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Jun 5, 2009 | 05:17 PM

SMarquez

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Tuned

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Another Rough Idle Thread

Hi all, I have a 2000 F250 (102,000 mi.) that has been bulletproof until this morning. I fired her up and had a rough fast idle. When it was warmed up it was hanging at about 1100 rpm then went slowly down to 750 or so. I disconnected 6 COP wires and couldn't hear a real problem. I did not get a check engine light and haven't had it scanned yet. My first thought was a COP or boot but no change in the 6 I checked.The only issue that is out of normal for me is that we were in Las Vegas yesterday and filled up at a Rebel gas station and drove 230 miles home. Any ideas?
Thanks,
Steve

Jun 5, 2009 | 09:30 PM

BareBones

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From: Burnsville, MN

Check the remaining four, and clean the Mass Airflow Sensor?

Jun 7, 2009 | 03:04 PM

krewat

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From: Long Island USA

Check for a vacuum leak. That PCV elbow is suspect.

Jun 7, 2009 | 08:05 PM

SMarquez

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Tuned

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The PCV elbow was collapsing but not leaking, replaced but did not correct the problem. DC'c the IAC, engine stumbled bad so on that basic test that is OK. I do have a CEL now, my guess is when I DC'd the IAC. It seems like when I DC'd the #10 plug there was no change. Is there a way to bench test a COP? I'll do the Auto Zone code scan tomorrow to check from there. Tracing vacuum hoses on this thing is a bitch. Could it be the EGR? My son's Astro had a real bad stmble but ran 1/2 throotle up fine.
Thanks all

Jun 7, 2009 | 09:18 PM

BareBones

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From: Burnsville, MN

The only practical test is to buy one new COP and rotate it through the cylinders.

Jun 8, 2009 | 06:48 AM

krewat

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From: Long Island USA

The IAC will not throw a code for a 2000. The IAC functional test is calibrated out.

https://www.ford-trucks.com/forums/5...t-come-on.html

Jun 8, 2009 | 09:19 PM

SMarquez

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Tuned

Joined: Jun 2004

Posts: 319

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Cleaned MAF and throttle body valves, no help. I can't hear a difference in any cyl. when I dc the cop's. Apparently in California chain stores can't do diagnostics anymore so it's off to a shop.