Another rough idle ?????

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Nov 18, 2006 | 08:08 PM

mechmagcn

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From: Moro Bay, AR

Another rough idle ?????

I recently purchased a 94 F250 IDI with 165K on the clock. When it is first started, it has a dead miss at idle(and sometimes has a fuel knock like a stuck injector). Bring the RPMs over 1K and it smooths out, but when it returns to idle, it gradually starts missing again until it's a dead miss. After it warms up, sometimes it misses at idle and sometimes not. I am running a double dose of DK in it now. If this doesn't help it, I will pull the injectors next. Looks like it has a recent pump replacement and 4 new injectors. Any more ideas?
Jeff

Nov 18, 2006 | 08:49 PM

PLC7.3

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From: Manitoba

4 old and 4 new injectors that is a witches brew......and most likely you have 4 firing at the correct time and 4 of by a hair.

Nov 18, 2006 | 09:14 PM

Dave Sponaugle

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From: Nutter Fort, WV

And one of them needs replaced right now, because it sounds like it is not spraying correctly.

Nov 19, 2006 | 07:49 AM

mechmagcn

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From: Moro Bay, AR

Quote:

Originally Posted by PLC7.3

4 old and 4 new injectors that is a witches brew......and most likely you have 4 firing at the correct time and 4 of by a hair.

I wasn't too happy when I saw the gray paint on 4 and no paint on the others. Don't know if they were tested and set or just left behind. This is an old city street dept. truck and seems to have been well kept. For the price I gave, I can afford to do a few repairs.
Jeff

Nov 19, 2006 | 08:25 AM

PLC7.3

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From: Manitoba

You may want to do a compression test before tearing it appart, your mileage is about where the valve guides wear on the 7.3 and they could be part of the problem too.

Nov 19, 2006 | 08:30 AM

mechmagcn

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From: Moro Bay, AR

Quote:

Originally Posted by PLC7.3

You may want to do a compression test before tearing it appart, your mileage is about where the valve guides wear on the 7.3 and they could be part of the problem too.

I've had several with severe valve guide wear and this one sometimes has the telltale chuffing from the tailpipe. The only ones I've seen it on before were 89-91 models though.
Jeff

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