Strange Idle issue

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Jun 16, 2015 | 02:10 PM

The Krustinator

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Strange Idle issue

Have a 2003 F-250 with 174,000 miles. Recently replaced CPS and ICP and it's running much better. It normally idles at about 700 rpm. Lately, after driving for any distance above ~40mph, when I come to a stop, the rpm won't drop below about 850 rpm. If I shift to neutral (automatic trans), the idle drops to around 700. At the next stop sign/light, it's back up to around 850.

Any suggestions?

Thanks

Jun 16, 2015 | 02:17 PM

Whitey Ford

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Were they OEM parts?

Jun 16, 2015 | 04:13 PM

The Krustinator

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The CPS was put in by the local Ford shop. The ICP I got off Amazon and installed it myself.

Jun 16, 2015 | 04:57 PM

Whitey Ford

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Do you have a scan tool that you can monitor with? What issues were you having that lead you to change CPS and ICP?

Jun 16, 2015 | 05:44 PM

The Krustinator

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Don't have a scan tool. Looking around for one.

The symptoms were the classic ones, rough idle, stalling a low speeds, surging on the highway. All of those went away after the ICP change.

Jun 17, 2015 | 08:11 AM

Whitey Ford

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Where are you located? Maybe someone with an AE here is close to you and can do some live monitoring. Most of the time AE will point you in the direction of the problem without wasting your time and money.

Jun 17, 2015 | 12:48 PM

The Krustinator

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I live in Covington LA. I have been looking around for an AE. Supposedly there is a good shop over in Amite.

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Jun 17, 2015 | 01:24 PM

Whitey Ford

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You can get AE from Riffraff Diesel for the cheapest I've seen. It will save you big money on this issue and future issues. 1 trip to a shop will cover it's cost, most of the time.

Jun 19, 2015 | 06:14 AM

#10

The Krustinator

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While I hunt for an AE, could this be a transmission sensor issue?

Jun 19, 2015 | 07:14 AM

#11

Whitey Ford

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The AE would tell you if it was. If you didn't have the issue before you changed CPS and ICP, that is where I would start. The reason I asked if they were both OEM is because aftermarket sensors have a bad reputation of causing new problems.

Jun 19, 2015 | 10:44 PM

#12

Mohawkwoodman

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Icp solenoid should be verified and looked over with a scan tool to see the actual running pressure 500-700 should be normal, then get that verified by swapping the icp sensor with a mechanical guage. Hows the oil and is the air filter breathing or is it the classic air starved diesal that runs poor? Ive seen a few that never start due to choked air filters.