down another path).

— Dave