North American Turbocoupe Organization



IAC differences?.....
Kuch Offline
Senior Member
#1
I am looking to replace my IAC on my 88 to see if it fixes a random high idle issue I have been having. My question is, what makes the IAC for 87-88 2.3T's different from other Ford products of the 80's? The part number for ours, Standard Parts AC29, says only 87-88 2.3's. These seem to be simple electro magnet controlled valves, as they all have the same bolt pattern and plugs, what makes them different for ours? Can't I just run one from an 88 5.0 Mustang for $35 instead of the TC specific one for $95? What gives?
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4, ported E6, 255LPH, Kirban, Stinger Exhaust, MGW shifter, K&N, Gillis valve, BP1.5, PIMPx, Koni's
1964 Ford Galaxie 500XL, 390 6V, Big Solid cam, Headers,3.89's, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 312 4bbl intake, headers, 3 Speed, slow and low
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spittinfire Offline
Member
#2
I don't know the specific differences but I do know that I took an IAC off a 5.0 and put it on a 4.0 V6 without issue.  I think a lot of the differences have to do with the configuration of the assembly such as plug location/orientation.  The only other thing I could think of would be the sensitivity of the valve.  If you have a 5.0 IAC laying around I would throw it on there and see what happens. 
I can test this theory if you don't mind waiting for a couple week until I get back to my dad's shop.  I'm 95% sure he's got a couple of 5.0 IACs laying around.
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Mikey97D Offline
Member
#3
The TPS has a different voltage range than the 5.0 version so perhaps that is the reason?

Is the engine temperature (the sensor in the intake manifold) reading correctly? I would think you can monitor that through the PIMPX? Or have you already gone that route and it is definitely the IAC?
1988 TC, 5 spd, Stinger 3" Exhaust, Schneider Roller Cam, -4° Cam Pulley, Cone Filter, Gilles Boost Control Valve set at 17 psi, Walbro 255 lph, CHE Rear Lower and Upper Control Arms, Braided Brake Lines, Hawk HPS 5.0 Front and HPS (F) Rear, CRES Inserts in front calipers, and '93 Cobra Wheels with General 235/50R17 Tires.   
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Kuch Offline
Senior Member
#4
at idle the 5.0 TPS is supposed to be adjusted to .94, so the same as our 2.3's, not sure why there is a difference on the IAC's though. A bad IAC will typically result in a hanging high idle or erratic idle, which mine does have. I have been running a junkyard genuine Ford 5.0 IAC for years, but it has been acting up lately, so I might just buy the 2.3 specific IAC and swap it in the spring, still not sure why they have different part numbers and a huge increase in price. Maybe law of supply and demand at play here?
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4, ported E6, 255LPH, Kirban, Stinger Exhaust, MGW shifter, K&N, Gillis valve, BP1.5, PIMPx, Koni's
1964 Ford Galaxie 500XL, 390 6V, Big Solid cam, Headers,3.89's, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 312 4bbl intake, headers, 3 Speed, slow and low
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Chas K 88 Offline
Member
#5
Kuch, I had random high idle issue with mine where it would be idling fine and then shoot up to 2000 RPM and stay there. It sometimes would cycle up & down and was rather embarrassing at stop lights etc. After installing the PiMPx I was having a hard time tuning the idle and I noticed the TPS was jumping from 0 to 15-20% while it was idling. I had another TPS handy so I swapped them and the problem went away. I think that may have been the cause of my high idle issue before the upgrade, you may want to look there.

PS I had the same issue in the late 80's early 90's with an 87 Mustang GT. I ended up trading it for a new 91 Eagle Talon AWD turbo 5 speed. That was a fun car, the wife still isn't happy that we sold it.
Chas K
Current setup - 88 T-bird, 5 speed, vacuum assist master cylinder, T3/T4 50 trim turbo from Bo-port, oil feed & return lines, 3” turbo down elbow, 3" to 2.5" dual exhaust and PiMPx from Stinger 255LPH fuel pump, CD, trip-minder, RR , K&N, 140 MPH speedo conversion (thanks Jeff K).
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Kuch Offline
Senior Member
#6
Thanks Chas, yeah I should look at the TPS as well on mine in the spring, as it is all set up for winter storage right now. It's got to be one of those two items, TPS or IAC. Your right, those Eagle Talon turbo's were fast cars along with the Eclipse AWD turbo's, don't see many of those around anymore either
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4, ported E6, 255LPH, Kirban, Stinger Exhaust, MGW shifter, K&N, Gillis valve, BP1.5, PIMPx, Koni's
1964 Ford Galaxie 500XL, 390 6V, Big Solid cam, Headers,3.89's, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 312 4bbl intake, headers, 3 Speed, slow and low
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