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Car revving by itself; engine won't turn off!

MistahYebba

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Hi there everyone,

So, my '92 Explorer has been kickin' pretty well lately.. I had a lot of problems with it when I first bought it used, but I managed to fix it all up.

That is... until recently again! Trouble has been brewing and I need help from all my braniac Ford friends here...

NORMALLY -- when I start the car, it starts right up and probably maxes out at 700RPM idle in Park.

Switching it in to Reverse always lowers that RPM right away to about 500. It's nice. Been purrin' like a kitten!

But starting last week, when I turn it on, it's been revving real high like someone is holding down the pedal during start up.

It peaks at maybe 1200RPM and slowly drops down... but switching in to gear makes it instantly drop down instead of slowly.

Now, at the same time that this HIGH REV at start up started occurring... a tick also developed.

This "tick" is a steady tick that changes depending on the RPMs.. It's very rhythmic.. Low RPMs = Slow tick. HIGH RPMS = FAST TICK. So I know it has something to do with a moving part in the engine or such. PLease advise on that :)

NOW.... pretty sure this is connected to the ticking sound. Yesterday, for the first time, it stuck revving high WHILE I WAS DRIVING.

I let my foot off of the gas to come to a stop and realized I was still revving at like 2500 RPMs...

So I had to put it in neutral to avoid crashing, but that made it rev EVEN HIGHER!

I turned off the car and turned it back on... but still revving mad high.

It was pretty embarrassing at a stop light :(

Anyway.. putting it in park, turning off the car, waiting a second, and turning it back on again seemed to correct the issue.

----

Fast forward to today; going to lunch from work, it started doing the same thing..

But turning it off didn't work this time!

This time, it was dieseling every time I tried to turn it off.. I literally COULD NOT turn my car off because of this. Every time I turned it off, it kept "blup blup blup" trying to stay running.

I kept turning the key on and off and on and off and on and off trying to get it to actually shut off, and eventually, it finally did...... but a TERRIBLE smell of exhaust/gas or whatever filled up the truck.

I had to get back to work, so I had to leave it in that state...

Now, I get out of work in 45 minutes and I'm worried that when I turn my car on, it will still be revving really high.. and to switch it into reverse from Park when it's stuck revving at 2500RPM or so I feel like won't be good for my transmission...

And trying to drive home will be dangerous :(

What can I do?

What is my problem?

I can fix it; I just need an idea.

Anyone even hear of anything like this?
 


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2stroke

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See if your alternator pulley wore through the bottom of the air intake tube. It would cause a huge vacuum leak, and could tick as it rubs.
 




Gadget X

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"Wiggle" all of your electrical connectors, just to make sure there's not a loose connector somewhere causing your problems, the unhook the battery for 15 minutes to "reset" the ecm. That will force it to re-learn everything, and may fix it! Good luck with it!
 




2stroke

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The thing is, even with the IAC all they way open, I doubt it would rev 2500+ RPM. It has to be some kind of big vacuum leak.
 




Rhett

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I'd say vacuum leak too. Check all the vac hoses on the intake manifold in addition to what was said.

Also check the throttle body...it has a vac port UNDERNEATH it that is sometimes missed.
 




natenkiki2004

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Actually... I'd lean towards the idle air motor and possibly sticking throttle plate. The IAC can cause a rev up that high because aside from regulating idle RPM, it also has acts as a stall preventer for scenarios such as letting off the throttle abruptly (shutting off air to a fast spinning engine would cause it to die) and engine braking. If for some reason it's shorted and is getting constant power, I'd imagine it could rev you up. Quick test to check, just unplug it and run the engine. It's got a spring in it to push it back, the ECM puts power to it to open it.

As far as the ticking, let it go for now. It MIGHT be fixable but I'm not so sure it's worth the cost of parts to gamble. In my case, it's only fixable with new lifters and that's just not cost effective now.
 




Masterd

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Pull your intake hose off the throttle body side and make sure the rubber isnt coming apart and jamming the butterfly. This happened to me and it was pretty intermittent at first.

CIMG0187.jpg
 




MistahYebba

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Masterd hit the nail right on the head.

This is what I discovered last night -- came back here to see what people said and that's exactly what was wrong.

Thanks for all the help guys!

The ticking noise was because I had no oil.. .but my oil gauge is showing fine so clearly that's broken. :(
 




timtimtimajim

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Your oil pressure gauge is just a dummy light. So as long as the oil pressure is above 5 psi it will read normal.
 




2stroke

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There is also a check oil light that comes on when the oil is low. Either the sensor is bad, or the bulb is burned out. Anytime in the future, if you hear any kind of strange noise. The engine oil is always the first thing to check.
 




Masterd

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Wow I was right?????

It was just a long shot :D Who would ever figure that this particular failure would happen to another truck
 




2stroke

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Its happened to me too, but I noticed it immediately. I now put a little petroleum jelly to help them back on without ripping.
 




Centaurious

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Any idea where to find a replacement rubber piece? I looked online but had no luck.
 




natenkiki2004

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Junkyard would probably be your best bet. You can repair your old one though. I've had success repairing intake boots with Permatex Black. Very flexible and sticks like nobody's business.
 




Rhett

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Junkyard would probably be your best bet. You can repair your old one though. I've had success repairing intake boots with Permatex Black. Very flexible and sticks like nobody's business.

How about the end of the tube itself? Mine is a little boogered. Maybe plastic weld?
 




natenkiki2004

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I still vote for Permatex Black. It's like a rubber that you can shape and mould. Unless yours is really far gone, then it's probably time to look at a junkyard.
 




Rhett

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I still vote for Permatex Black. It's like a rubber that you can shape and mould. Unless yours is really far gone, then it's probably time to look at a junkyard.

Permatex Black can be used for plastic repairs?

I knew it worked with rubber. But I did not know it could bond plastics
 




natenkiki2004

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Permatex Black can be used for plastic repairs?

I knew it worked with rubber. But I did not know it could bond plastics

As far as I know, the 1991-1994 is a hard rubber. If it was plastic, it'd crack when cranked down. The early years like on my 1991 actually had a 3-piece intake tube and the middle part is plastic, the flat piece that sits over the radiator. I'd use plastic weld on that but not on the rubber parts.
 




Rhett

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As far as I know, the 1991-1994 is a hard rubber.

That's great news. For 15 years I thought it was some type of plastic.

This means I can finally do some work on it. I was always putting off repairing it since I didn't (yet) have a vac leak and I hate using that plastic weld stuff, where you have to mix the two tubes (one activator, the other some kind of epoxy).
 


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Centaurious

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That's great news. For 15 years I thought it was some type of plastic.

This means I can finally do some work on it. I was always putting off repairing it since I didn't (yet) have a vac leak and I hate using that plastic weld stuff, where you have to mix the two tubes (one activator, the other some kind of epoxy).

The tube between the air box and the throttle body on my 94 is plastic. Only the end seals are a rubbery type material. If I decide to repair the seals on mine I will clean them well with Acetone and cover the ends of the tube with wax paper before using the Permatex.
 




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