Engine runs funny when AC is on?
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Engine runs funny when AC is on?
I have a 2000 expedition, and when I have the AC running the RPM gage and the engine jump from 1500 to 3500 RPM back and forth while the truck is at a stop. When you are giving it gas it stops jumping around. When you turn the AC off the truck runs fine (even at stops)? I took it to Ford and they said that it might be the idle control valve, they replaced it but after 2 days it started again. Ford said that they dont know what could be causing it because the CHECK ENGINE light does not come on and the tech does not know what to look for. Does anybody know what I can do?
Thanks.
Thanks.
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From: North Texas
Holy cow someone is having the same problem that I'm having!!! I've checked the PCV and it's perfect; cleaned out the IAC valve although that looked fine; Checked air filter; ran fuel-injector cleaner, etc. I'm so glad to know that I'm not the only one having this problem, although my RPM's only jump to 1500 or so and then back to normal. Like the above, it's only when the AC is on.
To recreate the problem, I have to drive for a while (let the engine warm up); have the AC on; have the truck in DRIVE and be stopped at a stoplight or stopsign.
I just ordered a new TPS off of eBay on a hunch. Anybody have any experience with these symptoms?
To recreate the problem, I have to drive for a while (let the engine warm up); have the AC on; have the truck in DRIVE and be stopped at a stoplight or stopsign.
I just ordered a new TPS off of eBay on a hunch. Anybody have any experience with these symptoms?
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sounds like the IAC to me...Could be the TPS though too. I had that problem with my mustang all the time. It would go away after I cleaned it out with carb cleaner but would come back sometimes within an hour...Bought new IAC and no moe problems!
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From: North Texas
Thanks for the response, Black-n-tan! I'm a little skeptical about the IAC since "Chevy Sucks" has already replaced that...
If all else fails I will have to try that though. I'm just wondering if it isn't something with the A/C system since that's the only time it happens.
It was a little cooler today in Texas since we had a storm blow through. I noticed that it wasn't doing the RPM jump thing today even though the A/C was on. I realized that it had been blowing full blast when I had the problem, so I pushed the "Max AC" button while I was at a stoplight and voila - jumpy RPM's. I normally idle at 650 RPM's and it was jumping up to about 1,000 and then back to 650 today.
It's almost like the load that the A/C puts on the engine is "confusing" it... Like it doesn't quite know how to compensate for the Max A/C and find just the right idle speed. I'm assuming this has to do with the compressor since the blowing motor is electric, right?
So confused...
By the way, "Chevy Sucks"... Sorry I hijacked your thread. Feel free to add your 2 cents any time
If all else fails I will have to try that though. I'm just wondering if it isn't something with the A/C system since that's the only time it happens.
It was a little cooler today in Texas since we had a storm blow through. I noticed that it wasn't doing the RPM jump thing today even though the A/C was on. I realized that it had been blowing full blast when I had the problem, so I pushed the "Max AC" button while I was at a stoplight and voila - jumpy RPM's. I normally idle at 650 RPM's and it was jumping up to about 1,000 and then back to 650 today.
It's almost like the load that the A/C puts on the engine is "confusing" it... Like it doesn't quite know how to compensate for the Max A/C and find just the right idle speed. I'm assuming this has to do with the compressor since the blowing motor is electric, right?
So confused...
By the way, "Chevy Sucks"... Sorry I hijacked your thread. Feel free to add your 2 cents any time
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No problem on the thread. My expedition is now doing the same problem when the air is off. Ford once again has no idea what it could be. The truck died on me the other day while my 17month old son was in the truck with me. At this point I am going to get rid of the expedition, and get the truck that I have always wanted, an F250. If you figure out what is going on with the expedition let me know. Thanks.
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From: North Texas
Originally Posted by Chevy Sucks
No problem on the thread. My expedition is now doing the same problem when the air is off. Ford once again has no idea what it could be. The truck died on me the other day while my 17month old son was in the truck with me. At this point I am going to get rid of the expedition, and get the truck that I have always wanted, an F250. If you figure out what is going on with the expedition let me know. Thanks.
Here's an interesting thought:
After I took out my IAC and sprayed it down w/some throttle body cleanser (I did some other stuff too, mentioned previously), it cut the problem down substantially. It's only jumping by 100 RPM's now, although it's only doing it with the A/C on...
It's possible that the you had a defective IAC, which was replaced by a defective IAC. I believe there are some diagnostic tests that you can do with a voltmeter, but I'm not sure if that's for the IAC itself or just the wire leading to it. At any rate, I'm going to change mine out in the next few months and see what happens.
Enjoy your F-250. I've always dreamed of owning a King Ranch F-250 but "momma needs new shoes"
Last edited by Mr.Novice; Aug 14, 2006 at 09:26 AM.
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Tuned
Joined: Aug 2006
Posts: 327
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From: Runnells, Iowa
I dont know if this will work or not but try cleaning this mass air flow sensor, those things can cause weird idling problems. Let me know if that fixes your problem. Good luck! Casey
P.S. use carb clean on it too. the little wires inside usually get debris on them, its usually black sooty junk.
P.S. use carb clean on it too. the little wires inside usually get debris on them, its usually black sooty junk.
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From: North Texas
Originally Posted by Diesel nut
I dont know if this will work or not but try cleaning this mass air flow sensor, those things can cause weird idling problems. Let me know if that fixes your problem. Good luck! Casey
P.S. use carb clean on it too. the little wires inside usually get debris on them, its usually black sooty junk.
P.S. use carb clean on it too. the little wires inside usually get debris on them, its usually black sooty junk.
I looked at the MAF and it scared me a little bit because those little light-bulb-looking filaments appear to be pretty sensitive. My question is, how do you actually get the sucker out of the intake, or do you have to? I detached the part of the intake that it's in, but couldn't just pull it out and I didn't want to man-handle it b/c of the sensitivity of the sensor, but I didn't know if spraying cleaner inside my intake would be a good thing or not either? I guess if I use a throttle body cleaner it couldn't hurt anything, but I would like to get it out so that I can inspect it more closely and clean it more thourougly.
'Preciate the feedback.
Tuned
Joined: Aug 2006
Posts: 327
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From: Runnells, Iowa
Yea thats true they are pretty sensitive. I have cleaned those before with carb clean and it didnt hurt anything. If you put that little straw on the nozzle of the can you should be able to reach those filaments. Can you see anything on those filaments?
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From: North Texas
Originally Posted by Diesel nut
Yea thats true they are pretty sensitive. I have cleaned those before with carb clean and it didnt hurt anything. If you put that little straw on the nozzle of the can you should be able to reach those filaments. Can you see anything on those filaments?
I'll definitely spray it down pretty good and let you know how it runs after that.
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