Bmw 3.0Si D-Jet Bj 1974 - fine tunning

Hi Antonio,
you asked for the throttle valve.

Yes, it must be totally closed.
The screw of the valve is just 'turned by' to prevent the flap from working into the housing.
But you must readjust the throttle valve switch after that.

Maybe someone turned the throttle valve screw before, and you adjusted the switch to this new, false position.

Regards
Norbert

- I can't localize the screw for adjusting the idle speed in your photos. Maybe Volker can help - he owns the Bosch manual for BMW, too.

Hi,

the idle screw is located on the foot of throttle below throttle switch. I have attached a picture of it. Normally you find this in Bosch's wortkshop manual . Unfortunately it does currently (?) not exist in English for your car, only in German. They also describe there how to adjust throttle flap so that if closes fully. But normally that stopper is sealed and no one touches it. Only idle-run screw is changed to adjust idle-run to 850 - 1000/min.

Only when you fully close idle-run screw and engine speed is still at 1200/in, follow my instructions above to verify other sources of excess air.


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Hi Antonio,

when you tell your story of 5 MAP sensors to have one running, this sounds familiar. Type 2 MAP sensors with full-load diaphragm normally fail over time with a torn diaphragm. I had recently bought one on eBay to have an additional reference and of course it was leaking. Seller was not even willing to give a discount (I was willing to repair myself), so I returned it. Hearing that Bosch charges something like 400 to 599€ for repair, he believed it was very valuable.

There are other gossips that one should use the cheaper 0 280 100 111 instead. But that is a type 3 sensor form MB 280 engine and it will of course not fit.

My proposal for an easy test: Draw vacuum and see how quickly it will fall. If it leaks, it is broken. If it keeps vacuum and screws or rivets are still okay (sealed), then it will be okay in 95% of cases.

Wow! Never saw that screw marked with red arrow!!! Neither the "thing" marked as "3"!

I'm running to my garage to check it out!
With expectancy...

Well,

screw 3 is the most important! That's where you adjust fel pressure to 2,0 Bar. 1 and 2 are the ones to loosen and turn throttle switch.

Antonio,

maybe it would be best to contact Bosch Automative Tradition and ask for the English version of the BMW workshop manual D-Jetronic. And if not available, maybe you can find someone to translate it from German. It a very valuable manual to have.