tazman

I get a high idle at times from 1000 - 1200 rpm. It does not pulsate it just picks a spot and hangs there every so often. The TPS has the click sound when it is closed and all. I have set the idle by bypassing the ICV and it has happened when the ICV was bypassed by jumping the test port. It seems to happen mostly when the car gets heat soaked sitting in traffic. I was thinking TPS but when it happens my A/F gauge goes towards the rich side and just sits there. My understanding is that when the TPS does not show the closed signal the A/F gauge should still dither and the idle usually pulsates along with that.

What do you think the problem could be what else should I check? This is a tough one because it doesn't happen all the time.

ringo951

I have the same problem, except mine picks 2000 rmp and idles there. Other times it idles around 900. The outside temperature doesn't matter. Just occasionally it decides to sit at 2000 or maybee 1500 rpm. It started doing it after I pulled and re-installed the AFM, throttle body, and intake. What's up...

Redeye

I get the same thing, but only after it's been running a while. It started about 1 or 2 months ago. Just as it started to get warm here in Phoenix.

Bri Bro

Check all the vacuum lines for cracks and loose connections. Also, the Idle controller connects to several rubber lines that tend to get hard and leak over time. When I pulled mine off, I could freely rotate all the connections and the rubber was hard and stiff. The line to the brake booster broke in two as I was removing it. This car spent most of it life in Texas so it saw the heat.

Also check that the throttle is at the stop. I had a throttle cable pull out of the mount on the fire wall, it would bind and cause a high idle on occasion.

Chipster

I had the same problem about a year ago. Initially, the idle would creep up to about 12-1400 rpm. It seemed to only happen when the engine heated-up but not all the time. Then it began happening with more regulatiry and eventually was happening every time I drove the car. I couldn't find the source of the problem. Then one day it started idling steady at 2000 rpm. At that point I began pulling parts off. I pulled the intake manifold and replaced the Idle Speed Regulator and Throttle position switch. I also cleaned the throttle spring thoroughly and replace several of the vacuum lines. Since some of the vac lines slid out of there connectors easily, I used small zip-ties to ensure a snug fit (I hear some use glue). I'm not sure which fix solved the problem, but the car now idles steady at 900 rpm. Also check the vacuum line that connects to the underside of the throttle body (hard to see) and that the TPS is plugged-in all the way. Both will cause a high idle problem. Good luck.

obie

I also had the same problem. I eventually tracked it down to the TPS switch, it turned out the resistor strip (reports throttle position)in it was bad and had the wrong resistance at idle, even though the TPS was 'clicking' at the proper spot. Replacing the TPS fix the problem.

rhesus

Idle stabilizer was the part that was mentioned to me when i had this problem. I haven't had a chance to replace it yet.
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=18;t=004177" target="_blank">My post.</a>

tazman

All my vac lines are new and I eliminated ICV. I think I will try readjusting the TPS when I get a chance. Maybe once everything gets heated up it is not getting the closed signal properly.

Thanks for all the tips!

alkemyst

things that can generally affect the idle are EGR, Idle Air Control/Control Valve, Throttle Position Sensor, and Air Temperature Sensors. Vacuum lines should be checked first though and various sprays can detect leaks.

I have a non-Porsche and got PCM codes thrown for the above....however it turned out to be my throttle body actually cracked in half...it was just a hairline and would idle sort of erradically until it warmed up then it would be ok...until one day it went to 4k rpms (neutral rev limit) and would not drop....I figured it was a bad gasket...however once I freed one of the two bolts holding it to the engine that entire half of the body fell to the ground....this was on a friday night after work <img border="0" title="" alt="[Frown]" src="frown.gif" />

turbite

I've been having this problem occasionally.
My TPS is set very very close to the click.
It only takes a little bit of pressure to make it click.
Its so close that it doesnt *always* click back into the no throttle position. So, in my case, I just thought it was the TPS getting hot and not returning to the no throttle position.

Let us know how it goes.

James86-951

I have the same problem and will be replacing the TPS. I could actually run along in traffic, release the gas pedal and the veh would still run like the pedal had not been released. (the idle would go to 2K as well.)

rhesus

Is there a write-up somewhere about adjusting the TPS?

sm

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by James86-951:
<strong>...release the gas pedal and the veh would still run like the pedal had not been released. (the idle would go to 2K as well.)</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I had the same problem and the reason was that the TPS wasn't returning to the idle position, even though it looked like it did. You have to make sure the TPS clicks when the throttle is closed/released.

So to solve the problem, I adjusted the throttle-stop screw on the driver-side of the throttle body to give the throttle-plate the travel it needed to make the TPS click.

Or you could just re-align the TPS itself, but it's a little more difficult with everything installed on the car.

Hope that helps...

Porscheman101

Alright, my problem is whenever I drive my car my idle picks up to 1200 rpm. So I screwed in the bolt at the top of the throttle body in farther. This solved the problem. Well after driving it again the rpm raised back up to 1200 at idle. So I took a look at the screw again and it had risen back up while driving.

So this is what is happening to my idle. I just dont know how to fix it. Tape maybe? Anyway thats my .02 cents on the situation. Maybe other 944 owners are having the same problem.

tazman

Porscheman I think there is suppose to be a rubber washer there that helps to stop it from backing out. Does your's have that?

rhesus all I know is you should make sure the throttle plate is not binding at all and have a little slack in the throttle cable. Then make sure the TPS has the click when you start to open it. If you don't hear the click you have to adjust the TPS on the side of the throttle body. This is just my take on how it should be done I guess we should both check <a href="http://www.clarks-garage.com" target="_blank">www.clarksgarage.com</a> I am sure he probably has the procedure on there.

I am unable to work on my car right now but I will post back when I get a chance to try this.