high idle- not the Idle air valve
01-02-2022, 06:50 PM
#1
Junior Member
Thread Starter
high idle- not the Idle air valve
Hi All,
I have a high idle problem on my 1992 190e 2.3. It is at about 1,100 RPM in park. This started in the past few months.
I removed the idle air valve and cleaned it. It was very clean inside and looks fairly new. I lubricated and tested it with a battery- operates perfectly.
No vacuum leaks, engine has had EXTENSIVE work (head-gasket, rebuilt fuel distributor, etc.)
It runs 100% perfectly other than the idle.
What else could it be?
P.S. Dolucase plz come back to benzworld
I have a high idle problem on my 1992 190e 2.3. It is at about 1,100 RPM in park. This started in the past few months.
I removed the idle air valve and cleaned it. It was very clean inside and looks fairly new. I lubricated and tested it with a battery- operates perfectly.
No vacuum leaks, engine has had EXTENSIVE work (head-gasket, rebuilt fuel distributor, etc.)
It runs 100% perfectly other than the idle.
What else could it be?
P.S. Dolucase plz come back to benzworld
01-02-2022, 09:51 PM
#2
Super Member
Hey Nate! Happy new year!
(1) I assume you already checked the obvious, that the OVP is in working order and your ECU is getting power.
(2) You can check above by looking for "any" voltage at the pins 3 to 2 on the X11 diagnostic port.
(3) Also check for the static duty cycle (ignition on, engine off) and make sure there are no codes being given by the ECU. It could be a benign code that only causes high rpm's
(4) You can also check for codes in the OBD1 port if you have a code reader, sometimes those codes do not trigger a CEL.
(5) Unplug the IACV after the engine warms up and with the engine running, does the idle change at all? If it does then try 6.
(6) check the voltage on your IACV while it is plugged in and engine running. You will need a voltmeter and two skinny wires wire rapped to the male side of the connector for this. Try not to short these wires as I do not know how well the ECU is protected against a short circuit, it would be since this is an automotive application but why test it?
If all 6 above check out we can dive in deeper. You can try 5 first since it is so easy.
(1) I assume you already checked the obvious, that the OVP is in working order and your ECU is getting power.
(2) You can check above by looking for "any" voltage at the pins 3 to 2 on the X11 diagnostic port.
(3) Also check for the static duty cycle (ignition on, engine off) and make sure there are no codes being given by the ECU. It could be a benign code that only causes high rpm's
(4) You can also check for codes in the OBD1 port if you have a code reader, sometimes those codes do not trigger a CEL.
(5) Unplug the IACV after the engine warms up and with the engine running, does the idle change at all? If it does then try 6.
(6) check the voltage on your IACV while it is plugged in and engine running. You will need a voltmeter and two skinny wires wire rapped to the male side of the connector for this. Try not to short these wires as I do not know how well the ECU is protected against a short circuit, it would be since this is an automotive application but why test it?
If all 6 above check out we can dive in deeper. You can try 5 first since it is so easy.
01-03-2022, 03:54 PM
#3
Super Member
One thing I forgot to mention above among the obvious is the throttle linkage issues. Please make sure things are in order there like throttle cable, and the microswitch is switching to the idle position properly.
01-08-2022, 09:58 PM
#4
Junior Member
Thread Starter
thanks Dolucasi and happy new year ,
So today I was out driving today and the issue disappeared? Definitely seems to be electrical.
Duty cycle was verified a few days ago when it was idling high, it is reading properly. No CEL codes.
OVP was replaced a couple years ago but it was a cheap aftermarket, maybe it is defective.
Are there any temp sensors that would cause this?
So today I was out driving today and the issue disappeared? Definitely seems to be electrical.
Duty cycle was verified a few days ago when it was idling high, it is reading properly. No CEL codes.
OVP was replaced a couple years ago but it was a cheap aftermarket, maybe it is defective.
Are there any temp sensors that would cause this?
01-08-2022, 10:41 PM
#5
Super Member
Hi Nate. Sounds electrical. A faulty circuit in the coolant temp sensor could possibly cause this but not in your case.
You have already verified that when you had the high idle the duty cycle was normal meaning your temp sensor was telling the ECU the correct temp and the ECU was properly adjusting duty cycle but yet your idle was high. This also vindicates the OVP, at least at that instant that was not the problem.
Next time this happens make sure you try unplugging the IACV while it is running and let us know what happens.
It is more likely that there is a fault with the micro-switch. Have you checked that for proper operation? Remember that switch tells the ECU to put the engine in "idle speed control"
It maybe acting up or there is mechanical issue with the alignment of the throttle actuators.
- Cheers!
You have already verified that when you had the high idle the duty cycle was normal meaning your temp sensor was telling the ECU the correct temp and the ECU was properly adjusting duty cycle but yet your idle was high. This also vindicates the OVP, at least at that instant that was not the problem.
Next time this happens make sure you try unplugging the IACV while it is running and let us know what happens.
It is more likely that there is a fault with the micro-switch. Have you checked that for proper operation? Remember that switch tells the ECU to put the engine in "idle speed control"
It maybe acting up or there is mechanical issue with the alignment of the throttle actuators.
- Cheers!
