Very High Idle
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From: Houma, LA.
khalloudy, this probably won't be any help but I'll just put it out there since it happened to me. I'm not proud of it but I had a high idle caused by the floor mat pushing excessively on the accelerator. I know STUPID! Make sure your throttle able is getting slack at the engine. The idle stablizer takes over after the cable goes slacked.
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From: Riyadh, KSA
So i went and bought a Mighty Vac, plugged it to the Intake Manifold, the car running, i was showing 16/17" Hg (is this low? i have seen other posts with about 22"). Anyways, the car was idling at 1000-1100rpm. When i rev it up, the Manifold pressure drops, then rises to about 20/22".
Checked all the fuel pressure diaphragms, and they are all running well, no issues there. Checked the vacuum at one of the diaphragms in the rear, about 18" steady. Sprayed starter fluid around the engine, no noticeable change in rpm. I am potentially running out of options on the vacuum leak potential.
Checked the slack at the throttle body connection, and it looks fine (even disconnected it, and no change). Checked if the throttle body is making the closing click, and it did, so that means it is closing well.
Idle stabilizer tested fine with the Hammer actuator test.
Temp II sensor seems to be working fine with the signal present at both EZK and LH
Now thinking again about the O2 sensor sending a rich signal... makes me think and wonder about the MAF. I have replaced it a few months ago with a rebuilt JDS one. Could the MAF have an issue and is running funky making the car run at a higher RPM?
What else is there?
Going crazy!!!!
Checked all the fuel pressure diaphragms, and they are all running well, no issues there. Checked the vacuum at one of the diaphragms in the rear, about 18" steady. Sprayed starter fluid around the engine, no noticeable change in rpm. I am potentially running out of options on the vacuum leak potential.
Checked the slack at the throttle body connection, and it looks fine (even disconnected it, and no change). Checked if the throttle body is making the closing click, and it did, so that means it is closing well.
Idle stabilizer tested fine with the Hammer actuator test.
Temp II sensor seems to be working fine with the signal present at both EZK and LH
Now thinking again about the O2 sensor sending a rich signal... makes me think and wonder about the MAF. I have replaced it a few months ago with a rebuilt JDS one. Could the MAF have an issue and is running funky making the car run at a higher RPM?
What else is there?
Going crazy!!!!
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From: Riyadh, KSA
I think i pretty much gave up based on my knowledge and skills... i will be taking it to my mechanic for a 4 hour diagnostics this week... i hope it is not something below the intake as we have just reassembled it... show be good underneath... ahhh those cars are funky 
but i love them
but i love them
Burning Brakes
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From: Portland, Oregon
Originally Posted by khalloudy
I think i pretty much gave up based on my knowledge and skills... i will be taking it to my mechanic for a 4 hour diagnostics this week... i hope it is not something below the intake as we have just reassembled it... show be good underneath... ahhh those cars are funky but i love them
but i love themDefinitely not the valve guides, nothing really points to that being your problem.
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From: AZ
Originally Posted by pmotts
I am guessing it's an vacuum/intake leak. Didn't this all start right after your intake refurbish?
Definitely not the valve guides, nothing really points to that being your problem.
Definitely not the valve guides, nothing really points to that being your problem.
The fact that in the past he had a lot of oil in the intake manifold, it smoked after restarting and then cleared up, AND has over 185,000 miles on the odo to me is an indication of worn out valve guildes (I'm pretty sure that the rings have been replaced). He has installed the GTS breathing upgrade and a 944T air - oil separator. My bone stock '87 S4 has 95K miles and doesn't use a drop of oil and has never smoked - so the engine design isn't the problem.
If it was my 928, I would do the valve job JUST to have a fresh engine, pretty much everything else in this car has been freshened - why ignore the valve train? 185,000 miles miles provides a fair amount of wear on valve components - all the tweaking in the world to reduce symptoms won't take away wear on components.
Burning Brakes
Joined: May 2006
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From: Portland, Oregon
I missed that.
I still don't think it's the valve guides but we are all just guessing. And no. I am not a mechanoc.
There are a lot of 928's out there that use oil that don't have high idle problems. No doubt replacing the valve guides would have been prudent but for Khaled's sake I hope you are wrong.
I still don't think it's the valve guides but we are all just guessing. And no. I am not a mechanoc.
There are a lot of 928's out there that use oil that don't have high idle problems. No doubt replacing the valve guides would have been prudent but for Khaled's sake I hope you are wrong.
Originally Posted by Rich9928p
The problem did not start right after the intake refurbish. He stated that it happended after replacing the EZK. However, we confirmed that the high idle is not due to the EZK or LH. It was most likely just a problem that occured at the same time.
The fact that in the past he had a lot of oil in the intake manifold, it smoked after restarting and then cleared up, AND has over 185,000 miles on the odo to me is an indication of worn out valve guildes (I'm pretty sure that the rings have been replaced). He has installed the GTS breathing upgrade and a 944T air - oil separator. My bone stock '87 S4 has 95K miles and doesn't use a drop of oil and has never smoked - so the engine design isn't the problem.
