M117 engine: Throttle body plate

[bobboyer5]

People:

In messing with my K-Jetronic system, I started adjusting small screw on top that adjusts (I believe) the air mass sensor. Which controls opening of throttle plate.

anyway.....

The plate sometimes has very little resistance when motor off to depress, other times, much harder resistance.

What should I properly do, here?

[sbourg]

The accelerator cable and linkage control the throttle butterfly. The engine demand, in conjunction with the throttle opening, control the opening of the air flow sensor plate. I believe the airflow sensor plate is what you are calling the throttle plate.

Presuming this to be true, the plate could be gummed up with deposits - clean with a rag and rubbing alcohol or such. Also, there could be a problem with the fuel distributor requiring its service or replacement. Adjustments will not affect this, and could really screw up your mixture, if you are not monitoring.

Steve

[bobboyer5]

OK.

So...re: linkaqe connection: what do I have to look for, and how to adjust/remedy? What's a good test?

[sbourg]

The airflow sensor plate is in no way connected to the throttle linkage. The plate is opened by airflow only. It does not control the airflow into the engine. It 'reads' the airflow and mechanically connects to the fuel distributor to adjust the rate of fuel flow through the injectors to match the airflow rate.

The airflow is controlled by the throttle butterfly, which is another 'plate' further along in the intake. That one is connected to the linkage and connected to the accelerator pedal.

Steve

[jeffmg1]

As the sensor plate goes down it pushes a control plunger up. The control plunger meters fuel to the injectors. Fuel pressure is used as a counter force on the control plunger to prevent the sensor plate from moving to quick. With the pumps off the fuel pressure will decrease, and the plate will move easyer.