Having an idle problem

freyguy_412 · Post by **freyguy_412** » July 13th, 2005, 8:30 pm

Hey, from research I've done so far I think I know what I got to try, but I wanted to give the whole situation and see what people thought.

When it's cold out side, and I put my foot on the brake pedal, my RS starts surging from idle speed to about 1500 rpm's. When I let go of the pedal, the car will jump up to 1500 and slowly think about coming down. I'm betting the TPS cleaning procedure (Tunes67 thank you for an awesome write up) is needed, BUT here are the extra circumstances.

I just performed the throttle body coolant line modification. While I was doing that, I took out that resenator that goes before the ISC valve, and just hooked up the shorter hose to that port. I've tried hitting all the connections with a flammable silicone aerosol (no WD40 at the time) and didn't get any wierd surges. When it's warm outside, the car idles great, but at night or in any cool weather, it's getting tempermental. Is cleaning the TB the least of my concerns?

jimishadow · Post by **jimishadow** » July 13th, 2005, 8:44 pm

chec your brake power booster, plug vacuum hose and see if it goes away

Tunes67 · Post by **Tunes67** » July 13th, 2005, 9:53 pm

No sweat on the write up man.. and your issue does sound like a sticking IAC valve.. However.. I am not familar with this..

I just performed the throttle body coolant line modification. While I was doing that, I took out that resenator that goes before the ISC valve, and just hooked up the shorter hose to that port

And it does seem a bit weird that your problems started after doing this.. whats the idea behind this mod? And just for reference sake.. the job of the IAC valve is basically the same as a "Choke" on a carburated car.. its just computer controlled. It works in conjunction with your coolant temp sensor and ECU to determine how much air to allow through to control your idle speed during warm up. Cheers

Tunes67

freyguy_412 · Post by **freyguy_412** » July 14th, 2005, 3:32 am

.. However.. I am not familar with this..

Quote:
I just performed the throttle body coolant line modification. While I was doing that, I took out that resenator that goes before the ISC valve, and just hooked up the shorter hose to that port

The coolant line modification I found on here somewhere. It is supposed to help keep the air entering the tb cooler, since those lines are only pumping hot water up there anyway. The resenator was between my ISC valve and the air intake tube. I figured resenators are bad everywhere else, and figured this one should go away too.

To check the brake power booster, I just remove that large hose going to the intake manifold and plug the ports I assume? Do I drive the car with out the power brakes to test this theory? Thanks for the help so far.

Chino921 · Post by **Chino921** » July 14th, 2005, 8:42 am

The fastest way to diagnose a bad brake booster is to let the car idle and spray it down with starting fluid. If there is a leak, then the motor will rev up.