Rev at Cold Startup

[Tiggie]

On teh '88:

After sitting overnight, I go out to start the wagon. Engine starts, then starts a cycle of regular idle for 2 seconds/rev to about 2500rpm for four seconds. It repeats it 5-7 times, then idles fine. You can hear it sucking air right before it revs up. If you put in in drive during the 2 second idle period, it idles perfectly fine.

Idles fine otherwise, starts fine when hot, never stalls.

It's been doing this since last spring, so it's nothing new. Just wondering what might be the problem because revving it up cold in ten degree weather can't be good on things. No codes other than the EGR (34). I'm thinking an IAC misfunction. Any suggestions?

[86VickyLX]

Check the ACT sensor on the lower intake, in between fuel injector #5 and #6 and see if it's covered in stuff. If it is you can clean it up and see if that changes anything.

[gadget73]

that or the coolant temperature sensor is funky. The air rush is the IAC, but more than likely its getting a signal to open, not just screwing up on its own. Could be sticky and over-shooting the target speed tho.

[Glen]

Mine will do the same thing, only not so high. It will go to 1600 -1700 with the AC on and about 1300 - 1500 with it off. It gets a little higher when it is cold outside. It has been doing it since I got it. I know it is no help to you, but at least you know you are not the only one.

[86VickyLX]

Is your A/C working now mang?

[Tiggie]

A/C and Smog Pump are gone. I'll check the ACT to see if it's clean. Should be, it's pretty clean under the hood (though not pretty).

I used to get a code for ECT, but not the last time I pulled the codes. I guess it's possible. I replaced it and was still getting the code for a while. I'll get out my EVTM and do a little wire prodding to see if the wires are okay.

[86VickyLX]

The car was warmed up completely when you pulled codes correct?

[Tiggie]

The car was warmed up completely when you pulled codes correct?

Yup. Pulled them after a 1+ hour drive, it was at 200 degrees F according to the gauge.

Until I get home this weekend and test the wiring, I've just been dropping it in gear ASAP before it gets a chance to rev up. Once it's in gear, it's perfect.

[86VickyLX]

Yup. Pulled them after a 1+ hour drive, it was at 200 degrees F according to the gauge.

Until I get home this weekend and test the wiring, I've just been dropping it in gear ASAP before it gets a chance to rev up. Once it's in gear, it's perfect.

That sounds exactly like what happened to me when my ACT went bad, but this was when it was warmed up. But the same thing, if I put it in gear it would idle normally. Also if I put the AC on it would idle normally.

[Tiggie]

That sounds exactly like what happened to me when my ACT went bad, but this was when it was warmed up. But the same thing, if I put it in gear it would idle normally. Also if I put the AC on it would idle normally.

I'll definitly check out the ACT when I get home to my lovely toolbox, code puller, and voltmeter. Thanks!

[86VickyLX]

No problem. I hope you find out what's wrong.

[Archangel]

TPS! That little bugger was causing me all sorts of high-idle issues last year. Check the TPS, that may be it for you too.

[Tiggie]

I replaced the TPS last year with a new Ford one, so I hope it's not bad again. I was having problems with the car stalling back then. The old one tested fine, but the stalling stopped when I replaced it (sure do miss my parts car for parts diagnostic purposes).

Anyway, I'm looking at my service manuals. Mainly the Engine/Emission manual. I'm getting a code 51 for the ECT sensor again. Same one I used to get. EEC wiggle test indicates a continous fault somewhere. I am wanting to test the wiring and the manual says I need a breakout box. I eBay'd them, and they are more expensive than any box I've ever owned. How can I test the circuits without probing the EEC connector and without a breakout box?

The wiring physically looks fine on the outside.

The ECT sensor tested good. Will check the ACT sensor whenever I get a chance, probably later this week.

[86VickyLX]

I know it's highly unlikely but it could be the computer.

[gadget73]

well, without a breakout box, you're sort of limited to probing the ecm connector. Basically unplug it from the ECM, and check for continuity from whatever pin to the ect. It should be 1 ohm or less.

Thought, try the salt and pepper shaker fix. The ECT wiring goes through that connector if I'm not mistaken. http://fordfuelinjection.com/?p=85