993 3.6 guys...how do you adjust idle?, I want to raise the idle speed on my 3.6 Options

[nine14cats]

My track car with the 3.6 in it idles around 750-800 RPM when warm. I want to raise the idle to 1000 to 1200 RPM to make engaging the 4 puck clutch/lightweight flywheel easier and also to take care of a harmonic reasonance with the car itself. There are several aluminum panels fabricated in the interior that just rattle like hell at the lower RPM's. You raise the RPM's over 1000 and it's nice and quiet in the cabin. (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

On the motor end there is a pin on the throttle lever but no provision for "tightening" or "shortening" the throttle cable, just a fitting at the end that doesn't adjust. Do I take up the slack on the gas pedal end to change idle speed? Or do I make some homemade circlips to shim the engine end of the cable?

I don't see any other idle adjustment screw on any part of the motor.

Thanks,

Bill P.

[DonTraver]

If I remember right the idle is set by the chip in the DME, to access it you need the Bosch Hammer, I've seen them go for about $2k on ebay. If you have the lightweight flywheel, you might have to get a new chip burned. They go for a couple of hundred.

The 964, 993, 996, etc engines controls are all electronic, not much you can do at home. I'm not sure about the carb'd 3.6 engines, probably need to remap the DME chip for them.

On my 3.6 RSA, I just take it to the shop, there just isn't anything I can do at home with any of it. Stock idle is 800-850, no way can I change that with a mechanical adjustment.

Good Luck, Don

[nine14cats]

Thanks Don,

It looked like there wasn't much adjustment. Unfortunately, in the race class I plan on participating in, we are not allowed to touch the factory chip at all, absolutely no mods.

I will fabricate a simple shim from what I can see.

The wonders of computers.... (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

Bill P.

[Series9]

You would have the reprogram the chip.

[East coaster]

how 'bout fakin' it into thinking the A/C is on, doesn't that bump up the r's?? Your 993 engine was setup for A/C, prolly just have to ground or tie up a line to the DME.

Just a guess, mine's not running yet! (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[Flat VW]

QUOTE (East coaster @ Dec 18 2005, 04:44 PM)

how 'bout fakin' it into thinking the A/C is on, doesn't that bump up the r's?? Your 993 engine was setup for A/C, prolly just have to ground or tie up a line to the DME. Just a guess, mine's not running yet!  :confused:

resourceful,




John

[Tom Perso]

Yup, I agree with the A/C compressor set to "ON". That should put you to 1K RPM.

(IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

Tom

[fiid]

nice idea!!

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[nine14cats]

Very nice...I'll have to take a look at the harness....

Thanks,

Bill P.

[Series9]

QUOTE (East coaster @ Dec 18 2005, 05:44 PM)

how 'bout fakin' it into thinking the A/C is on, doesn't that bump up the r's?? Your 993 engine was setup for A/C, prolly just have to ground or tie up a line to the DME. Just a guess, mine's not running yet! (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

He's right. That should help.

[MattR]

Here are some thoughts:

1) small vaccum leak. 993s are notorious for having a puncture in the vaccum lines that cause nagging idle problems. To check this, break out the starter fluid and start spryaing. If you hear the idle go up, locate the leak, and fix it. It could also be after a check valve or something. Give it a visual, and if nothing comes up, break out the vaccum gauge and get dirty. It will take a little while...

2) idle stabilizer. Those also get jammed up. Try whacking it with a wrench, revving the engine, and seeing if that helps once it settles. Sometimes when they are on their way our, that helps.

3) You could try plugging into a PST computer and see if any errors come up.

4) Did you try putting the old flywheel on to see if that changed things?

Please, i repeat PLEASE do NOT just tighten up the throttle cable. That is NOT the proper way to fix this. Especially being a track car, that is just a band aid.

PS: If your throttle cable isnt adjustable, its broken. Theres no such thing as a "non adjustable" throttle cable. You have to have one (not all cables are created equal). Check at the pedal.

[nine14cats]

Hi Matt,

Thanks for the advice, but actually there is nothing wrong with the engine or throttle cables. The motor runs perfect. I just want a higher idle speed for my preference, not the factory idle. With a regular clutch plate or the lightweight unit, it idles below 1K RPM. I want it at ~1200 RPM. As it comes from the factory, the motor is smooth and purrrrrssss like a kitten! (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

I was looking at the motor last night and there appears to be an adjustment screw on the throttle body itself.

Can I use this adjustment screw to play with idle?

Thanks,

Bill P.

[MattR]

I'm a little confused. Is this a track car? If so, have you heard track cars idle? The 996 cup cars couldnt hold an idle if their life depended on it and thats a factory porsche race car.

First, your idle will be messed up with a light flywheel. If you care about idle, stay with the stock flywheel. All the harmonics are setup for that flywheel. Thats what happens when you go from a 30 lb flywheel to a 12 lb flywheel and keep everything else the same.

My opinion: either accept the low idle, change your flywheel, or build your engine /dme to your new harmonics (which isnt an option in your case). If you're making a track car, you wont be idling much anyways.

[TimT]

QUOTE

The 996 cup cars couldnt hold an idle if their life depended on it and thats a factory porsche race car.

(IMG:http://www.914world.com/bbs2/html/emoticons/WTF.gif)

Factory GT3s had been shipping with Tilton clutches, and lightweight flywheels for awhile.. and they will idle all day long and 900-1000 rpm. The GT3RS'sss we maintain star and idle fine.. with even the carbon Tilton flywheels.

Giving a false a/c request will bump the idle.

[MattR]

Last thursday at willow springs it was about 32 degrees at 7am. Our 997 cup car had to be revved like hell to go from the cold side of the pits to fuel lane to stay running. It quit about 3 times in 100 yards. This is a newish motor directly from Motorsports with the Grand am/alms seal and everything.

Even when its fully warmed up it hunts for idle. It doesnt have a constant street car idle. All of our 4 cup cars do the same thing...

[nine14cats]

Given today's technology and the fact that several members here and at Pelican build cars, I don't believe I have to settle for anything.

I want to keep my light flywheel, I want to keep my 3.6 with the stock DME programming to stay in class, and I want the car to idle at 1100 RPM. Several folks have given me ideas on how to raise the idle RPM by 300. In fact, JWE will make a mechanical add on that will keep the RPM at 1100 if I want.

I'm just grateful for the advice and the ideas. It's fun to make it work.

In fact, I've already talked with a chip company that will burn a new idle map in a chip...but again, I want to follow the letter of the rules and not touch the box.

The current motor idles fine. It doesn't die in hard braking. There is nothing wrong with the car other than at ~800 RPM the aluminum panels rattle in the car and the G50 whirs a little. I'd like that gone.

I have confidence I'll have a higher idling machine that's comfortable to sit on grid. (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

Bill P.

[TimT]

Billl, you dont need a new chip. Your ecu can be reflashed with new idle charecteristics.

but if the car idles OK wouldnt it be easier on the wallet to learn new launch methods?

[TimT]

QUOTE

the G50 whirs a little.

if you want that gone reinstall the dual mass flywheel (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

[nine14cats]

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

I'm a raving wimp! The car launches fine for me, just a little touchy but I'm used to it already. My wife will get used to it too, she's a good shoe. If I sit in the car I can just stab the gas a little and we're up to 1100 RPM and the car doesn't rattle.

I will make it smooth. Because I deserve it for the amount of money I've spent on my toy!

Bill P.