rpm on idle unsteady; can't open hatch

[vamp67]

Lately the idle on my late 1985 has been bobbing up and down. Is this a setting problem or maybe the timing belt is worn? The car has not been tuned up in a while.

Also the hatch is stuck. The rubber on the passenger side is pushed in. I kinda wonder if someone tried to break in.... grrr....

[944 Ecology]

The cause of your unsteady idle is most likely the Digital Idle Stabilizer, which is a rotary valve that allows additional air to bypass the throttle to bump up the idle when it is low. The valve can stick, causing the unsteady idle. Remove the DIS and clean it out with some brake cleaner. If that doesn't work, you may have to replace it.

I don't know why your hatch is stuck... some pictures or a video might help to diagnose it.

[OK-944]

Before you remove the idle stabilizer, you can check its basic operation by unplugging its connection and, while its still in place, jump wires from a 9v battery to center and either of the other two ISV contacts.

If all is well, you should hear (and feel) a good healthy "click." If no response, remove it and clean as suggested, then test again prior to re installation to see if its come around. You may need to bend some metal tabs to take off the ISV's cover, which allows the removal of the core so you can check the deflection of the three stators and for age/use related grooving on the rotor shaft. Stators and be cleaned and bent inwards to re-establish contact with the rotor if necessary, but if the rotor is also excessively grooved this will only be a temporary fix (ask me how I know!). In any case...do not forget to replace the rubber sealing ring (hold vacuum) under the ICV cover!

Somewhat of a PIA to do this...but new ICV's are expensive! (have heard that a less expensive Audi unit may be compatible?)

[vamp67]

thanks very much!!

Did not manage to attach a picture, will try adding to my profile. The gap is about an inch deep, as shown by my finger, and is along most of the side.

Anne

[vamp67]

pic will not upload in garage either, maybe too high resolution. dang

[mytrplseven]

When I was searching for a "new" idle stabilization valve I found that O'reillys Auto Parts sells a new replacement for good prices. On the hatch, see if it will open with a key. If that doesn't work then crawl into the back, pull down the carpet and move the mechanism with your hand to release the latches. Once it's open, see if the mechanisms work electrically. then see if they move with a key. If they do then you have latch adjustment issues. Remove the latches, clean them and reinstall them with finger tight on the two nuts. Close the hatch slowly to see if the pins are penetrating properly into the holes. If they don't then the hinges for the hatch or the pin receivers need to be readjusted. Also be sure to lubricate the claws on the receivers with a light grease.

[vamp67]

thanks!!
The key does not help, so it is the latches. Being 5 foot tall is an asset for a few things.

[walfreyydo]

Surging idle is most commonly associated with a vacuum leak.

Easy way to check is to set the engine at TDC and pressurize the intake with around 10psi and listen for leaks. Its important that the engine is at TDC so the air doesn't just bleed into the combustion chamber and not pressurize the intake system.

I would check this first, as removing the ICV requires removal of the intake manifold, fuel rail which is a somewhat involved process. You can also test the ICV operation as OK-944 mentioned.

[vamp67]

thanks very much - I will need help on this one.

The idle settles down after a bit - this is almost entirely when I start the car up. Maybe that is a clue.

[Lewis774]

Sometimes my hatch sticks and slightly bumping the left or right side will allow the plungers to move out of the holes and it will open.

[OK-944]

Vamp...if you're idle is wonky at startup - this could mean that your dme temperature sensor (look for the blue connector plug on the cylinder head, just underneath the back of the J-boot) is not operating correctly. This sensor ordinarily helps to smooth out the engine until it warm up.

There is a way to test this sensor, which I think you'll find by going to Clarks Garage.

I replaced mine recently with a unit from Bosch (less $$ than the Porsche version), and it only took a few minutes. I would ordinarily do my best to thoroughly diagnose an issue before going crazy buying parts...but this sensor is cheap enough that I just went ahead and replaced it.

A general question: have you checked your grounds? If not you should, and if they exhibit any corrosion, then by all means clean them up!

[vamp67]

thank you. I will check the grounds. I cleaned the battery connections recently, and reseated the fuses.

It has some electrical quirks. Generally either the RMP is registering or the MPH, but not both. The oil temp sensor works, but not the pressure sensor. Out of the blue, the car now beeps if I dont have my seat belt on.

Now I have another problem, squeeking, particularly when turning. The power steering fluid leaks slowly, but now the leak is faster. I'm not sure if this is the power steering belt or the serpentine belt. I'm also not sure if I should drive it to a shop that I use (not porsche). Will post separately on this.

I want to fix the car to the point that I can sell it. Its a love/hate relationship.
Anne