'82 Euro 500SEL, '85 Euro 500SEC AMG WB Cabriolet,'86 Euro 500SEC RUF
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9,498 Posts
Surging Idle Fixed.
Even after I had the local Indy set the CO mixture and check the timing the idle is still at 500 RPM warm or cold. I had an idle surge of a hundred RPM or so and finally cured it.
When I replaced all the rubber hoses in the car the two Elbows on the Idle Control Valve had the bypass tube between them, like the later models. One end of the tube was crimped and sealed shut. Thinking it should be open to work right, I opened it up. I had also changed out the ICV with a Gen II one.
Searching for the surge, I changed the ICV back to my working Gen I ICV. and I plugged the end of the bypass tube.
Voila! The surge was gone, cold or warm. Not sure and I don't really care which one of the two changes or both worked, but I'm guessing the the bypass tube being open(in a Gen I Euro) is a no, no, as the original rubber Elbows had no holes or provisions for the bypass tube. Later part numbers had the ports, but not drilled, and the latest part numbers have both the port and the holes cast in.
Gen II EZL in a Gen I Car.
Another thing I discovered, in a pinch, a Gen II EZL will work in a Gen I car. One simply plugs the 4 pin plug into the corresponding 4 pin on the EZL bottom right looking at the EZL, then plug the TDC Sensor wire into Crank Sensor plug on the top of the Gen II EZL. Good to go!
Even after I had the local Indy set the CO mixture and check the timing the idle is still at 500 RPM warm or cold. I had an idle surge of a hundred RPM or so and finally cured it.
When I replaced all the rubber hoses in the car the two Elbows on the Idle Control Valve had the bypass tube between them, like the later models. One end of the tube was crimped and sealed shut. Thinking it should be open to work right, I opened it up. I had also changed out the ICV with a Gen II one.
Searching for the surge, I changed the ICV back to my working Gen I ICV. and I plugged the end of the bypass tube.
Voila! The surge was gone, cold or warm. Not sure and I don't really care which one of the two changes or both worked, but I'm guessing the the bypass tube being open(in a Gen I Euro) is a no, no, as the original rubber Elbows had no holes or provisions for the bypass tube. Later part numbers had the ports, but not drilled, and the latest part numbers have both the port and the holes cast in.
Gen II EZL in a Gen I Car.
Another thing I discovered, in a pinch, a Gen II EZL will work in a Gen I car. One simply plugs the 4 pin plug into the corresponding 4 pin on the EZL bottom right looking at the EZL, then plug the TDC Sensor wire into Crank Sensor plug on the top of the Gen II EZL. Good to go!
