Contour Enthusiasts Group Archives Forums General Troubleshooting SVT engine revs up by itself

It's either the IAC valve or the MAF sensor. My car seems to have a terminal case of this. I'm on IAC valve #2 and MAF sensor #4 (in the last 12 months)!!!

It is most definately NOT throttle "hang". The engine revs up 1000rpm or so between shifts.

Oh no.... Here we go. I think mine is developing the same thing.. :rolleyes:

I had the EXACT same problem. It would occur only on warmer days, and would be noticably worse on humid days. Guess what? It is throttle hang. Correct me if I'm wrong here; pumping air into the engine will lean out the fuel/air mixture which will increase the rpm's. The throttle hang/rev increase is the result of the engine pumping to much air as part of an effort to control emissions. Putting the copper plug into the air line acts as a restrictor and doesn't allow the engine to pull to much air.

I could be all, doesn't matter. What matters is that the problem should be fixed with the plug. I got sick of my car revving up to 4500 rpm's, and finally went and broke the bank on some $0.25 hardware.

Double-checking your problem report:
1) the revs refuse to drop when you put in the clutch to shift, sometimes even increaing on their own
2) this problem doesn't happen when the car is sitting at a stop light, only when it's in motion
3) the problem mainly seems to happen on warm and humid days?

And the *BIG* question: the throttle hang fix (copper cap) took care of the problem?

Check the vacuum lines going to the IAC. If there is a leak somewhere, the IAC won't have enough vacuum to do its job, and the idle will be high.

I feel like MilwSVT did when writing that post. I had the same problem. 2 dealers neither one knew what the hell it was or how to fix it. I bought the car used with 31K miles. Up until 37K I had no problem whatsoever, then the "RPM surge," as I've heard it called by someone else, began. Strangely enough at 39K (about 1 month)the problem disappeared. Now at 40K it has not happened for weeks, knock on major wood, and I have taken the car on long trips, short trips, traffic, you name it.

One thing I never noticed was the temperature or the humidity outside while this was happening. Your posts got me thinking and it may have had something to do with it as this is the first summer I have had the car. Sorry for the long post but I feel somewhat relieved that others see and understand the problem and not dismiss it as throttle hang (although the TH fix may work in this situation too, I haven't tried it.)

indeed the engine will rev up 500rpm from time to time. I'd say 80% of the time it's between gear shifting, particularly annoying when down shifting and that the car accelerates by itself.
It took me a while to figure that out (I thought also it was only during hot/humid days) ... the problem only appears when the A/C is on (during hot/humid day of course, but also to remove the haze on the windshield). The car has been in the 2 different dealers (the first one couldn't even see the problem after repeated visits among other things ), the second one told me that the computer couldn't find anything, that SVT engines are purposely tuned like that for the American drivers and that I'm not used to it, being French ... I could understand a special tuning, I can't agree however that this is a normal behavior, a car should NOT accelerate by itself for any reason in the world.
Anyway ... they had to change the catalytic converter (39k miles only), hopefully that's one of the 2 things Ford fully cover until 80k miles apparently.
I did 1-2 try with the A/C on and didn't feel the problem anymore, will see in the long run

My car is in the shop now for the 5th time (in less than 5K miles) with this problem. They have replaced the IAC (idle air control) twice and reprogrammed the computer once. The IAC replacements seemed to work for a little while. Who knows what they will do this time.

The dealer says Ford has no bulletins out about this. I'm wondering if we shouldn't write a group letter to Ford/SVT describing our individual experiences with "RPM hang".

If anyone is interested in sharing, email me your story (pinkrton@mcw.edu). I'll combine them and send them to Ford. Can't hurt, I suppose.

My 99 svt was trouble free until 37500 miles. The first sign of trouble was a horrible "moosing" sound. It happened every now and then at first. It soon began to happen all the time. A few days after the moosing started, my rpms began to hang during shifts. Then, a short while later the
rpms began to hunt all over the place. It would rev up high, surge up and down etc. Twice it died on me stopping for a light.
I decided to try the "throttle hang fix" with the copper cap. It took about 20min..
That was 12000 miles ago, no trouble with it since.

The dealer checked with Ford. They know about this problem, but there is no fix. Argh!!!

I now have a car that I won't drive in the winter and I *can't* drive in the summer!