off idle hesitation

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Aug 27, 2009 | 03:56 PM

bryanj

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off idle hesitation

Drove my "new" 99 F350 to work this morning. The temps were in the low to mid 50s. I started the truck, fired right up and let it run at idle for about 5 minutes. I left home and drove through 30-40 mph streets for about 5-10 minutes and then opened it up to 45-60 mph for about 10 miles. After about 8 of those miles I noticed what felt like a slight hesitation or slight surge off of idle. When I stopped at an intersection, I very slowly accelerated just off idle and it felt like I was going a little throttle to no throttle, back to a little throttle. If I get into it just a little more, no problems.... No CEL at this point. I drove this truck back from California a couple of weeks ago and had no problems. I know the glow plug relay is bad; haven't replaced it yet. I also drove it later this morning and this afternoon and this did not happen. I would venture a guess that this happened around 1500 rpm.

I read one post that talked about the UVCH clip. Before I pull the valve cover off, any other thoughts? I haven't changed the fuel filters yet if that is of any help. The truck as 23,000 miles on it.

Bryan

Aug 27, 2009 | 04:28 PM

MR5x5

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From: Issaquah, WA

Might try unplugging the ICP and repeating. It's free and quick. When you unplug it, look inside the plug for any sign of oil. Mine stumbled at idle when my ICP went...

Aug 27, 2009 | 04:58 PM

bryanj

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Just to clarify, idle is fine, its when you just start to give it a little throttle. I'll give the ICP a try....

Bryan

Aug 27, 2009 | 05:08 PM

zx250

Of the next Riffraff East

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From: Concord NC

23,000 miles? On a 99? Want to sell it?. Check your oil level and make sure it's not time for a change. Don't think it's an ICP problem or a UVCH problem. Could be a failing TPS (throttle position sensor). That's a tough on to diagnose and even with a scan tool is hard to narrow down.

Aug 27, 2009 | 05:46 PM

countrykid_86

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I agree it probably isn't your ICP, I had a problem with the engine lurching a couple months ago and it was a EBPV problem, but your problem sounds worse than that. Have you changed the fuel filter lately?

Aug 27, 2009 | 06:50 PM

bryanj

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Quote:

Originally Posted by zx250

Yes, 23,000. Someone bought this for recreation (slide in camper) and after a few years gave that up and didn't drive it much more than 5-6 times a year. Before I bought it, I think it sat for months on end without moving. Where is the TPS on a diesel? I know they are on the throttle plate on gas engine, but this is my first diesel.

Quote:

Originally Posted by countrykid_86

No, I drove it immediately from the used dealer lot to a Ford Dealership to get the oil changed and a quick check over. They wanted to change the fuel filters but wanted $155 to do that. I figured I could do it far cheaper. So your thinking that it may be a fuel pressure issue at low RPMs? I drove it home from work this afternoon after starting this post and the problem was NOT present. It only did it this morning.........

Bryan