Between the 2 firewalls, next to the engine control module. It's sort of towards the center of the car near the battery. Look for the small module with the clear plastic lif on top, you'll notice the fuse under the lid.
Gilly

Thanx Gilly..........

Is the up rite rectangular aluminum box w/ the red top containing fuses, just to the left of the brake fluid reservoir,an OVP ?Attachment 66561

that's it...if you pull it out..and here a pebble rattle... your ovp is going or gone..

i always keep a spare ovp, fuel pump relay, and a klima relay around for our cars

Thanks Lee.....

Well, I had an interesting Saturday. I spent the entire day working on my car, and I found the problem. Whunter was on the right track - It turned out to be the idle air hose between the idle air valve and the cold start injector.

Let me tell you, replacing it was a complete *****. Ultimately, I had to unscrew the injector lines and pull the entire fuel distributor off in order to put the new idle air hose back on.:mad::mad::mad: It took me all day, because I tried everything to avoid pulling the fuel distributor before I gave in and did it.

Also - the aftermarket hose I got - from CRP I think is a poorly molded piece of junk that won't last two years. The two halves of the mold weren't even lined up making the thing uneven and giving it some VERY thin spots. I'm gonna have to do this job again soon.

During the process, I discovered much about the fuel system. I found out that I need two EHA o-rings, for starters.

Anyway, thanks for all your help everyone. The prize goes to Whunter. He was the closest. He said idle air valve, and it was just the hose luckily. BTW- I found that you can easily test an idle air valve with a 9v battery.

Tinypanzer, can you explain further about testing the idle air valve with the 9 volt battery? Thanx.....

Sure.....


Once you have the idle air valve out, you can look into it and see the little gate.

If you touch a 9v to the contacts, the gate goes clunk into the other position. It is supposed to require 12v, but mine was more than happy to click over with only 9v. So, if it fails the 9v test, I would quickly test it with 12v to make double sure that it really is bad.

If you blow through the valve as you are doing this, you will notice two different rates of air flow depending on the position of the gate.

You can visually see if it's going all the way to the other position. You can also visually inspect for crud that might jam it up.

I hit mine with a small squirt of carb cleaner which immediately removed the oil and dirt residue that had built up on the gate. I was careful to get it only in the valve portion of the device, and not to let it get in the motor part.

In the resting position, you see the gate and an opening on one side. With voltage applied, the gate moves so that the side that was open is now blocked and there is an air opening on the opposite side, where the gate used to be. This creates two different air flow rates.

I don't know much about how this is controlled by the ECU, and I have no idea weather it just lives in one of the two positions or if it switches back and forth constantly like a monovalve, for example. I would be interested to find out.

hey thanx alot tinypanzer........

You're welcome.....


One other thing I'm not sure about is if there is any "in between" position created by a varying voltage. No idea.

But, I was able to tell that mine was moving to both extreme positions readily and quickly, and therefore should be working just fine.

Or maybe you mean Gilly?

Gosh, you're absolutely correct, it WAS Gilly. Sorry, man! I should have gone back and read the post again, my memory is failing me in my old age!


Sorry, Gilly and Thanks! I guess you'll have to call Whunter and ask him to forward you that box of Cubans I sent him........ hehehe.....

I guess I can join your club of stalling, but it sounds like you have fixed yours. My 1988 300SEL was fine until the other day (last Tuesday), it stalled once and I just kinda shrugged it off as a one-time deal, but had my suspicions it was more problems to come. I drove the car Sunday and it did fine. I drove it again today and it stalled 3 times on my in a 25 mile trip. All three times was when stopping or turning. It runs smoothly otherwise and always restarts easily. When it stalls, all warning lights come on as usual. I have noticed a fuel smell under the hood over the past 4 weeks, which I am told could be the EHA leaking, but I am not sure if the stalling is connected or not. I hope my stalling is the OVP rather than that horrible hose you mentioned. The last thing I want to even think of is having to remove the fuel distributor.

I guess it dont matter, either way I will probably have to let the Mercedes shop fix it and charge me an arm/leg, because I am not a DIY'er at all unfortunately.

Why do I have the worst luck? I cant get ahead for car repairs/maintainence. Thats what I get for owning a MB I guess.;) Seems like everytime I turn around, something happens to one of my cars. Guess thats what I get for owning 18-21 year old cars. ;) Sometimes I just think I will go down and trade them in on a brand new car with a warranty, but then I would have a payment, which I dont have now.

edit - I saw you post on the other thread and replied. :)

I read that and thought WHunter may have mentioned the hose itself. No biggie either way, maybe he can send me one that says "It's A Hose!" on it (instead of It's a Boy or It's A Girl, OK bad joke, nevermind........)

Gilly