My TPI is driving me crazy....er.

[40_Tudor]

87 IROC TPI I installed in my 40 Tudor started idling at 2k last week. No codes, no pending codes, numbers on analyzer within specs.
Cold start, fast idle for a couple of seconds then it idles down to ~ 700 rpm. Let it worm up shut if off and restart it goes to 2K. No vacuum leaks, except Idle Air Control fast idle passage. You can hear fast idle vacuum from throttle body just like cold start.
TPS set to 0.58v.
Jump ALDL to extend IAC pental, disconnect plug and remove IAC valve, measures 1" shoulder to end of pental, (should be ~1 1/8 to 1 1/4").
I have 5v to Coolant Temp Sensor.
Replaced old 1227730 ECM with rebuilt NAPA unit, no change.
IAC, TPS, CTS new this spring.
As I said no codes, numbers within specs on analyzer.
Double checked all grounds.
Something is telling the IAC to retract. It's driving me crazier than I already am, if possible.
Anyone got any suggestion?
I'm loosing cruising time, only so much allotted for summer in Columbus.

[Crosley.In.AZ]

faulty IAC motor?

something telling the ECM to fast idle after warm up?  temp sensor out of spec , yet scanner shows it good??

[UGLY OLDS]

I agree with Tony....also check the resistance on the CTS  when cold & after warm up.........

[tomslik]

might wanna look at the t'stat.
should be 195....
any less and the 'puter thinks it's cold outside....
sounds like the iac is working,they generally either work or not...

[Crosley.In.AZ]

might wanna look at the t'stat.
should be 195....
any less and the 'puter thinks it's cold outside....
sounds like the iac is working,they generally either work or not...

that is true , but why  is the ECM commanding a 2k idle RPM?

[40_Tudor]

ECM is reading idle RPM at 068 x 10 on OTC scanner after worm up but it runs 2K.
I put an ohm meeter on the CTS after it was warm, I'm going to go recheck it cold and restart and check it again.
I've got a printout of pin voltages from Mitchels. It says 1.3 KOEO and 1.4 KOER. I didn't print out the page that says where to take the reading, I assume it at the ECM plug yellow wire. I have 5v at the CTS plug at the block.
This is going to be something really stupid I keep overlooking.
One of those flat forehead moments.
I'm getting a flat forehead from banging my head on the fat fender. I'm loosening ether way.
Just taking a chance someone else has solved this problem and maybe save me some frustrations.

[Bruce Dorsi]

I never worked on a TPI system, so I am not familiar with them.

Is there an EGR valve on this application?  .....If so, is it hanging open?

[Crosley.In.AZ]

OK.... if I understand this:

the scanner shows the RPM at 680 , but the engine is actually near 2k RPMs?

sure sounds like bad information to the ECM..... a sensor that goes wacky when it is warmed up?

[enjenjo]

What happens to the RPM when you put it in gear? If it becomes normal, check the ground at the shifter position sensor on the neutral switch.

[40_Tudor]

Here's an update.
I jumped the ALDL with the key on to extend the Idle Air Control Valve, Unplugged it and removed it. It should measure 1 1/8" to end of pental. It only measures 1". Makes for a BIG vacum leak.
I dug out the old IAC and plugged it in with the ALDL jumped. It screwed out like it should. No I can't use it because the threaded part is cracked. Anyway I digress,  I held the new ALC valve in my hand and plugged it in. It made a little noise but wouldn't move unless I pushed in on the pintal. This sucker is going back to NAPA in the morning.
When the new electronic stuff works its great but when it screws up its a royal pain.