[Momo08]

You can try and replace the o-rings. That's what I did. In my case, that didn't work. And I bought a new EHA. And I bought like 10 of those o-rings. Because you can lose them.

Oh, and if you're new to MB, I'd suggest buying the EHA from fcpeuro. They have a lifetime warranty. And my EHA which is 18 months old just tested as "bad." So I'll be sending it back using that warranty.

And everyone will say don't buy a used EHA. I tried it. Didn't work. It was bad. Bought new.

So updating, I put new O-rings. Didn’t change much, except it is not idling as long as it was before. It starts idling really high and bouncing between 1000 and 2000 as if I was trying to rev it up but I’m not even pressing the gas pedal at all? I’ll definitely have to get the new eha, but was wondering if the symptoms meant anything?

 

[Former Repair Manager]

it sounds to me like you could have a burnt out transmission I would check the color of the fluid if it’s dark or black the transmission is probably done and needs to be overhauled

 

[Momo08]

The transmission fluid is not dark or black but it’s not red or pink for that matter. Now, quick question, how does the transmission play into the cars bouncy idling? And can I do a transmission fluid replace or flush before doing an overhaul? Thank you for your input btw

 

[isthenew]

So updating, I put new O-rings. Didn’t change much, except it is not idling as long as it was before. It starts idling really high and bouncing between 1000 and 2000 as if I was trying to rev it up but I’m not even pressing the gas pedal at all? I’ll definitely have to get the new eha, but was wondering if the symptoms meant anything?

Is the EHA leaking gasoline? If not, there are other things to look at. And there's a way to test the EHA.

 

[Momo08]

It was pretty wet when I took it apart haven’t paid much attention after I put the new O-rings. I definitely would like to test it, although I’m ready to buy a new one from tcp as you mentioned.

 

[Momo08]

Tcp I meant to say. And do you have any links as to how to test the eha? Also, where else would I look if the eha turned up to be good or I get it replaced? Thanks

 

[isthenew]

To test the EHA, you're testing mAmps. You first need the engine at operating temperature. Then, you turn off the engine and unplug the EHA. Then you add your multimeter (set to mAmps) to the circuit. You restart the engine and check the multimeter value(s).

In my picture, you can see my yellow alligator clips run from the front EHA prong to the front connector on the wiring harness. Then you'll see the red alligator clip runs from the rear EHA prong (the prongs are numbered 1 and 2, but I can't remember which is which) to the multimeter. And the black alligator clip runs from the multimeter to the rear connector of the wiring harness. So, the EHA's front connection is normal, you add the multimeter to the second connection.

You'll need to verify what your value should be. I expect it will fluctuate just above and below 0. In my car, I think it's supposed to be 0.3 to -0.3.

There are great videos on YouTube by FixMyMercedes and MMWA on your engine. You'll want to watch them. MMWA has one showing the set up I gave you here. FixMyMercedes goes through all sorts of diagnosis techniques and repairs.

EDIT: It's FixYourMercedes

 

[isthenew]

Have you looked at the OVP? Idle bouncing like that is notorious for a bad OVP

 

[Bill SD]

Have you looked at the OVP? Idle bouncing like that is notorious for a bad OVP

Ditto..I mentioned that earlier....I tested mine, one of the circuits was bad, resolved a number of issues

 

[Momo08]

Ok, stupid question, where would I find the ovp in my car?

 

[Bill SD]

Ok, stupid question, where would I find the ovp in my car?

Its under the cover behind firewall on passenger side, you can test this before replacing blindly. I think there is a thread on testing it.

OVP - basic function and test

Mercedes OVP – A Basic Primer and Test Process I am dealing with my second failed OVP and reviewing the various links prompts me to try to consolidate some of the scattered information into this single format. I hope it is useful. See Figure 1. below for a picture of a typical OVP relay...

www.benzworld.org

 

[Momo08]

Its under the cover behind firewall on passenger side, you can test this before replacing blindly. I think there is a thread on testing it.

OVP - basic function and test

Mercedes OVP – A Basic Primer and Test Process I am dealing with my second failed OVP and reviewing the various links prompts me to try to consolidate some of the scattered information into this single format. I hope it is useful. See Figure 1. below for a picture of a typical OVP relay...

www.benzworld.org

good afternoon everyone, so I’m a bit confused right now as to this ovp relay. One, can someone explain to me why it has 9 prongs but it only connects to 6 of them? Two, the 2 10amp fuses seemed fine and not corroded, could this ovp still be the cause of some fo the issues I’m having? Thanks for all the info everyone has been sharing by the way. I’m not a full on mechanic incline person by I’m trying and I love the car and would love to drive some time in the near future with everyone’s help

 

[aam]

More pins?
Is two relays in one.
Same part for many...
Regards,
aam.

 

[isthenew]

You're going to want to verify the part number, 201 540 37 45, is the correct one for your car. The prong numbers might not match. For example, my fuel pump relay has extra prongs.

OVP's can test as good but still be bad.

 

[Momo08]

More pins?
Is two relays in one.
Same part for many...
Regards,
aam.

My mistake, yes, more pins. Actually 3 of them stay unconnected so I’m wondering if that’s actually normal

 

[aam]

It is normal.
There is also a single ovp that will do the job perfectly....
Regards,
aam.

 

[Momo08]

Good evening everyone, so things seem to have taken a turn for the worst. So after checking the ovp, and not seeing anything out of the ordinary wrong with it, I went ahead and installed the ovp back on it. At this time I go and crank the car and it won’t stay on. It starts and dies right away. I bought a new ovp, hoping maybe I messed it up some how, installed the new ovp and the car starts but dies as quickly as it turns on. I’m at a lost here. Seems I’m going backwards instead of forward trying to get this car to daily driver condition. Please help

 

[isthenew]

Let's get back to basics. Are you getting fuel? Have you tried jumping pins 7 and 8 on the fuel pump relay?

 

[Momo08]

No, the car used to start and stay on for a while before it just fine, before it would unexpectedly cut off. After the ovp issue, it starts and dies right away. Correct me if I’m wrong, I’ve looked for fuel pump relay location here and it shows me that there is no relay for my car. It’s points me to a box that looks more like a module. Is this the correct part? And if not, where is the fuel pump relay located on a 93 300sl? Thank you again

 

[isthenew]

No, the car used to start and stay on for a while before it just fine, before it would unexpectedly cut off. After the ovp issue, it starts and dies right away. Correct me if I’m wrong, I’ve looked for fuel pump relay location here and it shows me that there is no relay for my car. It’s points me to a box that looks more like a module. Is this the correct part? And if not, where is the fuel pump relay located on a 93 300sl? Thank you again

That I can't help with. Though I do believe my '96 SL320 had a fuel pump relay or something in the trunk, near the battery.