2G 1997 Eagle Talon TSI AWD High idle.

[Classifiedcalli17]

Okay okay! so I know this has probably been gone through, and answered at this point millions of times haha.. Anyways, I have a 97Talon TSi AWD with 65k miles. The car was purchased bone stock, since then I have added..

Full 3" turboback exhaust (Megan racing DP, and HKS catback)
Injen Intake.
Greddy upper/lower hard pipe kit using the stock SMIC, and a turbosmart BOV (Recirculated)

So, the entire system has been boost leak tested and it's sealed. I started with a horrendous idle surging issue after the mods added listed above, smoking from exhaust, running insane rich! come to find out it was a full tooth off on timing.

Since then I bought a complete OEM Mitsubishi timing belt kit from STM. All new pulleys/tensioners/Water pump/belts etc. Installed everything with a friend who knows his stuff when it comes to these cars. Fired the car up, and it runs amazing but the idle is high. It seems that when I first fire up the car it idles/hovers around 1200RPM, and then after taken out on the road, and driven a little bit it creeps up to 1500RPM, then closer to 2000RPM.

It's never had any kind of idle issue before except for when it was off timing of course but that was surging and at lower idle like 1000rpm, and below. The car has ZERO codes, and does not throw a check engine light. Like stated the car runs fantastic, boosts great, feels very smooth and powerful, compression was also checked and damn near perfect numbers, all within spec since ownership. Before modding I did quite a bit of maintenance for peace of mind. Both O2 sensors replaced with Denso ones, Brand new NGK plug wires, and plugs, Brand new OEM Mitsubishi fuel filter, OEM PCV valve, VC gasket, the list goes on.

Any help/input would be awesome! I know it's hard to diagnose a car without hearing/seeing it. The car sounds insanely healthy, motor is quiet, and runs as it should minus the high idle.

Any info on what to check/look for? Thanks guys!

 

[Dericsh]

Have you tested the ISC?

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[chrisman287]

I would check TPS voltage also

 

[ErikTande]

If it idles ok when it's cold, but gets way high when it's warmed up, then your throttle cable is probably too tight. Adjust it when the car is running and warmed up.

I just had this same problem with my 97 talon, same color and everything

this was literally me:

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[steve]

^ That was my first thought after reading his post.

 

[pokeytsi]

Couldn't hurt to check the ecu and make sure there's no damage since you had idle surge issues initially.

 

[Classifiedcalli17]

***UPDATE***

So my buddy, and I removed the throttle body, Cleaned it out properly, installed a new BISS screw, and O-Ring, After we re-installed the throttle body, The screw near the throttle cable was turned in a bit too much, we loosened that up a bit, with car running made small adjustments to the BISS screw until we got the idle to be right around 850rpm. idles smooth, and clean. Have not taken it out on the road yet to do some normal driving (IT WILL NOT STOP RAINING HERE) XD Everything sounds good, and it idles smooth, the only thing i have happening now is when i rev it up a decent bit, it BOGS way down almost to the point of dying, and then kicks itself back up to the 850rpm mark and returns to normal. Any ideas on that? I suppose i could test the TPS, and ISC. MAN i forgot how insanely finicky these cars are .. Thanks for the responses guys! Just trying to get her back to where she needs to be.

 

[chrysler kid]

if you unhook the battery terminals and do a hard reset on the ecu calibrations it will go back to factory settings

So if you fixed a problem the car could still be making adjustments for fueling with the ecu assuming the problem persists even though you fixed the problem

Long story short it should get better on its own. If you unhook the battery terminals and it resets the ecu and the car still has a problem finding a good idle, most likely there is still a vacuum leak. As mentioned though be sure to press the throttle body down to make sure the throttle cable isnt getting stuck or the throttle body is sticking open causing the proble

I typically do boost leak testing from the intake manifold, pressurizing the intake manifold to the turbo, as opposed to pressurizing the turbo to the manifold. Typically for me vacuum leaks happen after the throttle body in the intake manifold though so thats where I start