OVP help,, simple question - PeachParts Mercedes-Benz Forum

allenbistany · #1 08-27-2009, 05:38 PM

I know there's a lot a treads for ovp issues, but i can't find one specifically for me. My 89 300E is running like GARBAGE right now. It has the roughest idle all the time when i stop at a light, the dash starts shaking and everything vibrates. It hardly ever dies though, maybe like once parked on a hill when i first started it. THen when i drive it acceleration is so messed up. I'll floor the pedal and i wont go anywhere then i'll let off a bit and it'll start climibing. Ive gotten pretty good at brake torquing constantly. Also i wanna ad that the other day i was coming home and the ABS light came on, then flickered, then the engine light came on for like a second then shut off. Currently no warning lights are on. So OVP or something else?

bsmuwk · #2 08-27-2009, 05:51 PM

OVP are notorious for doing these sorts of things. I'm sure you've read this already, check and change the fuse on top of the relay. If you have someone with a similar car that works, try their OVP relay out. Only takes a few minutes to swap out.

tinypanzer · #3 08-27-2009, 06:18 PM

Yeah, the engine and ABS lights and cruddy running are classic OVP symptoms. Your motor is running with no computer, a testament to the overall design of the thing. I don't know too many cars other than that vintage MB that will run without an ECU.

Check the fuse on top, and pull it out and inspect the blades. I have seen OVPs with burned up fuse contacts, while the fuse was fine.

Swapping it out for a friend's will be a good test. It's a quick and easy swap.

allenbistany · #4 08-28-2009, 09:21 PM

i already looked at the fuse its not burnt and the contacts look like in good shape. Now my mom has a 91 300E you think i can try her relay. Is tehre a difference between 89 and 91 ovp relay, because i really dont want to wreck her car. Also any steps for taking the ovp relay out? thanks

Cal Learner · #5 08-29-2009, 08:12 AM

Same OVP in both years.

allenbistany · #6 08-29-2009, 02:44 PM

Alright mine in the 89 is very loose, all i have to do is pull off the electrical contacts at the bottom?

bsmuwk · #7 08-29-2009, 09:26 PM

If it's the same as my 300CE, there should be one metric hex head screw that's holding it in place. Remove that screw (however big it is) and lift up on the OVP relay. It's a very simple thing to do that takes about 5-10 minutes each.

dlevitt · #8 08-29-2009, 09:39 PM

On my 300E, the 'ears' on the OVP fit into a bracket without using other fasteners. It just tilts [only one way] until one ear pops free, slide it to the side [to clear the other 'ear'] and lift out.

cliffmac · #9 08-29-2009, 09:44 PM

just tune the engine up...if the OVP or O2 sensor are bad they will trip the check engine light on the dash...throw some new plugs and a rotor and filters at it and see what happens. I swear, everyone thinks this too far through...just start at the beginning...tune it up....you would have to do that anyway regardless of something more serious....the OVP is much overrated as far as a problem area...classic

lorainfurniture · #10 09-02-2009, 09:38 AM

I had the same ABS light and then flashing check engine light... I suspected my ovp for months now. Was never able to catch it in the act.. Finally just changed it, 3 days, and no symptoms..

Plugs and wires may cause some symptoms, but the abs light would lean me towards the ovp or elsewhere.

Rafi · #11 09-02-2009, 01:12 PM

I have never dealt with OVP. What years and Models have OVP ?

ps2cho · #12 09-02-2009, 08:04 PM

If the ABS light is on and your ABS is functional -- It's the OVP. I've never heard of the light come on for any other reason. I had it on for BOTH of my w124's I own. 300TE required a brand new OVP, 260E just needed a new fuse for it.