car apart right now-little help-idle swich adjustment?

[hcoles]

I thought this was going to be easy....
adjusting the "height" of the idle switch to be switching at 1 degree or rotation from the idle stop.

I find that the switch is riveted to the bracket and the bracket is attached to the tb with phillips screws facing toward the FRONT of the car... the only other way to adjust that I see is to bend the tab that lands on the switch...

any ideas here? You can sort of see the black rivets holding the switch.

Thanks.

[hcoles]

ok, thanks for the help... It can't be done very easy with the bottom of the tb in the car. I now have it out and will take some pictures. It looks like either I moved things when did the top end or as things wore.... the "setting" got off.. It looks like I really don't have much movement before the switch changes state.... stay tuned..

[hcoles]

FYI the radius to calculate the stop gap feeler gauge is 24mm.. this is used to calculate 1 degree. The spec. I think says to not be over 1 degree... so I think I'll aim for 0.8 degrees... calculations to follow...

[hcoles]

I took the throttle body off and got the thing on the bench.

The gap at the stop to activate the switch was 0.005 inches.. it should be about 0.014 inches per the spread sheet below. I readjusted for a feeler gauge of 0.014 inches in the stop to get the switch to change states.

I really can't imagine doing this with the tb in the car.

Here are some pictures for future reference or comments.





angle view showing rivets holding switch on.. not the adjustment point.




calculations to estimate feeler needed at throttle stop, the idea is to be a bit under 1 degree..



shows how far down I disassembled engine

[hcoles]

car is back together and running. I found that a feeler of 0.005inches was the switch change point and I changed it to be 0.014inches per the chart above to hit 1 degree.

idle is more stable and seems to be able to be driven slowly without bucking.. there is a bit of surging but the O2 sensor is still unplugged.
For some reason the idle now indicates 880 on the tack and it has never done that...I've always wondered why and assumed the tack was off. Somehow changing the idle switch adjustment fixed the bucking and raised the idle speed to what it is supposed to be...
I also found out the WOT switch wasn't working and I put in a new one.
All in all mission successful.

What a PITA to adjust this... but has so far paid off.

I have a Visio drawing I did for this and can put all the images/drawings here in one place if people show interest..

[scarceller]

Henry,

I just looked up that micro switch and it seems to come complete with the bracket, part number is 911-606-013-00 and cost about $75.00

I guess someone may have altered this in my car and mounted the switch with hex allen screws, maybe they drilled the rivets out.

I also see that my bracket does indeed adjust as well.

You are also correct that the adjustment procedure says that at NO more than 1degree off idle stop the switch must open. I found that spec in the Motronic DME Test Plan. The question is how much of a feeler gauge is needed to move the idle stop 1degree? and you calculated about .014" (.35mm) but somewhere I recall reading 1mm which is about .04", just can't recall where I read this but if your calculation of converting 1 degree to .014" (.35mm) are correct I would tend to agree and use that value since the Motronic manual clearly states 1deg.

I'm going to recheck my setting in my car now, I think I'll try your suggested .014" setting.

Thanks for the info.

[scarceller]

Henry,

Getting the WOT switch working is a very good thing, since without it working (always opened) the car would never get into the WOT fuel maps which are much richer than the mid-range maps. You should feel the improvement at WOT in the seat of the pants.

Originally Posted by hcoles

car is back together and running. I found that a feeler of 0.005inches was the switch change point and I changed it to be 0.014inches per the chart above to hit 1 degree.

idle is more stable and seems to be able to be driven slowly without bucking.. there is a bit of surging but the O2 sensor is still unplugged.
For some reason the idle now indicates 880 on the tack and it has never done that...I've always wondered why and assumed the tack was off. Somehow changing the idle switch adjustment fixed the bucking and raised the idle speed to what it is supposed to be...
I also found out the WOT switch wasn't working and I put in a new one.
All in all mission successful.

What a PITA to adjust this... but has so far paid off.

I have a Visio drawing I did for this and can put all the images/drawings here in one place if people show interest..

[hcoles]

To Sal and maybe others now or in the future...I found some sloppy trigonometry on my part. The 0.015inches should have been about 0.019inches. People are using up to 1mm feeler gauge without issues... the 1 degree spec. is probably fine with all items new and "perfect" in the car.

I think the important thing as mentioned by Sal... that the switch does not bounce up with your foot off the pedal.. this will be different in different cars depending on the condition of the motor mounts (esp. the trans. side) and linkage adjustment under the car near the "bell" crank. When the switch bounces I'm guessing some sort of nonsense is sent to the DME causing the ICV to receive "jerky" signals on one or both sides of the grounding poles. The ICV jerking or surging can be of frequency matching the natural frequency of the car momentum... causing bucking or surging.. this is what I'm tracking down. I'm still not to the bottom of this.

here is a more complete picture showing the geometry as I see it.
Note - don't adjust the throttle stop - shown with yellow paint. You are adjusting the "height" of the idle switch.





if interested in following or checking my calculations...here they are
I feel like an idiot for posting slightly incorrect info. and hope it didn't affect anyone's car.