99 7.3 cold surging

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Nov 18, 2010 | 08:23 AM

meporsche

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99 7.3 cold surging

I've only had the truck for a few weeks, 193K on it. 99 F250SD. WHen I drove it yesterday (temps in mid 30s) it was surging for about the first 15 miles, then it flattened out and ran fine. This happened twice. A little better if I goosed the throttle but still there. This is the first time I have sriven the vehicle in lower temps.

I'm thinking the fuel filter is partly plugged and the thicker vis fuel is not flowing well enough to injectors/pump? Or is there a fuel heater on this that has failed? Combination?

Any help appreciated. I'm going to change the fuel filter today anyhow but have a nagging suspicion it isn't going to correct the problem.

Thanks,
Darwin

Nov 18, 2010 | 08:32 AM

clux

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From: Carhenge

Sounds like it's just your EBPV kicking in and out to me.

Nov 18, 2010 | 08:41 AM

CampSpringsJohn

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The Exhaust Back Pressure Valve makes a funny hissing sound when it's working. If this sound co-insides with the surging you are experiencing, it is normal. The EBPV is activated when temps are below something like 40 degrees, or maybe it's 30, I don't remember. But it works until the engine oil temp reaches something like 100 or 120 degrees.

Nov 18, 2010 | 08:43 AM

CampSpringsJohn

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You mentioned the fuel, that is also a possibility. Diesel fuel can get cloudy at temps in the 30's. The crystals can plug the fuel filter. The fuel filter housing does have a heater in it.

Nov 18, 2010 | 12:31 PM

meporsche

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I corss posted on the SD forum. A couple of replies dealt with oil vis, sugg switching to Rotella Synth to eliminate "romping" Anyone have any experience there?
\
Also, someone suggested just unplugging the EBPV. Anyone try that?

Nov 18, 2010 | 01:00 PM

CampSpringsJohn

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Quote:

Originally Posted by meporsche

The EBPV's don't work on either of my trucks. Deleted the one on my 97 when installed a new turbo. The romps are different. The romps sound like you hitting the gas and letting off real fast. Like reving the engine from 1000 to 2000 rpms real quick. You would not drive with the engine romping if you have an automatic. My truck does that on occasion, and I would not shift it into gear with the engine carrying on like that. Switching to synthetic is not a bad idea. I run it in both of my trucks. That said, my 97 still romps occasionally.

Nov 18, 2010 | 01:18 PM

meporsche

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This is just a consistent roll of a couple hundred rpms up/down/up/down etc. More noticeable at low rpm, you can watch the tach just wave a little bit at idle, from 6-700 rpms or so back and forth.

I'm going to switch to synth oil anyhow, longer between changes if nothing else.