Idle problem with 3.6 engine

[mmasse]

I have a problem with the idle on my 993 Euro Vario '97 engine.

Once the car warms up the idle is too high. Around 1200 RPM.

I have a light flywheel and Cintex chip (provided with Timmins kit). following Bill's Verburg recommendation on other posts, I tried to adjust idle with the ISV. The problem is that if I adjust the ISV to idle at 900RPM when the engine is warm. It won't start when cold.

I also read on other threads that it could be a problem with a loss of vacuum. I connected a vacuum gauge to the system and got 15cmHq (steady) when idling. Is this ok?

Any other suggestion?

Thanks in advance

[Bill Verburg]

You might try looking for intake leaks

[mmasse]

Thanks Bill

How do I do that? Where should I look? Sorry but noe idea where to start!

[Bill Verburg]

Smoke-look for a stream, ether- look for increased idle speed

[mmasse]

Sorry, Bill I am slow today... but could you give more details.

You mean to shoot smoke around the intake and then look for the stream. If so, what do you use to produce smoke?

[bigchillcar]

don't use carb cleaner, but buy some brake cleaner and pray around your intake area and listen for the sound of the engine rpm increasing...that would indicate a leak. brake cleaner is more volatile then air, so you'd expect an increase.
ryan

[bigchillcar]

actually, i have an intake leak on my 964..i can hear the hiss, but i'm actually new to the 964 and having my troubles isolating it. anyone have suggestions as tot he most common sources of intake leaks on these cars?

[herman maire]

Maybe your chip is faulty....

[mmasse]

I will try the intake and if not I will insist with Timmins to get an exchange. I suggested a while a ago that it could be a problem with the chip but he was not very keen to exchange it.

Initially, I thought it could be the ISV, but not... I am running out of options. Car is running great otherwise but the idle issue is quite anoying.

[Joe Bob]

High idle could be the microswitch at the throttle body. Hunting idle is indication of a vacuum leak.

[mmasse]

Is the microswitch accesible? any pics of where it is located and how it looks like? What could be the problem with it?

Thanks a lot for your help

[dfink]

I would start over looking for vacuum leaks. You dont need any smoke or cleaner to find many leak. I am in the same process right now. When you have just a few small leaks you can adjust the idle where you want it either hot or cold but then the ISV can't overcome the changes either way. So if you screw adjuster in to far the car won't idle when cold if too far out the idle hunts.

I don't have pictures but...

hose adapter from PVC valve to oil tank. (crack)

Hose adapter from brass to plastic fitting on brake booster.

little plastic hoses come loose from fuel pressure regulators

Cracking on the intake boot itself or loose connections to the intake boot

Check that the vacuum line is on top of the control valve just before the PVC valve.

The small loop vacuum line that goes from throttle body to thermo switch can crack.

Make sure that when adjusting the idle the car is warm and that the test port is jumpered and the 02 sensor is disconnected. That should center the ISV so it can adjust both hot and cold.

If still not working after that then start in with the brake cleaner to look for intake leaks.

[mmasse]

Thnka dfink.

Could you please give me more details on:

"Make sure that when adjusting the idle the car is warm and that the test port is jumpered and the 02 sensor is disconnected. That should center the ISV so it can adjust both hot and cold"

Where is the test port you are refering to, on my 3.6 engine?

[Joe Bob]

The microswitch is depressed by the throttle body arm when at idle. The switch could be faulty or gummed up or out of alignment.

BTW, there are many engine diagrams on CD that you can get with exploded diagrams that will help.

[mmasse]

I looked for intake leaks with both propane and starting spray. I was not able to detect any change in idle. I sprayed it on every inteake boot, and every vacuum line I was able to see...and nothing.

I will try ti check the throthle swith, but I am not sure if I can access it with the engine on the car...no way I will t ake the engine out for this!!

[Joe Bob]

It's on the trottle arm where the cable or rod pulls on the throttle body....there's a tiny "micro" switch where it rests at idle. Ya can't miss it.

[mmasse]

I keep having trouble tracking this problem. I kind of ruled out vacuum leaks after thourough search with propane and starting fluid.

I was not able to find the microswitch though. Do you have a part number so I can check PET for where is it install?

Is this the microswitch?

Throttle Switch, 911 Carrera 2/4 (1995-98), 911 Turbo (1995-98), Each

[shahram]

Mario, I had the same problem last year. I also used Timmins Kit with Cintex Chip. The chip was faulty. Timmins offered exchange. So I sent him back the chip and installed the stock chip.
The amazing thing is that I don't have Idle problem any more with the stock chip and didn't go back to cintex chip any more.
Add. problem with Cintex chip was that the revision limiter was set up on 6100 rpm. Timmins said that was a bad lot of cintex chip.

[mmasse]

i will try with Steve.

I do have the stock chip. So, i guess I will try to exchange it and see if it works better.Btw, what's the advantage of Cyntex chip vs stock?

[shahram]

Well, the Cintex Chip suppose to reduce the staling issue when you combine 915 with 3,6. at the same time it should get you up to 15 more hp. But to be honest, I didn't recognize anything, but that could be because of the faulty chip.
I will try a Steve Wong chip soon: http://www.911chips.com/
Received good feedbacks about this chip on Rennlist.