Spyder 4G64 IAC Replacement

[Clawless]

Hi everyone,

Here's some background info: I need to remove my IAC for cleaning or possibly replacing. I've gotten a CEL for the IAC and also MAF sensor. In the morning, the car idles high (2k RPM), I drive it and the idle goes to normal if I turn the key off and on again. When I leave work in the afternoon, the car can't hold at idle. It won't even try to maintain idle and just dies. I just ruined my starter by dealing with the constant on/off in traffic since the car won't idle.

Now my issue: Does anyone know the easiest way to remove the IAC on a 4G64? I took off the intake piping and can't really see where the IAC bolts to the throttle body. Is it posisble to remove the IAC from the engine bay or do I have to reach from under the car? I appreciate any help, thanks!

 

[DogWhistle]

Your IAC can truly only properly be accessed by removing the throttle body from the car. With the front cross member in the way, it would be nearly impossible to service from underneath.

To remove the throttle body, disconnect and remove the intake ducting, unplug the electrical connections for the ICS and the IAC, and disconnect and stopper the coolant tubes leading to the throttle body.

Loosen the bolts holding the throttle cable to the intake manifold, and then remove the four nuts holding the throttle body to the intake manifold. When the throttle body slides off of the four mounting studs, you’ll be able to flip it over to disconnect the throttle cable.

Now you have full access to the throttle body components including the IAC.

 

[Clawless]

Your IAC can truly only properly be accessed by removing the throttle body from the car. With the front cross member in the way, it would be nearly impossible to service from underneath.

To remove the throttle body, disconnect and remove the intake ducting, unplug the electrical connections for the ICS and the IAC, and disconnect and stopper the coolant tubes leading to the throttle body.

Loosen the bolts holding the throttle cable to the intake manifold, and then remove the four nuts holding the throttle body to the intake manifold. When the throttle body slides off of the four mounting studs, you’ll be able to flip it over to disconnect the throttle cable.

Now you have full access to the throttle body components including the IAC.

Thank you for the detailed reply! While I have the throttle body and IAC off, would I also have good access to replace the starter?

 

[mjm0157]

IAC is easy to get to, just take the throttle body out.
But you likely have other issues to deal with.

When I got my 4g64 Spyder I had idle issues and bogging issues.
Before pulling throttle body do a “ boost leak test” on throttle body. Hook up boost leak tester to throttle body inlet and pressurize. Spray soapy water on components that contain metered air and you will find leaks.

Places I found Vac leaks are:
PCV valve
PCV grommet
Fuel injector donuts- dry rotted and cracked
Throttle body shaft seals

Recommend rebuilding throttle body and doing FIAV bypass
Get new IAC and IAC o-ring

If your feeling frisky do EGR bypass as well.

As for the random bogging issue I had, there is a secondary fuel relay on drivers side of center console. It varies voltage to fuel pump to gain fuel economy, I believe the only DSM to receive this secondary relay is the 1999 Spyder GS 4g64. These relays go bad and act crazy. It will decide to drop pump voltage when at the worst time, like when you're pulling out into traffic.

Recommend bypassing asap!!

I always get to starter from below. You can squeeze it between engine and sub frame

 

[DogWhistle]

Here’s the link to what @mjm0157 is talking about:

Spyder - 4G64 Spyder GS Fuel Pump Relay Module Bypass

Disclaimer: This documents mods made by me. I make no claims about any mods you make on your car that follows my process.Hours were spent trying to trace the cause of our performance problems on our 1999 4G64 Spyder GS. The car would run great, switching from open loop to closed loop, until...

www.dsmtuners.com

 

[mjm0157]

Just thought id point out the relay because it was the cause of alot of headaches!

 

[Clawless]

Thanks guys! I'll let you guys know what I find this weekend.