When I start my car, it it goes to 1500 rpms, then comes down to about 800, it will stay there, then I drive it and it stays at about 1300 idle, if I turn it off, wait a minute, then start it again, it will idle at 800, till I drive it.
It has been from 3degs to 40degs out here, it didn't start doing this till it got cold out.( below mid 50's)
Is this what happens whenthe ACTgoes bad?

Pat

 

you might want to check for codes.

 

yea i agree check codes, also could be you ect sensor ( engine coolant temp sensor)

 

+3 ..... (it's not a "+1" BTW....LOL)..... but yeah, you want to ask the EEC what she's working with (failure codes), run a DIY KOEO/KOER/Cylinder Balance Self-Test ....... if you have a faulty TPS, or an IAC sticking (not able to close all the way), it'll have those symptoms.

 

Ok!, I finally went and checked the codes. I got 41, 91, 33, 13, #8 cyl.
I had just put a different IAC & TPS (both used) and it cured my idle problem, and then it got cold out, and now after I start driving it the idle goes up and stays up at about 1200 rpms, otherwise it runs good, with no miss at normal or high idle.
I'm going to go out and clean the EGR, but right now it's 17 degs and snowing, I just took my 295X50'soff the rear of the car, so I can move in the snow, so I can go get some carb cleaner.
I don't drive my Mustang in the winter, but my tranny went out in my truck.
Can only one of these codes cause the others to read bad?


Pat

 

Assuming those are KOER codes + cylinder balance test....... 41 & 91 = you have a lean A/F, 33 = EGR is not opening when commanded (will not cause any problems or symptoms)...... 13 = Idle control too high, system cannot lower idle speed to target (lower) value....and #8 cylinder low in output = miss problem, or almost a miss.

 

I passed the KOEO, these codes were KOER
I did check the EGR, the diaphram is good, I didn't have time to remove it and clean it, but I did find the hose that attaches the plastic tube to it was split, and the tube broke, so I replace it with a rubber hose, but I didn't have time to drive it yet, I replaced most of them a year ago or so,but that should not give it a high idle, there should be no vacuum at idle there, so it should not lean it out.
I had just checked all my hoses for leaks when I changed the TPS & IAC
I'm trying to fix a high idle.

Pat

 

Go back to the DIY KOEO link, and check the base idle reset link and do the procedure...... that code 13 needs to be solved, along with the lean codes (41/91).

 

I removed and cleaned the EGR, IAC, and the TB, I reset the base idle to 750-800 in "N" (auto), cleared the codes, it is running real good right now, I will see when I drive to work tomorrow and back (about 38 miles), I'm going to read the codes again this weekend.

Pat