MadMax

My '91 S2 sometimes idles smooth and steady. But most of the time, the idle 'hunts' from ~820-900 rpm and when it dips down to 820 it shudders a little as it seems to recover to normal idle. It stays there for a couple of heart beats and then repeats this scenario. It is even more pronounced with the a/c running. Any advice or ideas?

Regards,

TomH

Max, I've been plagued by the same problem, and have resolved to "get use to it." I'm convinced its my dirty idle control valve, which is buried underneath the intake manifold, and beyone my abilities to either remove and clean, or replace altogether.

When your car is acting up, try tapping the canister with a screw driver, to see if it helps. If it does, then you likely have the same problem.

With my car, it acted up more during colder weather, so I'm not really in a hurry, yet, to deal with it.

We could of course get our hands dirty, and fix them both. I'll even be the test subject

MadMax

TomH,
I will give that tapping thing a try to see if it helps. The idle stabilizer on the S2 appears to be a little easier to get to. I may try cleaning it this Friday. I am not going to work so I am going to the Auto Hobby shop to replace my left wheel bearing and look into this idle speed stabilizer issue. It's the only day I can do it because I have a huge assignment due for Law School. If you can get away from work maybe we could have a look at your too.

Max

TomH

Max, sent you an email. Would you have time to help me on Friday with the motor mounts?

MadMax

TomH,
Let's plan for it. I have emailed you my work number so you can give me a ring and we can work out the details. The Auto Hobby shop doesn't open until noon. I can reserve the 'lift bay' and we will be ready to go.
Give me a call.

Max

s2cabpilot

Max, I live in DC and I am having the same problem. When the car warms up and I shut it down, when I restart the car it begins the hunting issue with the RPMs you describe. My shifter shakes hard and it is very annoying. If you get a fix for this let me know

Michael Stephenson

I had this exact problem happen to me as I was going to meet a fellow 944 owner (Cliff Hipsher) for his 50th Birthday this past Friday.

When I got to the meeting place, we opened the hood and he jiggled my the connection by the TPS. The car went back to its normal idle.

Michael Stephenson

Just saw this on the 924/944/968 E-mail digest from Saturday posted by Dal Heger <dalibor-heger@utulsa.edu> to a similar problem (hope you do not mind the reprint, Dal):

"could be a faulty throttle position sensor. Easy one to check. With the engine OFF, move
the throttle and you should hear a little click as you just move throttle. The Sensor is a little black box on the side of the throttle body. If you don't hear the click then your throttle position sensor is shot and should be replaced. It isn't telling the DME that the throttle is closed and it should activate the idle program. The DME just sees the revs drop too much and compensates the best it can, thinking that the throttle is still open."

MadMax

Thanks for all the input guys. I will look into this problem again and post the results. I am surprised at how few responses this post got considering how common the problem is. Thanks again for all of your input.

Regards,
Max

IPC

TPS very likley the problem. If you don't here the click don't replace just yet. Remove the intake boot off of the throttle body and clean the throttle body and plate. It may have a build-up of carbon on it and this does not allow the plate to close completely. So the TPS will not click if this is the case. Clean it then listen for the click. If you still have a problem, while the car is surging or hunting unplug the O2 sensor, it may be getting slow or sluggish this can also cause the same problem. Happy hunting. (No pun intented) [img]null[/img]

MadMax

Well,
Yesterday afternoon I checked the TPS. That ain't the problem. I can hear a very distinct 'click' when the throttle opens and closes. I will remove the Idle control valve this weekend. It looks like a PITA on the S2. Very difficult to get off w/o removing the intake manifold. I don't want to remove the manifold! I'm going to have to get some 1.5-2" hose clamps so I can replace the factory ones after I remove them. This doesn't look like it is going to be a straight forward (easy) removal. We will see. I hope cleaning this piece fixes the problem. I may also try the O2 sensor connection before I remove the Idle control valve. Any advice from the S2 crowd on removing this item would be greatly apprciated.

Regards,
Max

JGriff

[quote]Originally posted by MadMax:
<strong>Well,
Yesterday afternoon I checked the TPS. That ain't the problem. I can hear a very distinct 'click' when the throttle opens and closes. I will remove the Idle control valve this weekend. It looks like a PITA on the S2. Very difficult to get off w/o removing the intake manifold. I don't want to remove the manifold! I'm going to have to get some 1.5-2" hose clamps so I can replace the factory ones after I remove them. This doesn't look like it is going to be a straight forward (easy) removal. We will see. I hope cleaning this piece fixes the problem. I may also try the O2 sensor connection before I remove the Idle control valve. Any advice from the S2 crowd on removing this item would be greatly apprciated.

Regards,
Max</strong><hr></blockquote>

Did you ever figure this out? I ask because I am having the exact same problem. I hate it. It sure takes away from the pleasure of driving the car.

I'll check the TPS for a click, as described in this thread, and I'll also look at cleaning the throttle body first. I was going to do that this past weekend, but didn't find the time.

BTW, where exactly is the idle stabilizer valve located? Does anyone have a pic of it?

Also, where is the canister that is mentioned in this thread?

Thanks.

Jim

PorscheG96

My 944 has it too. Where is my idle control valve located?

JGriff

My problem has been cured!! Yeehaw!! <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

I brought it in to have it checked out (by Bill Pfister at Eurotech in Framingham MA... great guy/place BTW), and I ended up replacing both the Throttle Position Sensor and the Idle Adjustment Valve.

First, he checked for vacuum leaks. All was fine. He then checked the TPS, and said that it needed to be replaced. After replacing the TPS, he said that the idle still wasn't quite perfect (i.e. still some erratic movement), so he went ahead and replaced the ISV.

I took a look at the old ISV, and it definitely needed replacement... it didn't move freely, and it wasn't opening/closing all the way.

The car now idles perfectly smooth.

Hope that helps.

Jim

Ken D

Jim,

Sorry to take this a bit off topic..but have you used Eurotech in the past? I'm looking for a new shop and don't know anything about them.
I tried Rennsport (also in Framingham) but they won't do 944 work.

TIA,