1G IAC ISC Control 2024, Any Aftermarket Bolt On For S90?

[Car Cannibal]

My ported stock TB by Steve Monroe (retired in 2023) has a rough spot that the blade hung up in so I swapped to the S90 74mm TB. I want to go back to the IAC/ISC control but nothing appears to bolt onto the bottom of this like the factory.

Magnus makes a remote it looks like for the 90mm and uses the factory ISC but these sensors are now $350 etc.

Anyone have options for the S90?

Anyone make a bolt on but that accepts a different IAC/ISC?

GM or Honda etc would be way cheaper and easier to get at parts stores. I'm thinking if nothing pops up I'll get one made via a CNC friend.

 

[1cleangsx]

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You can bolt on the isc/fiav from a 91-94 throttle body, I just did this with my 70mm s90

 

[Drewpy Dawg]

If you're not dead set on using an OEM IAC, Standard Ignition part number AC146 is $56 from Rock Auto. I have a good OEM unit but picked up one of these anyway, just to have a spare for the future.

 

[1cleangsx]

That’s good to know!

 

[Stapl3]

https://www.dsmtuners.com/threads/how-to-add-a-dsm-iac-to-any-aftermarket-throttle-body.448261/

 

[Car Cannibal]

Thanks for the replies...

1cleangsx, awesome, I didn't know the factory bolts up to it. I didn't read the small print and since there wasn't a picture of it on as an option I just figured it was another aftermarket make it work part.

Drewpy Dawg, great link, way more affordable and it bolts on and the plug end fits.

Stapl3, thanks, I did see that but even Volk said it wasn't great so I'm gonna pass on that mod and I like the idea of it bolting onto the TB for space etc.

Does anyone know if the 1990 turbo Throttlebody FIAV ISC bottom section bolts on?
These seem to be more available and cheap.

 

[1cleangsx]

The 1990 throttle body is one solid unit unfortunately, hence the reason I sourced a 91-94 unit

 

[DSMPT]

Does anyone know if the 1990 turbo Throttlebody FIAV ISC bottom section bolts on?
These seem to be more available and cheap.

The 90 bottom part is totally different from the 91+. If the 91+ bottom part is direct bolt-on to the S90, also the bottom part of EVO 1/2/3, Galant, RVR/Chariot, 3000GT/Stealth and more should fit.

 

[Car Cannibal]

Thanks, another 1990 only unique part huh.

I'll try to hunt down a lower section or get one made in Aluminum so it looks like the S90 is complete.

 

[m1nd64m3]

I just came across this part from a 3000gt site this afternoon and picked one up myself, might be exactly what you need.

3000gt/Stealth/DSM Billet Throttle Body Fast Idle Air Valve (FIAV) Delete — Craftworks Industries

Machined in 6061 billet aluminum, this is a complete replacement for the fiav/iac assembly below the throttle body. Easily remove the intake manifold without having to deal with messy coolant lines. If your fiav is not working, it can cause idle issues. All hardware is included. Replacement gaskets

www.craftworks.industries

 

[Car Cannibal]

That's it thanks, just got 1, we'll report back after install.

 

[Car Cannibal]

Ok now I just noticed my FIAV oring like gasket didn't look like it'll work with that thing.

Is there a flat gasket part number for us or will our oring FIAV gasket work with that?

I'll look for flat gaskets again.

This is the ISC gasket

RockAuto | All The Parts Your Car Will Ever Need

Auto Parts for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

 

[m1nd64m3]

I’m sure you could seal it with a thin layer of rtv between the parts.

 

[Car Cannibal]

Mitsubishi FIAV (Fast Idle Air Valve) O-Ring Seal - 91-99 DSM / 3000GT / Stealth

Genuine OEM Mitsubishi FIAV (Fast Idle Air Valve) O-Ring Seal fits all 1991-1999 1G & 2G DSM Eclipse GST/GSX, Talon TSi & Laser Turbo, 3000GT and Dodge Stealth TT and N/T models. Ships worldwide. Buy yours at STM!

stmtuned.com

Above is the FIAV oring gasket

 

[m1nd64m3]

It’s two machined surfaces, ditch the o-ring gasket and make your own gasket or just use rtv.

 

[Car Cannibal]

Not off to a great start...
OHM harness is 4" short, can't connect the connector. This harness has been horrendous with issues that cost me so much time and money.

Then to make things better...
Swapped in ISC bracket, used oring for lower bracket, idle on start up now at 2600rpm. Turned the idle screw 100% out and it's like 2000rpm so there's a massive leak, before was 900rpm. Sprayed around sensor and bracket and don't see anything but I can't get to all areas to confirm. I suspect middle bolt is leaking air past it but damn can't catch a break here in this restoration on the easy stuff even.

I'll return with the solution.

 

[We're on Boost]

OHM harness is 4" short, can't connect the connector.

Was the harness made for a 1990 model year? If so, it could be about that much too short there, because the original 1990 ISCs had their own short harness coming out of them, about that long or a little more. Take a look at my pic in post #5 here. Then in post #6 you can see how I extended the 6 wires on the main harness, which is a 1990 harness in a 1990 car. Then it was fine to reach a regular STANDARD MOTOR PRODUCTS AC146.

 

[Car Cannibal]

I must have a big air leak, even after the Haltech tuner came in, no ISC control. With the TB screw it still nothing etc, got Felpro make your gasket to try that next. Damn cars been a real mess the whole year, it's worse now after $30k then ever before.