1989 190E 2.6 cold start problem

[milltek]

Hi,
This one's driving me nuts. The problem has gradually become so bad that the car now will not start without jumpering the Idle Air Speed Control Valve.

I have removed and used solvent to clean the inside of the Idle Air Speed Control Valve. The air passage is now clean and shiny. If I apply 12Volts and look inside I can see (and hear) it opening and closing.

When I re-installed it the car started fine about three times. Now, in order to get it started I have to remove the air cleaner box and apply 12 Volts to the Idle Air Speed Control Valve terminals. After about 20 - 25 seconds I can remove the jumper and it stumbles it's way to warmth. Once warm, the engine runs fine and idles fine. It will restart with no problems when warm as well. The problem is only when it's cold (overnight).

I have these questions;

i) Is it possible for a Idle Air Speed Control Valve to respond to 12Volts but not to the engine systems?

ii) There are three sensors on the top of the 89 2.6 engine block. Starting from the front there's a two pole, blue-based sensor. Next there's a single pole sensor and right at the back there's a black plastic-based four pole sensor. If one of these is suspect, which one is it?? Is there a way to test if the sensor is defective??

All help appreciated. I have spent a ton of $$ getting the a/c R7R'd and really don't want to throw more $$ into the car if I can avoid it.



Thanks,


Jim

[mctwin2kman]

The four pole one is the one that tells the CIS-E system the Engine Temp, to fire the Cold Start Valve and Actuate the Idle Air Control Valve as well as the EHA adjustments depending on engine temp. It is called the Water Temp Sensor.

[milltek]

Thanks,
Is there a way to test it? Or better yet, jumper it so that its telling the Idle Air Speed Valve that the engine is cold???



Jim

[mctwin2kman]

Test the poles diagonally accross from each other. Check the reistance and get back to us. Check it when cold and then when the engine is warm.

Values for cold should be higher than 600 ohms if I recall and around 270 or so when at 80.

[milltek]

Some update info;

I have replaced the distributor cap and rotor with new from the dealer. I have replaced the Water Temp Sensor and I have replaced the spark plugs. The car still idles rough and low until it warms a bit (30 - 120 seconds). Does anyone have any more ideas please???


Jim

[Porschetech9]

I decided to resurect this thread rather than start a new one since it already has some info in it. I have a 1989 190e 2.6 that stumbles pretty badly when started cold, smooths-out within about 5 minutes, (@ 60-70 deg. ambient temp), then the idles hunts up to ~1500 rpm at stop lights once the car is at operating temp.

I cleaned the idle control valve and tested it with a jump wire, it clicks and the valve inside just barely moves. Is it supposed to completely close when power is applied? I want to eliminate it as a problem before going further. Also welcome any experience with the symptoms I've posted, sound like typical ICV? Thanks in advance as always.

[zcc]

Check for vacuum leak. Search this forum for vacuum leak.

[lee polowczuk]

pull ovp and shake it.... if it rattles its bad... even if it doesnt rattle it could be bad..