Help!! Mysterious miss.

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Nov 14, 2003 | 08:46 AM

meck1

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Help!! Mysterious miss.

Mine is an '87 F250 with fuel injection. If I start it up without touching the gas and just let it sit and idle until warm, it will run perfectly. If I even touch the gas once, it immediately starts missing badly and continues doing so until it is warmed up when it, again, runs perfectly.

Does anybody have a clue what is going on here?

Thanks

Nov 14, 2003 | 10:38 AM

sicbpguy

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Have you tried to pull any codes? That may indicate a problem with some EFI components at different temperatures.

Nov 16, 2003 | 02:46 PM

paulfix

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Try using a hair dryer to warm up the TPS prior to starting and during warm up and see if you can get it to misfire with this EFI sensor warmed up 1st

Nov 16, 2003 | 03:54 PM

rhetor

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From: redding U.S.A.

it sounds like you have a dead spot on the TPS sensor at idle, and when you tap the throttle it gets a bad signal, and just goes nuts.

the hair dryer idea was a very good one!

Nov 18, 2003 | 02:07 PM

meck1

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Thanks for the advice. This miss is not an earth-shaking problem, but it just bugs the devil out of me when something doesn't run right. I'll try what you have suggested as soon as the weather permits. I work on the truck outside, and right now we seem to be into some kind of monsoon season that refuses to let up. I'll let you know what happens.

Thanks

Nov 23, 2003 | 04:39 PM

meck1

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Okay, with the weather's cooperation I was able to get a little work done. I pulled the computer codes and got one only, a #32, an EGR fault code. The EGR seems to be moving fine, and the EVP checks out. I'm not sure where to go on this or how it can be causing the weird idling miss that I'm getting.

I also heated up the TPS with a hair dryer as you suggested. It made no difference in the problem.

Does anyone have anymore hints or suggestions as to what I can check?

Thanks

Nov 24, 2003 | 10:13 AM

sicbpguy

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I'm sure how the EGR would cause a miss. It can cause a rough idle, but that does not sound like your problem. Make sure you check the EGR vacuum regulator on the side of the valve cover ( trace the vacuum lines back) and check the vacuum lines to make sure the vaccum is getting to the EGR to make it work.