anyone?

My dead spot is at 1000-2000 rpm when cold.
It was not that long ago when I replaced the fuel filter and 1 pump because it sounded funny.
Based on what just n time said about the ICV rpm should go up to 1900 I am going to try another one from the local pick a part. although this one works fine when I hit it with 12 volts it opens right up. The reason I replaced it was the other one did not close all the way there is a small gap you can see light thru.,but it works fine when voltage is applied.
I have also replaced the ICV hoses, the one that goes to the bottom of the fuel inj unit keeps splitting.

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

This is a picture of 91 300te m103 idle air control valve off the car with no voltage applied.
I have heard that this gap is the normal stopping point of the valve.
And 12v opens it right up.
Is this what yours looks like? Please post your results if you get another iac and find changes.

The hose at the cold injector could be a problem area for me, but propane and carb cleaner in the area change nothing. Will look further.


Another question: When I unplug the iac (at temp) and the idle drops, plugging the iac (this is 2 pin unit) back in does not change this idle at all.
So idle still low until I turn off and restart engine.
Is this your experience?
Just trying to do diagnostics to solve this symptom.
Gracias

Attached Thumbnails

 

My original unit looked like that with a gap in the valve.The one in there now from the junk yard has no gap! I am going to put the original back in since it tests good electricaly.

__________________
88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

Alright guys, I was mistaken. When I disconnected the IACV on my 190E 3.0, the idle dropped down lower. On my 420SEL it goes up to 1500rpm. I must have had them backwards. My apologies.

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82 300SD 145k
89 420SEL 210k
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There should be a small adjustment screw to set the gap. It is sealed but can be freed.

Rob

Pulled the ICV and tested it. ops good and has the gap in the valve ,also rechecked the ICV hoses they are good still.
The old ICV I had laying around is inop electricaly dead.,I dont know why I save this stuff???
I did the ohm tests on the cap ,rotor,wires,and coil all that stuff cks good,but I may just do a tune up to rule out any ign problems and maybe throw a fuel filter at it.
Also yesterday I threw in a coolant temp sensor it is the one that mounts at the rear of the head it is two prong green on my 103.Lets see what happens

__________________
88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

So original issue start die, low idle at first not the iac.
I replaced fuel filter, recent dist csap, rotor, nonresistor plugs, o2 sensor.
Tested the eha,
flow tested fuel volume(remove outlet connection on regulator, palstic tubing with hose clamp, minimum 1 liter/40 sec into plastic container),
tested temp sensor (4 prong on mine),
checked for vacuum leaks, replaced all small rubber connectors (not iac hoses)

Plan to check fuel pressure (need fittings), check valves at pumps,
check fuel accumulator this way:

Pinch off the 'return' from the accumulator and disconnect.
No fuel should should leak from the accumulator when you turn the key on, put a pan under just in case it's bad.


What I can't figure out on mine:

Have someone start the engine (cold only, warm starts fine).
Airflow plate drops and immediately starts back up, engine dies.
If I hold airflow plate in position (do not let it rise), does not die.
Tryning to figure out that one.
Did you observe the airflow plate in yours at cold start?

Update-
Adjusted duty cycle through tower on the air/fuel unit. This cw adjustment seems to have done what I was doing manually on the airflow plate.
Had to drill and remove the anti tamper ball.
Running lean, enriched- huge difference at cold start.
Measuring voltage at X11, pins 2 and 3, 90 degree turn (small increments) voltage from .5v to 6.8v.

Will the car start ok now? Is the problem gone with the car shutting off right after it fires up? My problem is worsening now! on acceleration I am getting detonation right where the dead spot is . Can my ign timing be off? maybe my timing chain is going bad? looked good when I did the valve stem seals...
I have also replaced the coil ,cap, rotor ,and cap cover the other day,No help

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

Car starts ok now.
But you say you have detonation at dead spot and I do not know what you mean. Detonation into intake manifold or backfire? While driving?

It is knocking as if I put in cheap regular gas instead of premium gas. very poor acceleration. runs great at highway speeds but very poor performance from a standing start. I have tried different types of premium,Shell,chevron,ect....... no help

__________________
88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

Have you used a voltmeter to check the duty cycle?
Real easy and will tell you if it is running rich or lean.

sorry took so long to reply been away for a while family emergency. I am planing to check the duty cycle again just for second guessing myself.
I thought it looked good when I checked it last.I am running out of parts to replace! I am following another post with a guy with a simillar problem now.

__________________
88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

Hi everyone
300E 1990

When I unplug the cable of ICV, I don't notice any change in rpm, however when I detach the ECU cable rpm changes. But with the ICV unpluged, detaching ECU cable doesn't have any effect. Moreover while opening the switch a soud like "click" can clearly be heard from the ICV. So I don't really understand whether it is working or not?
Any guidance is highly appreciated.