RajDatta

My car idles fine when cold. Once it warms up and I get off gas, I notice that my idle will dip all the way to 600rpm before it recovers upto steady 1000rpm. I tested the TPS and felt that it was adjusted correctly as I would hear the "click" as soon as the throttle moved.
I ordered a new ISV and installed it this evening. Funny, the symptoms are still the same. Once the car warms up, idle drops when blipping the throttle and then it gets steady. Also I noticed that when I put AC on, I idle drops a good 150rpm as well. Should the ISV not compensating for AC?
Also, I tried playing a little with TPS and noticed that when I install the TPS in a position where I no longer hear the "click" my idle does not dip down anymore and comes down slowly like I would like it. Ofcourse all this is being done once the engine is warm.
So, my question is why is my car idling at 1000rpm now? I tried turning the throttle screw in and at this point I have almost 1/4 of a turn before it is completely shut. I just changed the O'ring seal on the throttle screw to make sure it does not leak.
Is there a problem with running the car with the TPS adjusted in a manner where I no longer get the click when off throttle? What should be my next step. I just want a steady 900-1000rpm which is neither effected by temp or AC. How can I achieve that?
Thanks.

User 41221

I don't know enough about how your car was built to do anything more than guess, but I was wondering if it doesn't have something to do with the ignition timing... what DME and chipset are you running?

Regards,

Ski

When setting the idle you need to defeat the IAS valve. I'm not sure on your car which plugs on the diagnostic port defeat it but check out this link maybe it will help..

http://www.lindseyracing.com/pics/techgara

RajDatta

The car is setup just like a 944 turbo, using the same electronics, dme/klr and wiring harness. I do have the diagnostic plug like all 944 turbo's do. It is an exact same car but has a MAF setup like most 944 turbo's upgrade to.
Raj

User 41221

Tell me more about your DME chip, then, where did you get it? I am wondering if the external switch on your DME is set properly. You car sounds kind of like an early NA with the infamous "shudder", and I know FR Wilk found a fix for that by bumping the ignition advance. Due to the nature of your car, I am wondering if its not something similar, but I really still don't know enough about your car to say.

Nice link to the banner, ski! lol Raj, he's right about bypassing the idle stabilizer when setting the idle. Go to www.lindseyracing.com and look on the left side of the page, under "Information" for the link to tech garage. There, you will find some very helpful information.

Regards,

RajDatta

Scott and for everyone else, here is my setup.
2.7 NA head
3.0 liter 968 block.
later 944 turbo S dme/klr setup and harness
APE/PH MAF
K27/8
52# injectors running at 3 bar off vacuum
Magnecore wires
New Ignition coil
New Distributor cap/Rotor
New speed sensor
944 turbo throttle body
Brand new Idle stabilizer valve
New O'ring on the idle adjustment screw
TPS clicks when on off throttle (its funny that when I setup TOS not to click, the idle rpm raises a little and I no longer have this drop problem but if I set it up for click, the rpms drop when warm and then stabilize)
Idle screw is only 1/4 turn out from fully closed
Chip is of unknown kind (came with the car) and the car pulls great and no hestation, runs very strong all the way to redline. Only problem is this idle drop when getting off throttle and then the shudder with idle stabilizing again and everything being normal.
Next I was going to try Danno's chip. I bought it setup for 52# injectors but never used it. This might be a good time to test it.
Raj

Ski

Setting the Idle on the 944 Turbo:

To do it correctly and throughly, it is a four step process.

Setting the hard stop. Car is not running. The purpose of the hard stop adjustment is to keep the throttle plate for binding or landing in the throttle body bore to hard. It's purpose is "not" to set the idle. Loosen the jam nut (8mm). Loosen the screw with a small straight blade screwdriver slowly and carefully until the screw turns loose. With a gentle touch, slowly turn the screw back in until you can feel it touch the stop. From there, turn it another 1/8 turn. Tighten the lock nut back down. If you have the intercooler pipe off, you would barely be able to detect that the throttle plate moved.

Setting the Throttle Position Sensor (TPS). Car is not running. A correctly adjusted throttle position sensor will make a clicking sound when you just roll the throttle off the stop. Place you fingers on the throttle cam and rotate the throttle open off idle. If it does not click, it's not adjusted properly. If it rotates several degrees before clicking, it's not adjusted properly. Loosen the two phillip screws on the TPS just enough to allow you to rotate it with a slight effort. Rotate the TPS to where when you rotate the throttle cam, it clicks when your just off the stop or about 1 degree of rotation. Then tighten the two TPS screws back down.

Jumping the Idle Stabilizer. Car is not running. You will need a short piece or wire (3-4") with both ends stripped bare. Place the ends of the wire in the terminals "B" and "C" pictured below. This will put the Idle Stabilizer in a central position of it's movement when the car is running.


Adjusting the idle RPM. With the previous three steps completed, you will be setting the idle RPM. With the car in neutral and the emergency brake on, start the car. Turn off the A/C if on. Let the car come up to normal operating temperature. The idle RPM is adjusted by turning the idle screw located on the top of the throttle body. Normally it will be approximately 1/2 turn open from fully seated down (clockwise). Idle should be 840+/-20 RPM.

RajDatta

Ski, just swapped TPS and things were looking good. I just did a little walkover to check everything was kosher while the engine warmed up and long and behold, leaky #2 injector. Turns out when I was installing the 522# injectors back on, the O'ring that slides into the fuel rail got pinched and then cracked.
I pulled the rail to see that 3 of the 4 injector O'rings were pinched so I am scrambling to find O'rings. Stock O'rings are too thick so they don't seem to fit too well. My weekend is in jeaopardy now. This hurts!!
Atleast the positive thing is that I caught it in time or else I would be having a 968 turbo S bar-be-que thing weekend. Anyone know where I can find them?
Raj

Ski

Hey Raj, just hit the parts stores, carry a good o-ring with you, surely you can find a match,,,before calling Lindsey.

RajDatta

Found some at Autozone but I had alredy ordered some from Lindsey, no biggie. Will have a few sets now, lol.
Raj