The car is Canadian spec., 1986 190E 2.3-16V. I've had this same problem ever since I bought the car a year ago. The car idles between 1200 and 1500rpm. I have been to the dealer with no success in addition to "specialists", etc. The car has been totally refurbished from the ground up but this problem remains. The last fix was to place a rubber bushing to act as "restrictor" after the idle stability valve. This causes warm-up to take 15 minutes in the morning but keeps the idle at 900rpm. Everyone says the problem is the ECU. So I exchanged ECU with a friend with a German spec. 16V and the same problem remained (but with slightly more power available). It must be noted that the car now runs on leaded fuel with cat removed. Today we installed an O2 sensor but there was no difference in idle. The car brochure says that for converting from unleaded to leaded or vice versa, two plugs must be changed in the engine compartment to inform the ECU in which mode to run. These plugs are unavailable anywhere here. One of my plugs has a resistor and the other is just short circuited.

A final note is that idle goes down when the A/C is turned on. When idling at 1500rpm, it drops to 1200rpm. When idling at 900rpm with the restrictor, it idles at 600rpm and stalls when coming to a halt.

After exhausting all technical capabilities in this country, I have only the net to trun to. Please help me rid this car of this disease. Thanks.


Basel Dahham
Amman, Jordan.

Have you checked the idle speed actuator? It's sole responsiblity is to correct the idle speed via the ECM. Be sure to check for any large vacuum leaks!!

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM




[This message has been edited by Benzmac (edited 05-12-99).]

Where is this speed actuator loacted? Is it the cylindrical thing about 5 inches long underneath the intake manifold. If it is this, then should it be nonadjustable (my case) or should it have a black screw to adjust the idle speed? Someone recommended using the adjustable type to lower the idle speed. Others say the 2.3-16 came with nonadjustable type (ECU controls idle). Which is correct?

Has ayone had experience dealing with the plugs that convert leaded into unleaded?

I don't recall which one the 16v came with, have a dealer look it up on the parts fische.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I have posted this at least 4 previous times, Mercedes issued an internal bulletin regarding this problem in 1988. Due to computer design(fixed oper. mode) any problem with the air-flow sensor will cause the idle speed to be erratic!! Have it tested for an intermittant open or shorted resistance reading!

I realize by now, I must be a PITA but the local (Jordan) dealer doesn't even admit the car into the workshop since it is not local specs. So any information on this internal bulletin would be most helpful since I must get this problem fixed on my own. I can send you my email if there is any useful information you might have compiled over time. Thanks once again.

Since this bulletin was for "internal" use only I can't share it, but all 16V engines from 1986-1987 No. America spec. are affected. Possibly other versions have the same problem since they use the same part #.
the only "fix" is to replace the complete air flow sensor housing.