North American Turbocoupe Organization



Trying to hunt down an iac for 88 tbird
88turbobird5 Offline
Junior Member
#1
Is their an iac i can use off of something else or a part number for an 88 tbird and has anyone seen an iac cause a high idle
88 T-bird stinger fmic/cold air intake/t3t4/stinger oil feed line/3 inch full exhaust to dauls/super coupe throttle body
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Pete D Offline
Administrator
#2
Have you cleaned it out good. They can get carboned up and then parts stick. Take the solinoid off and clean out the valve mechanism on he other end w/ carb, brake cleaner. Put a little oil on the valve shaft, test for problem resolution.
Pete Dunham


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88turbobird5 Offline
Junior Member
#3
Yea i took it apart cleaned it out the best i could its got a high idle at around 1500 rpm i was going after the tps sensor at first set that back in range and tested it no jumps or anything weird on the volt meter i also sprayed it down with ether on vacum connections and intake and intercooler set up just having a real hard time hunting this down and going threw it with a fine comb this thing is really kicking my butt
88 T-bird stinger fmic/cold air intake/t3t4/stinger oil feed line/3 inch full exhaust to dauls/super coupe throttle body
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88turbobird5 Offline
Junior Member
#4
I also did some steaching here on the site to find people that had similar probloms or as close to mine situation as possible and check into the things that said worked for them with no luck was also looking to see how to ohm the iac out if that would benefit in any way
88 T-bird stinger fmic/cold air intake/t3t4/stinger oil feed line/3 inch full exhaust to dauls/super coupe throttle body
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Mikey97D Offline
Junior Member
#5
Following along and thank you for updating as you go. I need to do the same as my idle fluctuates a lot too.
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Jeff K Offline
Administrator
#6
Check closed throttle TPS voltage. If over 1.0 V you will get high idle. Set closed throttle TPS to .9V.

What happens if you unplug IAC electrical connectorwith engine running? Idle should drop to 750-800 RPM and engine may run rough and possibly stall. If engine stalls base idle is set too low. If this happens, issue is not the IAC.

Is the current IAC a Motorcraft or cheap parts store junk. The ONLY IAC's that work correctly are the Motorcraft ones.

Have you checked for vac leaks?

If kept clean and lubed (drop of oil on the shaft going into the solenoid coil) IAC should outlast the rest of the car. There isnt much inside it to fail.

All my Fords have their original IAC's with close to 600,000 miles total between them.

Have you checked for vac leaks?
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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88turbobird5 Offline
Junior Member
#7
(05-29-2019, 09:53 PM)Jeff K Wrote: Check closed throttle TPS voltage. If over 1.0 V you will get high idle. Set closed throttle TPS to .9V.

What happens if you unplug IAC electrical connectorwith engine running? Idle should drop to 750-800 RPM and engine may run rough and possibly stall. If engine stalls base idle is set too low. If this happens, issue is not the IAC.

Is the current IAC a Motorcraft or cheap parts store junk. The ONLY IAC's that work correctly are the Motorcraft ones.

Have you checked for vac leaks?

If kept clean and lubed (drop of oil on the shaft going into the solenoid coil) IAC should outlast the rest of the car. There isnt much inside it to fail.

All my Fords have their original IAC's with close to 600,000 miles total between them.

Have you checked for vac leaks?
It is an orignal motorcaft iac. So i follewed the guidelines here on the site on re calibrating the tps did it to the tee and set it at .94v i have sprayed down pretty much the whole engine bay from intake to turbo all vacum lines and intake bpv everything i can think of and still nothing i will try running it and unplugging the iac to see what it does
88 T-bird stinger fmic/cold air intake/t3t4/stinger oil feed line/3 inch full exhaust to dauls/super coupe throttle body
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88turbobird5 Offline
Junior Member
#8
Ok so i just went and strated it fired up idle dropped low then surged back up to 1500 rpm at idle and stayed there so i went out unplugged the iac pigtail and the car surged then drops dead did it again while trying to give it a little throttle via throttle body and it surges then dies ?
88 T-bird stinger fmic/cold air intake/t3t4/stinger oil feed line/3 inch full exhaust to dauls/super coupe throttle body
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Kuch Offline
Member
#9
(05-31-2019, 02:38 AM)88turbobird5 Wrote: Ok so i just went and strated it fired up idle dropped low then surged back up to 1500 rpm at idle and stayed there so i went out unplugged the iac pigtail and the car surged then drops dead did it again while trying to give it a little throttle via throttle body and it surges then dies ?

I know that there are different part numbers for these based on applications, but when at the junkyard I look for similar year Ford's with newer looking replacement IAC's. The last one I got was from an 88 Mustang GT with a new IAC on it. I replaced the original on my 88 TC with that one and it ran great, idled great, and never had an issue. It plugged right in and is still in it today. Maybe just find one to swap out and see. I had an older Explorer that had similar issues as yours, a different IAC fixed it
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof, T3/T4 50 trim, 255LPH, BBK AFPR, 3" DP dual 2.5", MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
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Jeff K Offline
Administrator
#10
Sounds to me like you hace a vacuum leak, not an IAC issue. The fact that the engine speed dropped / engine stalled when you unplugged the IAC connector proves that the IAC is not the issue.

Have you run the complete PCM self tests (KOEO, CM, and KOER)? Run the tests even if the CEL isnt on.

Are you sure the CEL even works? CEL should illuminate with the key in RUN, and remain illuminated until the engine is started.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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