My daughter's '96 C280 developed a problem overnight:

- it will start OK, but usually won't continue running
- sometimes when it is idling it will suddenly stop, just as if the ignition was turned off
- other times it will run OK

We were able to get to the gas station and fill it up yesterday, seemed to improve - but bad behavior is still there today.

When I was trying to start it today I stopped after 10 or so attempts and waited about 5 minutes. When I tried again, it started up OK with some initial fluctuation in idle speed that smoothed out in less than a minute.

Has anyone experienced a similar problem or have some ideas as to what the cause might be?

Thanks,
Forrest

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1W70PZW4N20Q13M4ZL&year=1996&make=MB&model=C-280-001&category=P&part=Overload+Relay

Do a search on OVP

Arthur, thanks for the reply. Search on OVP turned up some interesting possiblilties - including distributor cap/rotor.

Do try all of the electrical basics, like plugs wires cap,and rotor.be for you throw a bunch of parts at it.It is one of the first things people say to replace, the OVP.Now it dose run or supply a good number of Items so if it is bad you would have a host of symptoms.If you have the skill to use a volt meter you need to check several items, The on off ratio,The Eha, the pot, and the position sensor. Quite a few post on all those items. Good research, and good luck.JNT

There's no distributor cap or rotor on the car - so don't try to replace those.

No EHA, no rotor ..none of that stuff.
Your car is HFM/SFI , meaning full electronic with distributorless ignition.
All is controlled by an engine management ECU and that is powered by an OVP relay, which , in your case was a troublesome , faulty original part. Get the new part # and plug it in.
As I said , do a search to see if yours is original..if it is , replace
it first.

Thanks everyone - I realized soon enough that the '96 C280 doesn't have a dist cap/rotor.

I did examine the spark plug wiring and indiv coils - all of which it turns out are only about 1 year old.

The symptoms have changed a bit - or may be temp dependent. Once started, the engine RPM fluctuates from the real low 100's to slightly over 1000.

I'll also check the OVP part #.

-Forrest

Well, I replaced the OVP relay; still behaving badly. Decided to take it in to the shop. Barely made it, [Check Engine] light came on while driving there, stalled several times, etc.

I'll update with their finding$.

-Forrest

Mass Airflow Sensor

__________________
99 C43
98 S420
99 C230K
01 C240

Very possible ..

Codes would be a great help.

The reason for OVP suggestion first is b/c if the original part # was in there , it would give you the faults you are having and it has to be changed anyway as the origianl is a "Not If, but When" fail part. That is the reason for the modified part and new #. { you probably already read that in the archieves}

Autozone does do free code retrieve , if there is one nearby...

Don't have any codes as yet, will request them tomorrow. Where can a find a code description list?

-Forrest

if CEL comes on then it might be a whole other issue than OVP....

the thing about OVP is that sometimes the CEL is not powered and ECU gets bad voltage and acts erratically causing stalls.

there's also this other sensor thing on the intake tract with 2 metal tabs on it, what does that do?

Your car is OBDII - the code reader should read out the code description. If not, google OBDII to find a list of codes or post here.

Generic OBD2


http://www.obdii.com/codes.html