chugging/surging @ idle when cold
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Joined: Jul 2007
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chugging/surging @ idle when cold
My 2000 EX V10 has started chugging or surging while idling after start-up. Still idles a little rough once the engine warms up, but I'm not sure I would notice if I wasn't already aware of an issue. Also, my city MPG seem to have dropped by 2-3 MPG. I haven't noticed a change on the highway. My first thought is fuel filter, but it and the air filter were both changed less than 10k ago. I changed a COP and all 10 plugs in August due to a miss, and this issue started earlier this month. What else should I be checking?
Logistics Pro
Joined: Aug 2007
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From: Millersburg, OH
The surging and idling problems sound like the IAC needs cleaned or replaced. It could also be that the MAF sensor needs cleaned as well since you also reported a drop in fuel mileage. The O2 sensors could also lead to a drop in fuel mileage. How many miles you have on it?
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Not quite 125k. I'm aware of the MAF and have tried cleaning it. I'm not sure what or where to find the IAC? Won't a bad O2 sensor generally throw a code? It's not thrown a code sense I change the bad COP out.
Logistics Pro
Joined: Aug 2007
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From: Millersburg, OH
The IAC is on the backside if the throttle body. I don't think I have a pic of it but I will look. It's under the cowl and is bit of a pain to get to.
O2 sensor can degrade as they stack up miles. They aren't "bad" but they lose their ability to sense the exhaust mixture causing it to show lean and fooling the PCM into richening the fuel mixture. Usually 100K is what is batted around here as the mileage to replace them.
O2 sensor can degrade as they stack up miles. They aren't "bad" but they lose their ability to sense the exhaust mixture causing it to show lean and fooling the PCM into richening the fuel mixture. Usually 100K is what is batted around here as the mileage to replace them.
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A little update on the symptoms. I've noticed the idle-chugging only happens when sitting in gear, esp. reverse. Idles fine in Park. I've also noticed this happening after the engine has warmed up. Does this still sound like an IAC problem? I took it on a 350 mile round trip this weekend and highway mileage and performance still seem normal. We'll see how the rest of this tank goes in town and I'll report back.
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Senior User
Joined: Mar 2008
Posts: 342
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From: Maple Ridge, Canada
Since you feel it idles fine in park and more pronounced in reverse than forward
Sounds like a trans issue is starting to show up.
Your grasping at straws. What you need to do is get a good service manual and use it to systematically pin point the problem. Or bite the bullit and take it to a tech.
Good luck.
Sounds like a trans issue is starting to show up.
Your grasping at straws. What you need to do is get a good service manual and use it to systematically pin point the problem. Or bite the bullit and take it to a tech.
Good luck.
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New User
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I don't buy the transmission idea. I should have been more specific. It surges/chuggs when in gear with the brakes applied, apparently when it goes to a lower idle speed? The surge goes away if I give it just a little throttle. I'm pretty convinced it's a fuel delivery problem of some sort. I feel like it should be something simple and I'm just not looking in the right place, but I could be completely wrong.
Senior User
Joined: Mar 2008
Posts: 342
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From: Maple Ridge, Canada
Really I was suggesting more along the lines of a Torque converter issue or one of the components involved with its function or the wiring leading to those bits.
If you post in the Clutch, Transmission, Differential, Axle and Transfercase section you may just luck out.
I drive stick so I,m really not well versed in Autos.
All data has decent online manuals for reasonable cost compared to the ford online subscriptions, or not.
Good luck.
If you post in the Clutch, Transmission, Differential, Axle and Transfercase section you may just luck out.
I drive stick so I,m really not well versed in Autos.
All data has decent online manuals for reasonable cost compared to the ford online subscriptions, or not.
Good luck.
Post Fiend
Joined: Jan 2002
Posts: 5,859
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From: USA
The Iac is not a expensive part,it becomes carbon clogged an slow to react.
Did you use new boots on all the cop's and dilectric grease?
They tend to crack after time and will alow moisture in an cause misfires.
Change the Iac first ,then think about the boots.
Rich
Did you use new boots on all the cop's and dilectric grease?
They tend to crack after time and will alow moisture in an cause misfires.
Change the Iac first ,then think about the boots.
Rich
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Joined: Nov 2009
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I had the same problem with my 99' idling rough, real rough, but when you got going it all seemed fine, took it to the dealership, a vacuum line had collapsed in the pcv system somewhere, i dont know many other details, maybe that will get you on the right track