'85-'86 32V idle control valve wear
08-31-2009, 05:06 PM
#16
Shameful Thread Killer
Rennlist Member
Rennlist Member
It's a circular shutter valve. Think of a focal plane shutter wrapped in a circle and you'll get the idea. It's rotated by the motor to maintain the correct amount of air bypass into the intake.
08-31-2009, 07:45 PM
#17
Inventor
Rennlist Member
Rennlist Member
Thread Starter
There is no seal, except for the case o-ring. There is >0.25mm clearance all the way around the shutter body. The motor is not isolated from the intake.
08-31-2009, 08:21 PM
#18
Nordschleife Master
Interesting, thanks.
Looks like almost any cleaning would be ok with the motor portion oriented up, allow it to dry/evaporate completely, then orient with motor down and apply a few drops of oil so it runs down the shaft.
Looks like almost any cleaning would be ok with the motor portion oriented up, allow it to dry/evaporate completely, then orient with motor down and apply a few drops of oil so it runs down the shaft.
08-31-2009, 09:01 PM
#19
So the S4+ is a 2 wire, but it uses the normal PWM right? This also uses PWM but has three wires?
08-31-2009, 09:48 PM
#20
Team Owner
I think that the bigger issue is the worn spots in the slip rings, once there are wear marks the motor can catch and then not move as the contacts will hold it in place. As Ken suggested a new part is the way to go here
09-01-2009, 02:48 PM
#21
Inventor
Rennlist Member
Rennlist Member
Thread Starter
The 2.2 LH uses two power transistors, and pulses ground to the open and close pins of the ICV. I logged it once, the pulses keep switching until pretty high in rpm, >3000 IIRC. Eventually, they level out with a 51% bias closed, IIRC.
I would like to try using an external circuit to disconnect the open circuit at WOT (or program the LH to open the ICV fully), to see if it the extra air would be noticeable.
09-01-2009, 05:57 PM
#23
I thought I read somewhere the S4-> ICV was a solenoid, but I'm probably wrong. I'm not sure if it is powered open, sprung close, either. The 2.3 LH may reverse the polarity.
The 2.2 LH uses two power transistors, and pulses ground to the open and close pins of the ICV. I logged it once, the pulses keep switching until pretty high in rpm, >3000 IIRC. Eventually, they level out with a 51% bias closed, IIRC.
I would like to try using an external circuit to disconnect the open circuit at WOT (or program the LH to open the ICV fully), to see if it the extra air would be noticeable.
The 2.2 LH uses two power transistors, and pulses ground to the open and close pins of the ICV. I logged it once, the pulses keep switching until pretty high in rpm, >3000 IIRC. Eventually, they level out with a 51% bias closed, IIRC.
I would like to try using an external circuit to disconnect the open circuit at WOT (or program the LH to open the ICV fully), to see if it the extra air would be noticeable.
12-29-2016, 10:34 AM
#24
Team Owner
since this thread addresses the early style ICV here is a link to how the 87 on S4 version works
https://rennlist.com/forums/928-foru...+control+valve
https://rennlist.com/forums/928-foru...+control+valve
12-29-2016, 11:48 PM
#25
Rennlist Member
I know that recently several of us were having issues with high idle when engines became warm...the answer was a new ICV but we had trouble finding them. I actually found the part at Pep Boys online of all places..it said Borg Warner on the outside of the box but it was actually the correct Bosch part.
Are we having any better luck now getting these?
Are we having any better luck now getting these?
10-31-2019, 01:37 AM
#27
This might seem unrelated but my 928 S4 1988 that has just been brought back to life after 12 years has a bit of a cold start issue, its not tooooo bad but if you dont hold the accelerator for a couple of seconds the revs bounce a bit then settle albeit a bit low.. Its also a little lumpy when the accelerator is held around 1000 rpm. Could this be the ICV ??? Ive got no way of checking, and no subsitute unless I go and buy anew one. On Ebay they are $ 82 USD for a LOWE one, are these OK ?? has anyone had good experience with these, there is a vast difference between these and Bosch in price....thoughts and comments appreciated.
Cheers
AL
Cheers
AL
12-28-2020, 12:32 AM
#28
Rennlist Member
Or: Why you can't fix a 100K mile S3 ICV IAC ISV by cleaning it, or spraying it with WD-40. 
If yours is original and your S3 won't idle, just buy a new one. Fuhgeddaboudit.
The LH2.2 32V ICV is a simple reversing motor which opens and closes a passage connecting the lower MAF/TB housing to the distribution pipe 'T' between the side plenums, bypassing the throttle plate. To maintain idle speed, the LH constantly pulses the valve open and closed.
Wear is indicated by difficult cold starting, high idle and/or stalling, and a drop in idle speed when the A/C is switched on.
This is a 150K+ mile ICV with deep wear (>0.5mm) grooves worn into the commutators. So deep the contacts no longer touch, just the edges of the spring arms are touching.
Also, I think that the o-ring seal could leak, and help cause the common S3 high idle?
Note that '87-up LH2.3 uses a simpler, solenoid type, ICV.
If yours is original and your S3 won't idle, just buy a new one. Fuhgeddaboudit.
The LH2.2 32V ICV is a simple reversing motor which opens and closes a passage connecting the lower MAF/TB housing to the distribution pipe 'T' between the side plenums, bypassing the throttle plate. To maintain idle speed, the LH constantly pulses the valve open and closed.
Wear is indicated by difficult cold starting, high idle and/or stalling, and a drop in idle speed when the A/C is switched on.
This is a 150K+ mile ICV with deep wear (>0.5mm) grooves worn into the commutators. So deep the contacts no longer touch, just the edges of the spring arms are touching.
Also, I think that the o-ring seal could leak, and help cause the common S3 high idle?
Note that '87-up LH2.3 uses a simpler, solenoid type, ICV.
I thought I read somewhere the S4-> ICV was a solenoid, but I'm probably wrong. I'm not sure if it is powered open, sprung close, either. The 2.3 LH may reverse the polarity.
The 2.2 LH uses two power transistors, and pulses ground to the open and close pins of the ICV. I logged it once, the pulses keep switching until pretty high in rpm, >3000 IIRC. Eventually, they level out with a 51% bias closed, IIRC.
I would like to try using an external circuit to disconnect the open circuit at WOT (or program the LH to open the ICV fully), to see if it the extra air would be noticeable.
The 2.2 LH uses two power transistors, and pulses ground to the open and close pins of the ICV. I logged it once, the pulses keep switching until pretty high in rpm, >3000 IIRC. Eventually, they level out with a 51% bias closed, IIRC.
I would like to try using an external circuit to disconnect the open circuit at WOT (or program the LH to open the ICV fully), to see if it the extra air would be noticeable.
Is there any way to test a S3 ICV/ISV when it is off the car? I suspect no, because it needs PWM to operate. I have idle problems, and I have a spare used ICV (928-606-161-00) of unknown origin in a box of parts. It would be a shame to buy a new one if this spare works fine.
12-28-2020, 10:54 AM
#29
Team Owner
to test it use a awl to move the vane inside the unit if it moves easily ,
IE isnt catching on anything when moved a slight amount then it should work in the car.
to test it electrically get a 3 pin amp connector ,
the center pin is ground,
the outer pins are close and open
IE isnt catching on anything when moved a slight amount then it should work in the car.
to test it electrically get a 3 pin amp connector ,
the center pin is ground,
the outer pins are close and open
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