Truck runs bad after extended idling - Diesel Forum

Stan Wright · 12-05-2002, 10:05 AM

When I go to a motor vehicle accident my truck idles for 20-30 minutes usually. The last few times when I'm driving away my truck runs very rough (feels like it's missing) and dies. I can put it in neutral and restart it but it still runs poorly. If I shut the truck off, then restart, it will run fine for months (or the next time I idle for a long time). Any ideas?

jetskier · 12-11-2002, 06:24 PM

Have you tried raising the idle speed with a home made AIC (i.e. brook stick cut to fit). The diesels get the electronic version that does the same thing. I think you may be getting a lot of raw fuel or fuel that has not burn completely causing the valves to stick a little or temporarily fouling the spark plugs. My old Ranger had similar problems with extended idling. When you get it hot enough to burn that stuff away it away ran good again.

Stan Wright · 12-12-2002, 12:05 PM

I wish they made an AIC for the V-10. My gut feeling is that I have a sensor problem, since I can restart the truck and everything is fine. The last time this happened the 'Check Engine' light came on. It would flash and I could hear a relay clicking corresponding with the flashing light. Any recommendations on diagnostic software I can use on a laptop?

monsta · 12-12-2002, 12:13 PM

Stan, How many miles are on your truck?

I am going to guess the O2 sensor. At idle i think the truck works off of a closed loop system. The O2 sensor will adjust the mixture based on the O2 content in the exhaust. I believe that it may be unable to re-compensate after an extended idle period but resets itself upon restart.

Replacing the sensor is usually part of a gas engine tune-up at 100K (I believe) but extended idling can cause this to be moved up. If you are under 70K it will be covered under warranty provided my guess is correct.

Have you had a local auto parts store, like Autozone, do their free OBDIIscan? The setting of the light should store the code in the computer, although some malfunctions do not store. I do not know why...

BTW, did you also post this over at ford-trucks.com? Someone else over there has the exact same problem.

Autotap.com has diagnostic software.

Stan Wright · 12-12-2002, 02:14 PM

My truck has about 45K miles. The O2 sensor idea sounds like one to investigate. I guess I'll crawl under the truck to make sure the O2 sensor wires haven't gotten against the headers or something like that. I'll also check out the Autotap software. I'd like to get one of the SCMT tuners, but I already have a SuperChip and a TruSpeed converter, so the SCMT would be alot of duplication.

Yes, I also posted at Ford-Trucks.com. I haven't been able to access the site for about a week now. The page load hangs up about halfway through.

Thanks for the info.