I am having some problems with my 1991 420 SEL.

Previously, it had a high idle, approximately 1,400 RPMs when warm. The dealer found some bad wiring around the EZL unit, after the wiring was repaired the idle now appears "normal" and is about 800-900 RPMs when warm.

Here the new problem: when traveling down the road, and I start to slowly back off of the throttle, I reach a point where if feels as if the engine abruptly seems to die - like I let off of the gas really fast even though I didn't (it doesn't actually die, but if sure feels like it). I am assuming that this is an abrupt transition to "idle". When I ease on the throttle again, I can feel it transition hard again as if the engine is now back on. I hope I am explaining this clearly. It doesn't do this every time I let off of the throttle (sometimes it is very smooth even though I let off fast), and it doesn't do it that I can notice with the car in park or neutral, only traveling down the road.

Acceleration is good, and I notice no other symptoms other than the hard transition from letting off of the throttle and applying throttle? The idle is not erratic, although it does seem to vary a little between 800 and 900 RPMs.

Could this be the air slide valve sticking or not functioning properly; if so can this be cleaned or does it need to be replaced? Additionally, I found some info regarding the overflow voltage protection relay (OVP), could my problem be associated with this as well?

Any help or suggestions would certainly be appreciated.

Lee
1991 420 SEL
Lee.Jones@aspect.com

I would have the idle switch checked to make sure the adjustment is proper. Also, I have seen the airflow meter do the same thing.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS