Please, M40 throttle stop-throttle arm gap

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DaniTD
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Post Wed May 27, 2015 8:13 pm

Hi,
We all know that on Motronic 1.3 equipped cars,t the throttle stop screw should not be altered. But, over all this years sure there was a mechanic that fiddled with mine, so I can't get my car to idle as perfect as it should. That's why I ask you to post here the throttle gap between the stop screw and the throttle arm on M40 engines so we can actually check the stock setting for the ones as me that have a messed throttle body.
Thank you :)
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Brianmoooore
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Post Wed May 27, 2015 10:14 pm

Unfortunately, it's not set to a specific gap. It's set by replacing the ICV with a dummy ICV with a fixed orifice in it, then adjusting the screw to set the engine at a specific RPM.
The method I use is to remove the ICV, block off both its hoses (or block the ICV and replace it), then adjust the throttle stop so that the engine barely runs, with an extremely low and lumpy idle.
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DaniTD
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Post Wed May 27, 2015 10:52 pm

The M40 has the 2 pin ICV. When unpowered, it rests at a fail safe position with a tiny bit opened. Shouldn't the engine run then when hot with the electrical connector of the ICV disconnected at the proper idle speed?
I'm fighting a low engine load I'm getting at idle when hot (1.5ms) when the specifications say it should be 2ms. I found no vacuum leaks so maybe the throttle is too closed and the ICV can't compensate? Also I'm having a low AFM reading (0.170) when specifications say it should be 0.2...0.3.
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Brianmoooore
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Post Wed May 27, 2015 11:05 pm

Sorry, missed the M40 bit, but the same still applies. With the ICV unplugged, I'd expect the idle to be below the correct value. ICV can only increase the idle speed, so it needs to be lower than normal when closed.