ASR LIght coming on engine slows
 

Good afternoon, I have a problem the dealer can't figure out.

1994 E320 Wagon, intermitenly the ASR light comes on, whether cruise is on or not, the engine speed drops to 500 rpm , pushing on the accelerator pedal does nothing, and I have to turn of the the car and start it again which it does no problem.

Any help would really be appreciated.

RE: ASR LIght coming on engine slows
 

Hi,

Symptoms could point to anything, so need to narrow the field a little.

First confirm that the ASR and ABS systems work correctly for most of the time.
Are you SURE you know how these systems are supposed to work. Many people are unfamiliar.

If they are working OK (i.e. you can get the yellow triangle ASR light to come on when you try to spin the wheels on slippery surface) then this tends to alter the equation in favour of a power interrupt.

Suggest you change the Overvoltage Protection Relay OVP located in the electronics box under the hood.

The OVP supplies many ECU's (which would fit with the idle / lack of power symptom). however I would have expected ABS to go down also.

The OVP is not particularly expensive and do give trouble at high mileage due to manufacturing assembly issues.

The OVP switches the power OFF to voltage sensitive electronics in the event of an overvoltage episode. A faulty unit can do this randomly without the need for over voltage.

See if this solves the problem. let us know how you get on.

If not steal yourself for some serious fault finding.

Stuart

RE: ASR LIght coming on engine slows
 

Hi,

I can honestly tell you that it can by anything, that specific system is very integrated.
So it is a process of elimination.

In my case it was the airflow control unit. I don’t know what that specific part is called but it has a butterfly that controls the amount of air into the engine. It has a small black control unit on it. You can buy the unit separate I had to replace the whole part but got a good deal on a second hand part for a tenth of the price of a new part.

All the best,

Johann

RE: ASR LIght coming on engine slows
 

Hi,

You say that your ASR light came on because of a faulty MAF Mass Air Flow Meter?

The MAF will cause the Check Engine L CELight to come?

Please confirm.

Stuart