cjb3

Hello,

I recently rebuilt my engine and have installed it.

At start it runs up to about 2000 RPM and then back to about 1000. It is near clock work---1000rpm---runs up to 2000rpm. The thing is that I have tried everything I know to do and have had no result whatsoever.

I have tried the following:

--replaced the 02---as well as just unplugged it while running---no result
--replaced the TPS---no result
--confirmed the ISV works as well as unplugged it while running--no result
--changed the DME temp sensor(the blue one)---no result
--checked the intercooler hoses and other connections---no holes
--changed the Huntley Mass Flow Meter-(swapped with another)--no result
--checked the fuel pressure-around 40lbs(idle)--52lb injectors--I think that is ok
--plenty of Vacuum in Intake(10-17lbs)
--tried to adjust the idle screw---does nothing whatsoever
--over 2000 RPM it seems to run OK though I have not driven it
--the Split Sec AF Ratio shows running lean then rich

The crank and flywheel were lightened during the rebuild and the flywheel sensors were both replaced with no result once again.

Could the DME be shot, maybe a relay.

Any thoughts gratefully appreciated,

Sincerely,

Cy

ibkevin

Describe what happens over 2k.

cjb3

Seems just fine---though that it was just rebuilt I have not run the RPMs too high

Ski

Have you tried to set your idle with the IAS shorted out on the diagnostic port, then set your TB screw?

Did you rebuild the TB during all of this, here is the complete procedure from Lindseys site:

Setting the Idle on the 944 Turbo:
To do it correctly and thoroughly, is a four step process.

1) Setting the hard stop. Car is not running. The purpose of the hard stop adjustment is to keep the throttle plate from binding or landing in the throttle body bore too 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.

2) 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 your 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 you're just off the stop or about 1 degree of rotation. Then tighten the two TPS screws back down.

3) Jumping the Idle Stabilizer. Car is not running. You will need a short piece of 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.



4) 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.

cjb3

The TB was not rebuilt---and the TPS was not adjusted---I swapped the entire intake--TB--TPS
from another car---and saw no change.

As for the ISV---I can give that a try--I did have to rewire the ISV--maybe I crossed the wires, but there was no improvement at all when the ISV was disconnected while running the car.

Will advise--many thanks

Tom M'Guinn

If you physically confirmed the throttle cable is not pulling on the throttle at idle -- this can happen if either the throttle cable or the cruise control cable are too tight. Just a thought. What are you using to control the Huntley MAF -- an ARC2?

Did you clean out the ISV when it was out, with carb cleaner. They can stick open, even if electronically disconnected or bypassed, causing idle problems or fast idles.

cjb3

Yes the cable to the throttle is OK---the cruise is not yet hooked up---and I am using the ARC2.

I cleaned the ISV with carb cleaner and put power to both motors--it seems to be working just fine.
If it was stuck open would that cause it to rev?

It seems really wierd that even when unplugging the O2 or the ISV there is no change at all in the revs.

cjb3

Tom---I even switched out the MAF with a friend running the same setup--still no good.

Tom M'Guinn

Well, if it is revving to 2k, it must be getting air somewhere. Any chance air is getting in at the turbo where the MAF couple squeezes by the alternator shroud?

cjb3

That was the first thing I checked--and I have looked at all of the connectors for the intercooler pipes as well as pulled the intake and checked the ISV - Ventrui hoses.

I agree---I just can't find a leak.

Tom M'Guinn

Brake booster?

special tool

When the ignition is off, you hear a "click" from the TPS upon moving the throttle plate immediately off closed, correct?

cjb3

I have not looked at the brake booster but that is easy enough to check.

Regarding the TPS---both that I have used clicked no problem.

cjb3

Tom---I am going back to the air leak theory---that is the only thing I can think of that would
overload everything--I am also going to block of the ISV to the intake and see if there is any effect.

cjb3

OK---may some headway this morning---I stopped the air flow from the ISV to the intake---though the car would not idle it did smooth out completely---I guess the ISV is stuck open??? Though it did work fine when I put power to it--and it did not stick when I had it out of the car---I did use carb cleaner on it anyway.

Will advise later-----thanks for your suggestion guys--Cy