Sudden surge when decelerating.
 

Guys,
Anybody could give me a hint on why my car ,300E' 88 with manual transmision, having a sudden throttle surge when decelerating with the pedal brake pushed lightly and without stepping on the clutch. This happens all the times at about 2000 rpm to 1500 rpm. For information, I have a new OVP installed and working Microswitch (I checked) on the car.
Thankyou.

Guys, come on, no replies?
The problem is annoying because the sudden rpm surge happened for a fraction of a second caused the differential gear thumped and in the long run will ruin the propeller shaft rubber joint.
Thank you in advance.
Bye.

It may be the airflow meter potentiometer. Do a search on that, there's a lot of info on it in this forum.

kiato4,
thank you for u're kind reply. I do that. Found some threads on this air flow sensor potentiometer. Is it the short stem beside the air flow plate assy? Because I couldn't find anything with picture attached about this potentiometer.
tnx before hand.

Here it is.

To add, unplug the connector from the pot to see if the symptom disappears. Other driveability issues might occur then, but it's a useful test.

Steve

Does it happen just as you tough the brake, or does it happen at a fixed rpm as you decelerate? If when you touch the brake, you probably have a leaking brake booster.

If not, it's something with the fuel injection -- verify that the EHA current is correct and not ocsillating -- if it goes way negative (fuel cutoff) then bounces rather than going back to near zero, check the duty cycle and verify correct mixture, and check O2 sensor function. You could have a slow O2 sensor causing mixture flucuation on deceleration.

peter