Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

97 Ford Escort Revs hi sometimes

This is an Escort Wagon.
Has anyone CURED an Escort that goes to 2500RPM or more, for no reason about once a week?
I have seen all the suggestions.But never a cure for it.
Has anyone had this happen ,then FIXED it?
The revs go to normal sometimes by itself in a minute or five.Sometimes hi revs dont stop until you turn it off for a while.
The next time hi revs happen might be two weeks later y’ never know.Or it might be four days Y’ never know.

You have a system called an OBDII system that monitors your car’s crutial things and stores “fault codes” in a computer for future reference. Stop by a local parts store and ask them to “read” the “fault codes” and print them for you. Then post them here. Many parts stores will do this for free. If not, the fee should be minimal.

Chances aee good that it’ll turn out to be the Idale Air Control (IAC) systen that controls your idle speed. But lets’ try loooking at the codes first.

Tnx ‘same mntn bike’ , but IAC has been done and other things too.
No code is displayed. I forgot to say that. The hi revs are so far and few between that it is very mysterious. One experienced mech. suggested that it is not due to vacuum leak because it would not be intermittent- a leak is a leak and is permanent. I even tested the vacuum with a meter.
That is why I asked if anyone has ever FIXED this problem . :slight_smile:

Further -forgot to say that the hi revs happen under many different conditions.
1.Cold start 2. warm start 3.after coming off hiway to city traffic at a stop light
4.just driving along in traffic.
5. Sometimes you can shut down and restart to make it stop. Not often does that work.
6. Sometimes you can hit the accelerator in neutral and hi revs will stop -not often does that.
This has been going on for about a year. Sometimes a month before the next hi rev happens.

Forgot to say that the carpet or rug is not getting on to the accelerator pedal.

@jcishere if you mean that you checked for vacuum leaks with a vacuum gauge, that is NOT the proper way to check for vacuum leaks.

The most efficient way is to use an evap/smoke machine.
Another method is to spray carb cleaner at suspected leaks while the engine is idling. If the idle changes, you’ve found your leak.
Using your fine-tuned ears will also identify very obvious vacuum leaks at idle.

It’s not impossible to get a defective IAC valve. Try this.

When the engine is at operating temperature, take the handle of a screwdriver and tap on the IAC valve. If doing this causes the engine idle to change the IAC valve is defective.


When I had the same issue with my '88 Ford Escort several years ago the problem was a bad ECU. I changed it and there’s been no problems since.

I assume that when you said “no code is displayed” you meant that you checked for stored codes and not just the light?

I went searching a bit to try to find out if there were intake manifold gasket leak problems with this engine and found this:

Note that sticky valves will manifest themselves as unstable vacuum, and I did pass the link on, I’d still want to test for vacuum leaks. They can and do cause a wandering idle. I’d use ether (starter fluid) as my test media of choice, but follow db’s procedure.

Note too that vacuum hose is dirt-cheap by the foot. Sometimes on an older vehicle it’s easier to buy a long length and replace the hoses one by one.

Other possibilities that could cause a wandering idle are wandering timeing due to a bad crank speed sensor, cam position sensor, a bad MAF or MAP sensor, or a bad upstream oxygen sensor.

You mentioned that there were other things you’d done. What were they?

And I hope you realize that what stopped the symptom for another person may not be the same thing that’ll stop the symptom for you.

tnx same mntnbk - 1. Yes ,no check engine light. So I should hook up myOBD2 tester and look for codes then. I think the Ford dealership could not see any codes tho. 2. Thanks for the link to 3. I might not suspect a sticky valve because the engine is only 2yrs old Nov 2012.
And wandering idle is minor compared to the extreme, sudden hi revs that come and go.
4. I like your starter fluid method of testing for vac leaks - saw it done on youtube. I don’t suspect vac leaks much because the hi revs are soooo intermittent , unlike vac leaks.
An old ford dealership mechanic did not think vac leak.
5. MAF was replaced ,and one short oily dry vac line was replaced, and the ECTemperature was changed.
Ford here on the west coast of Canada cannot get Ford IAC valves for '97 escort anymore.
I have a new aftermarket IAC from Lordco suppliers.
When that was installed for a week or two it let the revs be even higher whenever the revs went hi. So the ford mechanics put my old one back in.
The revs only went hi for a short while when they had the car.
So I try to figure it out ,with help ,by myself because of the intermittency.