Air Flow Meter Adjustment 85 500 sel
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Joined: Jun 2012
Posts: 40
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1985 Mercedes 500 SEL
Air Flow Meter Adjustment 85 500 sel
A MB mechanic (60-mile away) had removed the original air Flow Meter Adjustment tower because the adjustment allen wrench screw was stripped(?) and he could not make mixture adjusts, he said. After the removal he made the adjustment to the internal air mixture screw, but the car has never run correctly (idle hunting/stalls). So I bought a new Air Flow Meter Adjustment tower and installed.
Unfortunately while make slight adjustment both clockwise and counter clockwise, trying to get the engine to run correctly, while writing down each adjustment, a gust of wind came though and the piece of paper I had been using was gone.
The question? When you have no idea what the correct direction and number of 1/4 turns are needed to get back to where adjusting screw should be, HOW do you start from scratch and get there? Example; with a normal carburetor you just bottom out the screw and back off, say, 3-complete turns. But I have seen nothing close to that concerning the Mercedes.
There is no Mercedes mechanic for 60 miles and that one already cost me over $500 to only have the same problem, and the next closest one is over 125-miles away. And of course the car is not starting now.
So I have to do the work myself, and only have the basic metric tools, and a RPM/DC Volt/Ohm meter. Any suggestions will be greatly appreciated.
Unfortunately while make slight adjustment both clockwise and counter clockwise, trying to get the engine to run correctly, while writing down each adjustment, a gust of wind came though and the piece of paper I had been using was gone.
The question? When you have no idea what the correct direction and number of 1/4 turns are needed to get back to where adjusting screw should be, HOW do you start from scratch and get there? Example; with a normal carburetor you just bottom out the screw and back off, say, 3-complete turns. But I have seen nothing close to that concerning the Mercedes.
There is no Mercedes mechanic for 60 miles and that one already cost me over $500 to only have the same problem, and the next closest one is over 125-miles away. And of course the car is not starting now.
So I have to do the work myself, and only have the basic metric tools, and a RPM/DC Volt/Ohm meter. Any suggestions will be greatly appreciated.
Thread Starter
Junior Member
Joined: Jun 2012
Posts: 40
Likes: 1
1985 Mercedes 500 SEL
Update on air flow control adjustment
Well I made adjustments about 1/8 turns clock-wise until the car finally started, then turned screw in tower CW until engine started to run rough, then back until it started running rough in the CCW direction, then found a happy medium in between. Engine now starts and runs ok, revs smooth with good response.
The engine idle ran a little rough until the Idle Control Valve came on, and this was only after the engine was warmed up a little. (have a little bulb connected to the two wires so I could see when it came on) When it did come on the engine idled much smoother, and dropped from 1100rpms to about 750. Does someone know why the Idle Control Valve would take so long to come on?
I notice one other thing that does not seem right. The fuel "Economy" gauge's needle, at idle, is not near the far left (black area) but instead is a little into the beginning of the red bar, just pass center. Anybody have a idea what is causing this, and how to fix it?
The engine idle ran a little rough until the Idle Control Valve came on, and this was only after the engine was warmed up a little. (have a little bulb connected to the two wires so I could see when it came on) When it did come on the engine idled much smoother, and dropped from 1100rpms to about 750. Does someone know why the Idle Control Valve would take so long to come on?
I notice one other thing that does not seem right. The fuel "Economy" gauge's needle, at idle, is not near the far left (black area) but instead is a little into the beginning of the red bar, just pass center. Anybody have a idea what is causing this, and how to fix it?
