After searching some previous threads about my warm hard starting issue, many responses have said that it may be an OVP. What does that stand for and what does it do? Thanks.

Over Voltage Protection-relay, it protects the Innjection unit, ABS unit and so on from high voltage, if that relay is broken the car is hard to st5art and rattles a lot b'cause its going in "failure mode" without ignition settings and so on, the ABS/ASD and so on dont work either, The relay sits behind the battery by the units, its big and silver and has an fuse or to on its top depending on which model it is, the fuse on the ovp can be broken too, check that first!

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Patrik Nilsson -83
230CE -88
230TE -87
http://www.hastonnet.se/putte/avatar-new.jpg

Thanks so much for the reply. If this unit is bad or fuse is broken would is still run fine, just hard starting?

For your 88 300CE? It is behind the battery, under the plastic water shield. It is silver with a red top with a hinged cover on it.

It would not affect the car's starting preformance when warmed up however. Only affects cold start...

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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

The Overvoltage Protection Relay protects against both overvoltage, which might be caused by a charging system fault and overcurrent (the fuse(s)) if something that it powers shorts.

Since it provides power to the KE injection system ECU, the idle control components (including the throttle valve switch (TVS) and idle air control valve) and the ABS control module, the telltale signs of an of an OVP relay issue are hard starting (all the cold start functions are in the electronic part of the KE system), no idle speed control, and illuminated ABS light.

Though this relay is supposed to protect against a system overvoltage or a downstream short, the relay itself appears to be much less reliable than than the changing system or components it is supposed to protect.

Duke

The original relay, manufactured by Siemens in Austria, had defective solder joints. Needless to say, depending on which joints didn't complete a circuit, a whole host of anomalies could result. The replacement is far more reliable.

An actually, it's "hot starts" that are the problem, not cold, when the OVP is malfunctioning.

Other issues can be an ABS light illuminating on the dash even when the ABS is normal, and stalling at low speeds.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Pull out your OVP relay when it's cold and see if you can start the engine!

Duke