Hey guys,

We have owned our '88 300SEL (M103 engine) for many years (it was my car for a number of years and now it is my moms car) and have really had no trouble out of it, so we have been very pleased with it. However recently something is going on that needs to be addressed pretty quickly.

On "hot start-up" the engine RPMS will race very high, then go back down. It seems to be getting worse and more often. I had to drive the car today to pick up some parts for one of my other cars and had to make two stops. When I got back in the car and started it, the RPMS went to around 3000 rpms then shot back down to normal. I had to make another stop and got in and it initially raced to 4000 RPMS! People were looking like I was crazy and trying to blow the engine. Other than this, the car runs fine and very smoothly. No changes in that aspect.

I have no idea what is going on, but any information would be greatly appreciated.

Thanks!

Check ovp relay fuse

I will do that, thanks.

Is this located in the main fuse box?

Thanks!

Its located behind the battery, you might have to take the cover off to get to it. If the cover is still on there. Also check the throttle linkage, gas pedal. Fuses. Check the basics

See -> overload protection relay also known as OVP - overvoltage protection relay in the link below.

1988 Mercedes-Benz 300SEL Base Sedan - Switches, Motors, Relays, Fuses & Wiring - Page 5

A small door on top flips up providing access to blade fuses inside. There are usually 2 fuses, although earlier versions of this has only 1 fuse.

Thanks a lot! So if the fuse in this is blown, I will need to get a new one rather than replacing the fuse in it?

I will look for it tomorrow. Thanks!

When I have experienced a failed fuse it in, the ABS fault lamp is usually illuminated.

Have you manually checked the linkage? Perhaps the accelerator pedal is broken? Happens often on older W126s.

Is the heater core bypassed? That hose can cause the linkage to catch upon it.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

Yeah, the ABS light sometimes illuminates because there is something wrong with a wheel sensor. ABS sometimes wants to activate for no reason. I have actually wanted to take the fuse out of it so that is just has regular brakes until we can get it checked. I guess my MB mechanic will be the only one to be able to check it. I am sure it take a computer to check it that somewhere like Autozone would not have.

The accelerator pedal was replaced with a brand new one purchased from this website about 3 years ago. It was sticking when you would press it. I don't think this is the case again because it only does the high revving when you first turn the key when the engine is hot and runs fine when driving and same as normal. Heater core not bypassed, heating/ac is fine.

I will check for a fuse in that OVP thing asap.

Thanks.