Hi , I checked and replaced damaged vacuum lines and replaced a missing imtake bolt. Held accelerator open to about 3000 /rpm. Sprayed 1/2 can of gumout
carb cleaner into intake. When I was finished, I started car and it idled
perfectly at 700 rpm for about 1 minute hiccuped and stalled. Started it again and
it idled perfectly for about 30 Sec and hiccupped and stalled, Started again,
and it would not idle at all-just like when I began, Idle control module has
been replaced. What gets replaced next, and where do I find it? fortunately, I have a parts car. Thanks in advance for your thoughts, Len

I would try the idle air valve. Sits on the intake manifold in front of the injection and has large black hose running to it. You can try cleaning its internals with the remaining carb cleaner - letting it soak for a while. Be careful of the hoses - they get hard and crack very easily.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

I will try that. Thank you for your help. Len

You were correct -I replaced the air Idle valve, and now it idles, I can only get about 400 RM. I alllowed it to fully warm up and still idles around 400, or a little less. What now? Thanks, Len

You need some more air!

Pull the wiring connector off the idle air valve so that you can get your multimeter leads on the two pins. Measure the voltage at idle. If it is 4-6V, then you may have a blockage in the air tubes or the tubes may be leaking or the valve might still be flakey.

If the voltage is not in this range, the idle relay may have something wrong with it.

You can increase the idle by pulling the connector off the coolant sensor at the very rear of the right cylinder head, and bridging the two contacts in the connector with an alligator clip or piece of wire. That should bring the idle up to 750 or so.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks Chuck, How about that allen screw in the center, through the air cleaner, to increase idle? Len

That is the mixture screw, not the idle. You might try maybe 1/8 turn to the right (richer) to see if it makes a difference, but if it is idling smoothly at 400 RPM, I would not mess much with the mixture.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

You can increase the idle by pulling the connector off the coolant sensor at the very rear of the right cylinder head, and bridging the two contacts in the connector with an alligator clip or piece of wire. That should bring the idle up to 750 or so.
This caused no change in idle speed, nor did the screw in the center of Air cleaner- just made it stall. Idle seems to gallop up and down when first started, Thanks, Len

If the coolant sensor test fails, the book says to connect 12V to the idle valve for 5 seconds. If the engine slows way down or dies, replace the idle relay. If it does not, replace the idle valve.

Did you ever check the voltage to the valve?

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks, I'll try that tomorrow. I took the car for a ride, and you are right. It is running extremely rich. I do need more air, as you said. Len