Help!!! high RPM at idle

[Mike94GT]

Anyone know what would cause the rpms to be high (1500-2000) at idle? Had the check engine light on intermittently over the past couple weeks. Then one night I came home, shifted into park (AODE), and the tach just jumped up there. Couldn't get the speed back down. I have a stock 94 GT vert with about 83,000 miles. Other symptoms include a stumble on acceleration, and it was hard to start after shutting it off with the rpms that high. Anyone have any ideas? It would be most appreciated....

-Mike-

 

[NYSTANG]

Anyone know what would cause the rpms to be high (1500-2000) at idle? Had the check engine light on intermittently over the past couple weeks. Then one night I came home, shifted into park (AODE), and the tach just jumped up there. Couldn't get the speed back down. I have a stock 94 GT vert with about 83,000 miles. Other symptoms include a stumble on acceleration, and it was hard to start after shutting it off with the rpms that high. Anyone have any ideas? It would be most appreciated....

-Mike-

does it only stall when its warm?

 

[viperos]

my taurus used to do that, really weird too... it used to chunk when I put it into gear after the high rpm thing too... no idea what fixed it, it just stopped one day... hasn't done it since, that was almost a full year ago now...

 

[mustangt562]

Happen to me too, its the..........

Anyone know what would cause the rpms to be high (1500-2000) at idle? Had the check engine light on intermittently over the past couple weeks. Then one night I came home, shifted into park (AODE), and the tach just jumped up there. Couldn't get the speed back down. I have a stock 94 GT vert with about 83,000 miles. Other symptoms include a stumble on acceleration, and it was hard to start after shutting it off with the rpms that high. Anyone have any ideas? It would be most appreciated....

-Mike-

Its called a "idle air controle valve" it is connected directly onto your throtle body and it lets air into the intake when the throttle body is closed so the car can idle. well when they go out the valve hangs open and you get high ass rpm's at idle. its a $30. part and you can do it yourself with no problems.
may take you like 30-45 minutes. its really a no brainer to swap out piece of cake.

 

[mo_dingo]

Yep, Idle Air Control Valve. [size=+1]BUT DO NOT BUY IT AT AUTO ZONE!!![/size]

The part that they sell DOES NOT FIT. It's part number TV206 at autozone. The instructions ask you to flip it backwards, so the solenoid points towards the front of the car, instead of the back. But the oil fill tube prevents mounting it in this fashion.

Go to pep boys. They have one made by Borg-Warner and it's a factory rebuilt part. It works great! It fixed my high idle problem.

I just went through the big hassle w/ the IAC valve. I didn't read the instructions (they were hiding at the bottom of the box. I thought my problem was something else.

But make sure that your problem is with the IAC valve itself. There is a gasket between the IAC valve and the throttle body. Check for major cracking before you go buy a brand new IAC valve ($69.99).

You can remove the IAC valve, soak it in carb cleaner, and put it back on. That might fix your problem. But if it doesn't help (didn't help in my case), get a new one.
Scott

 

[viperos]

personally, I'd order one from FORD... just because that's the type of guy I am... I wouldn't hassle w/ the schucks/autozone/napa guys...

 

[Mike94GT]

Thanks, to all. You guys are the best. I'll try it. Let ya know how it goes. Man, do I miss the days when a computer was something that just sat on a desk...

 

[Mike94GT]

Ok, guys, changed the IAC valve. The rpms seem to be normal, but it still runs like crap when cold. At least for a few minutes till it warms up. Kinda lopey, like a carbureted car with a bad or stuck choke. Anyone know what could cause this? Also, the fan runs right away, even before it warms up. Any ideas on this? Maybe a bad ICT? Coolant temp sensor? Could the O2 sensors do something like that? Or maybe EGR? Those are the possibilities I've come up with, but I'd rather not spens a whole lot of money trying the "process of elimination" method. Thanks in advance, guys!

-Mike-

 

[mo_dingo]

The O2 sensors are HEGO sensors. (Heated Exhaust Gas Oxygen). The computer pretends they do not exist until the car is warm.

Disconnect the battery for 20 minutes, then reconnect and drive the car for 20 miles. If the computer detects a problem with one of the sensors, then your CEL should come on sometime during the first 20 miles. Whether or not the CEL comes on, run the codes anyway. Post back as to what you get.

The ECT sensor is your likely problem, but lets see what the computer thinks first.

http://www.allfordmustangs.com/Detailed/445.shtml
That is a link to a site w/ info on how to run your own codes. A multimeter is not necessary. You can watch the CEL flashing inside the car. If you need help, post back.

Scott

 

[Mike94GT]

Thanks a million, Mo Dingo! It was the coolant sensor. Funny thing is, I had changed that in the fall when I was trying to troubleshoot a stalling problem, so I didn't even consider it. But when I checked the replacement sensor with a multimeter, the reading was in orbit!. Being the pack-rat that I am, I still had the original sensor, and when I checked it, it was fine. (Shoulda done that in the first place... ) Car runs fine now when I start it.
Thanks again!

-Mike-

 

[mo_dingo]

No problem. Thanks for letting me know my brain is still functioning properly!!!
Scott