If it was my 928, I would do the valve job JUST to have a fresh engine, pretty much everything else in this car has been freshened - why ignore the valve train? 185,000 miles miles provides a fair amount of wear on valve components - all the tweaking in the world to reduce symptoms won't take away wear on components.
The fact that in the past he had a lot of oil in the intake manifold, it smoked after restarting and then cleared up, AND has over 185,000 miles on the odo to me is an indication of worn out valve guildes (I'm pretty sure that the rings have been replaced). He has installed the GTS breathing upgrade and a 944T air - oil separator. My bone stock '87 S4 has 95K miles and doesn't use a drop of oil and has never smoked - so the engine design isn't the problem.
If it was my 928, I would do the valve job JUST to have a fresh engine, pretty much everything else in this car has been freshened - why ignore the valve train? 185,000 miles miles provides a fair amount of wear on valve components - all the tweaking in the world to reduce symptoms won't take away wear on components.
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Thread Starter
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From: Riyadh, KSA
I seriously doubt it is the valve guides to be honest, actually doubt it. Since installing the GTS breather, just like John Fagerlund, i went from using oil to not using any and no more smoke at start. Regardless, I drive the car hard and at high RPM sucking more oil which is normal. Now that has been fixed.
As far as the high Idle, it is interesting... probably a vacuum leak somewhere (i mean i know for a fact that the idle stabilizer is not doing squat to adjust it - weird). Also suspect is the MAF. I will be pulling out both my EZK and LH to test off the car, maybe on Rich's car ;-) i have tested new parts from him, but want to take my parts out too maybe? i have no clue, this is weird.
As far as the high Idle, it is interesting... probably a vacuum leak somewhere (i mean i know for a fact that the idle stabilizer is not doing squat to adjust it - weird). Also suspect is the MAF. I will be pulling out both my EZK and LH to test off the car, maybe on Rich's car ;-) i have tested new parts from him, but want to take my parts out too maybe? i have no clue, this is weird.
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From: Riyadh, KSA
Bill,
That sounds like something i should do. Where is the idle stabilizer plug you mentioned above?
P.S.
I was working on my car today and here are a couple of points:
1- checked the Temp Sensor II after the car has been sitting for a couple of days
EZK - 1139 Ohms ~ 40 deg C
LH - 1138 Ohms ~ 40 deg C
sounds like the NTCII is relaying the data correctly both warm and sitting
2- Checked the vacuum at idle (car idling about 900rpm), it was showing stable 17" Hg... this is a cause of concern considering i have see Shocki's check and his car was running about 20.5" Hg? this could mean i have a vacuum loss somewhere
3- Disconnected LH and EZK, then reconnected after a while, the car started up and for about a couple of minutes it was attempting to adjust itself, then it was idling about 675rpm!!!! shocking. Once the car warmed up a little another 3 minutes, the rpm rose to about 900rpm!!!
This is perplexing.
Sincerely,
That sounds like something i should do. Where is the idle stabilizer plug you mentioned above?
P.S.
I was working on my car today and here are a couple of points:
1- checked the Temp Sensor II after the car has been sitting for a couple of days
EZK - 1139 Ohms ~ 40 deg C
LH - 1138 Ohms ~ 40 deg C
sounds like the NTCII is relaying the data correctly both warm and sitting
2- Checked the vacuum at idle (car idling about 900rpm), it was showing stable 17" Hg... this is a cause of concern considering i have see Shocki's check and his car was running about 20.5" Hg? this could mean i have a vacuum loss somewhere
3- Disconnected LH and EZK, then reconnected after a while, the car started up and for about a couple of minutes it was attempting to adjust itself, then it was idling about 675rpm!!!! shocking. Once the car warmed up a little another 3 minutes, the rpm rose to about 900rpm!!!
This is perplexing.
Sincerely,
Drifting
Joined: Nov 2003
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From: London, UK
Originally Posted by khalloudy
Bill,
That sounds like something i should do. Where is the idle stabilizer plug you mentioned above?
That sounds like something i should do. Where is the idle stabilizer plug you mentioned above?
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From: AZ
Originally Posted by UKKid35
Luckily it's in the most imposible place imaginable. Between the throttle body and the V, with the connector facing in to the V. Whose bright idea was that? Why on earth it couldn't be the other way round - I have no clue.
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From: Riyadh, KSA
Since this is almost impossible to access, maybe i can just pinch the vacuum line to the ISV cutting off the air to it and see what happens? this should act like i turned off the ISV? what do you guys think?
Under the Lift
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From: Buckeye, AZ
Yeah, sorry about that. The ISV was relocated into plain view with my SC install, so I guess I was speaking theoretically in your case. The plug faces the rear and is obstruted such that I don't think it can be reached even with some kind of skinny tool and mirrors even with the MAF removed. I don't understand the stock plumbing to the ISV - my altered plumbing is simpler. So, I'm not sure pinching of the manifold vacuum will eliminate it, although I believe it will. Look at this: