OVP Relay : Should I Bother? - PeachParts Mercedes-Benz Forum

cunix · #1 04-14-2006, 05:10 AM

Hi Guys,

Ever since I bought my 190E over 4 years ago, I did tried removing the OVP (out of curiosity) while the engine is running. There is no difference in the idle as opposed to my mate's car (also a 190E) where the RPM drops to around 500 RPM, and the engine shaking violently.

But my car runs great though...Performance and fuel consumption as per normal spec 190E.

The question is....Should I bother???? Is there anything I should check??
Anyone with same experience? Care to comment?? And...oh the fuse on top of the OVP is good though...

Thanks guys.

donbryce · #2 04-14-2006, 10:03 AM

You don't say what the problem is....is it the idle? If it ain't broke, ....

sbourg · #3 04-14-2006, 10:07 AM

With the OVP removed, your car will have no power to the FI computer and certain other control circuits. That means it will run open circuit, fail-safe mode. Emissions will likely be high, and driveability will suffer. If you are noticing no difference, your mechanical adjustment is probably slightly rich, and you will fail any smog testing. Cold weather problems will occur too.

OTOH, you should check if a PO has already jumpered around the OVP.

Steve

Duke2.6 · #4 04-14-2006, 10:43 AM

All the cold start enhancements are built into the electronics, so with no OVP the engine may not cold start or only with great difficulty.

Since the OVP provides power to the ABS, if it fails the ABS light will be on, which is a telltale sign of OVP failure.

If it works, there's no point replacing it, but keeping a spare handy is a good idea.

Duke

lkchris · #5 04-14-2006, 12:00 PM

Why don't you need overvoltage protection?

cunix · #6 04-18-2006, 06:18 AM

Quote:

Originally Posted by sbourg

With the OVP removed, your car will have no power to the FI computer and certain other control circuits. That means it will run open circuit, fail-safe mode. Emissions will likely be high, and driveability will suffer. If you are noticing no difference, your mechanical adjustment is probably slightly rich, and you will fail any smog testing. Cold weather problems will occur too.

OTOH, you should check if a PO has already jumpered around the OVP.

Steve

Thanks for the feedback guys.

I have to agree with Steve's comment.
I strongly believe the car is running on fail-safe mode.
Maybe the previous owner adjusted the air fuel ratio to slightly rich, and as
I live in a tropical climate, that explains why I have no cold start problem.

BTW Steve, care to elaborate more on how to check if a PO has already jumpered around the OVP??

Thanks all...

cunix · #7 04-18-2006, 06:21 AM

Quote:

Originally Posted by Duke2.6

All the cold start enhancements are built into the electronics, so with no OVP the engine may not cold start or only with great difficulty.

Since the OVP provides power to the ABS, if it fails the ABS light will be on, which is a telltale sign of OVP failure.

If it works, there's no point replacing it, but keeping a spare handy is a good idea.

Duke

Oppppssss...Sorry, BTW Duke, mine is a 1985 model without the ABS...

sbourg · #8 04-18-2006, 08:14 PM

Quote:

Originally Posted by cunix

BTW Steve, care to elaborate more on how to check if a PO has already jumpered around the OVP??

I believe the OVP has a diagram on its side, showing the output pin. If there is 12V at the socket where that pin goes in with OVP removed and the engine running, the OVP has been bypassed.

Steve