Very Difficult Cold Start
 

My '87 300E has recently developed a problem starting when cold. Sometimes it seems as though it will run on only a couple of cylinders and at other times it may take me up to 5 attempts to get it to even try to start.

Once it fires up it will run only at idle with a severe miss until the engine warms up a bit and then it runs normally.

I suspect a problem with the cold start valve. Can anyone shed some light on a possible diagnosis or suggest a test?

Thanks.

are your sparkplugs in good cond. and correct type? h-9dc or h-9dco
what grade gasoline? easier cold starts with regular.
is your engine using oil? possible oil fouled plugs
MF

Is your ABS lite on? The OVP relay will cause both symptoms or either symptom.

The cold start valve is unlikely to cause the engine to run poorly. It has NO function except momentarily while the starter is cranking.

Steve you are a guardian angel with greasy fingers. Yes my Antilock light is on and I can't get it to go off.

I'll order the OVP from Parts Shop right away. Wow... what a relief.

By the way... the Becker Radio that I got from your brother Scott at Continental Imports is superb. I especially like the short wave capability.

:)

Not To Seem Stupid
 

What is the OVP relay? Seeing as I recently purchased a '86 300E for the wife any info on these gas engines would be helpful.

Charles

Use the search mechanism. OVP is probably the single most talked about problem since I have been here.

The device is basically a surge protector for various important/expensive control units. It uses a zener diode to short all voltage over a set point to ground through the fuse.

Jump starting with a battery charger or other high voltage methods takes out the fuse. Alternator/regulator problems can take out the fuse/fuses. But, most problems are actually just defective electronics or circuits within the device. On a wide group of 201/126/124 cars the simultaneous incidence of cold start problems and ABS light are a good clue. I have had units that would power one and not the other controller though and I have seen enough intermittant internal connections to waste weeks searching.

I now replace any OVP with original date code if the car has any stalling or cold starting problems.