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Throttle Valve Switch Adjustment

3K views 8 replies 3 participants last post by  pdolan1953 
#1 ·
I've had help diagnosing my high idle problem and the bad part is the throttle valve switch. I have printed the instructions from the manual but I'm not understanding how to adjust the switch once its on the throttle valve. Per 07.3-152 it says to 2. check idle speed stop by pushing throttle valve to idle speed stop. 3. Keep turning throttle valve switch to 0 ohms is indicated. 4. Lift throttle valve slightly, readout to infinity ohms and insert 0.3 mm gauge. I guess I need some pictures or a better explanation. I'm not getting it. Thanks in advance for any help.
 
#6 ·
Ok, my intake manifold was off the car when I did my adjusting. If yours is on the car it may be tough trying to move the switch. Here's what I did. Set my ohmmeter to measure 0-infinity ohms. I used alligator clips to attach the probes to jacks 1 and 2 on the switch plug. With the throttle valve all the way against the speed stop I moved the switch till I got a reading of 0. Then I lifted the idle valve a bit and inserted a .3mm feeler at the idle speed stop and got a read out of infinity. It took a few tries of moving the switch just right to get these readings. Then to check for full load stop you connect to jacks 2 and 3 and push throttle valve against full load stop and you should get a readout of 0 ohms. Then moving the throttle valve slightly in direction if idle speed should give you infinity again. I hope this helps.
 
#9 ·
OK I'm back. My 450sl is a 74 so it's switch is different than 7.3-152 but that led me to 7.4-140 mine. It's too cold outside today to do the engine running part but I did take it off and gently popped the plastic cover off. Everything looked good, It has contacts that make and break connection as the throttle goes from idle to w/o. I slid a piece of paper between the contacts to clean and put it back on. I'll see how it runs when the roads get less icy. thanks again!
 
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