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Last night I attempted the Throttle Body Adjustment procedure on my 1977 530i. As I was down to the end of the adjustment I discovered that I have the single throttle switch instead of the dual switch setup that the document had. I read through some other information in my Chilton book I found that I could measure the three contacts on the single connector to measure the resistance. The closed throttle position read correct with an almost zero resistance, but when I open the throttle all the way on, I did not measure any resistance on the other contact. Does this mean my switch is bad?

I am trying to resolve a lurching and a bogged down problem. (lost its zip)

Any help would be appreciated.

Steve

SteveinSLC wrote:Last night I attempted the Throttle Body Adjustment procedure on my 1977 530i. As I was down to the end of the adjustment I discovered that I have the single throttle switch instead of the dual switch setup that the document had. I read through some other information in my Chilton book I found that I could measure the three contacts on the single connector to measure the resistance. The closed throttle position read correct with an almost zero resistance, but when I open the throttle all the way on, I did not measure any resistance on the other contact. Does this mean my switch is bad?

I am trying to resolve a lurching and a bogged down problem. (lost its zip)

Any help would be appreciated.

Steve

It could be dirty. Pop the cover off and watch how it works. Very fine sandpaper VERY lightly stroked can clean off any oxides, once you verify the contacts are physically closing at WOT. But that only gives you the extra fuel when you floor it.

You should check the entire throttle body adjustment, leaving the switch adjustment for last.

Note if you've upgraded fuel injection to 528i style, your old throttle switch won't work that well.

Yes, but in my experience the WOT (wide open throttle) isn't really that important, it doesn't seem to make much difference. If you can pop the cover off, and I think you can on those, clean it up as Peter mentioned, but don't sweat it if you can't.

Any ideas on the lurching and bogged down feeling?
I have done the Throttle adjustment along with a timing adjustment and also replaced all the spark plugs.

Any help would be appreciated.

Steve

SteveinSLC wrote:Any ideas on the lurching and bogged down feeling?
I have done the Throttle adjustment along with a timing adjustment and also replaced all the spark plugs.

Any help would be appreciated.

Steve

sticky or worn airflow meter

feel the door for any binding.

Also back-probe terminal 7 on AFM connector (pull boot back to expose connector shell) with voltmeter. Slowly push the door open and look for any drop-outs off-idle.