Emergency! Strangest thing EVER.

[Sulaco]

Well, I got most of my problems taken care of, except my voltage regulator, wiring harness, and MAS/O2 sensors.

Starting yesterday, I can't fully accelerate. If I floor it, the RPM's climb and it takes off as normal until about 3k or 4k RPM's (usually 4k) and the power just DIES. The engine doesn't die. It acts as if I've manually geared it down to whatever lower gear it's in and then let off the accelerator.

It's the most screwed up thing I've ever heard of. Ever.

I floor it to pass someone going about 50. It gears down to second gear and throws the throttle to get around, and almost as soon as it gears down, it just stops.

I put it in 2nd manually at about 30, then floor it (as a test). It climbs and climbs as normal but then gets to that point where it just quits and starts falling back down as if I'm not even hitting the pedal. If I just hold it floored and wait, it will eventually get low enough and start accelerating again. But then repeats the whole process.

Same day. My ABS doesn't work. The light on the dash is on most of the time. My rotors, pads, master cylinder, speed sensors, brake lines are all ok. A dog ran out in front of me at 55mph and I slammed on them. All 4 wheels lock up completely and I skid all over the road. I really wish I had skidded off the road and into a fucking tree (escaping unharmed).

Same day. Radio stops working. Moreso; the amplifier doesn't work. I turn it on, the radio comes on, antenna extends...no music. Sometimes when I'm stopped the music will come on. The second I release the brake and take off again the music dies.

Same day. My windshield wiper is going so fast I'm afraid it's going to fly off. I'm not kidding. I stopped driving in the rain today to avoid it becoming a launched projectile.

I'm sorry for posting so much, but this is outright fucking ridiculous. If this turns out to be some huge terrible calamity that it's going to take oogles of money to fix. I am seriously going to fucking destroy this car. Then you guys don't have to worry about me clogging up this forum anymore.

Edit: Some spelling and grammar errors. Was SOOO pissed when I wrote this.

[97C28O]

Looks like your car doesn't like you much :)

I don't know whats going on but I would suggest you get someone or the dealer or something... to take a look at it.

[jnenad16]

My guess would be a bad OVP relay coupled with a extremely high voltage output of your alternator. check those things first. nearly the same things happened to me on my C280, I checked the voltage, it was around 16V! so I replaced the OVP relay and the alternator and it fixed it all.

nenad

[Abuimad]

well i doubt its mechanical its something electrical...or maybe ur car is just possesed..i suggest u take it to some very good electrician or excuse me for saying the next word....or to the DEALERSHIP..cause sounds like u good a hell of a problem and its no joking matter (u already killed 1 dog)

[Sulaco]

Whew. Voltage meter says the battery is at 13v. So check.

But the voltage coming TO the battery when the engine is running says 16v. That's as high as the needle reads.

I replaced my OVP about 3 years ago. What indicates that it needs to be replaced?

If the alternator is OVER charging, then doesn't that mean that I just need a new voltage regulator?

I'm ordering the regulator asap. It's the cheapest, easiest place to start.

Thanks a MILLION nenad. <3 <3 <3

[jnenad16]

Originally posted by Sulaco
Whew. Voltage meter says the battery is at 13v. So check.

But the voltage coming TO the battery when the engine is running says 16v. That's as high as the needle reads.

I replaced my OVP about 3 years ago. What indicates that it needs to be replaced?

If the alternator is OVER charging, then doesn't that mean that I just need a new voltage regulator?

I'm ordering the regulator asap. It's the cheapest, easiest place to start.

Thanks a MILLION nenad. <3 <3 <3
you can start with the voltage regulator, and hopefully that will fix it. if it doesnt, alternator and the OVP relay are next on the list. but do it as soon as possible, or dont drive the car before you fix it to prevent the battery from frying.

nenad

[enawazh]

hey guys this is my first post. ive been taking my time to read through the forum topics and i came across this topic. i have a 95 c280 and have the exact same problem with the power loss. the car revs hard but when it hits 4000 it just chokes and looses power forcing me to lift off the pedal. i have 145000 miles on the car. recently changed the whole wiring harness (old one crumbled in my hands) but the problem is still there. my MB mechanic told me it could be a vacuum leak in the system, bad ignition wires or coils.

what i did figure out is that if the turn off the car put it in park and start it up again the problem goes away.( revs right up to 6)
Whats up with that?

[Sulaco]

enawazh: I just fixed that particular problem. It was my voltage regulator.

I installed the new voltage regulator yesterday. I'll see if I can post a quick DIY.

1. Open hood, remove top of airbox (disconnect it from the MAS also) and place aside. Remove air filter. Now you can get to the alternator with ease.

2. DISCONNECT BATTERY. SERIOUSLY.

Next simply involves removing the back plastic cover on the alternator which is HARD given it's location. So here's what I did.

3. Disconnect the 2 wires connected to the back of the alternator. One has a plastic cover over the nut you must remove first. Simply use a socket wrench. They were 2 different sizes and I can't remember which they were.

4. There are four 8mm bolts holding the back of the alternator (core and all) to the pulley side. I used a small ratchet with an extension to remove them. You can only see 1 of them, the other 3 you have to feel to find (not hard). Remove them and use a flathead to pry the back of the alternator free. It should fall free. Grab it and be gentle with it. There is a plastic spacer ring inside it you MUST preserve. (I actually broke mine. But since it's not an important friction-baring device, I super glued it back together). Lower the entire alternator down through the bottom of the car. It might take some pushing, but it will fit.

5. With the entire back of the alternator out; remove the 4 phillips screws on the back of it. Pry up the 3 plastic snaps holding the plastic cover on. I used toothpicks to hold 1 out while I moved to the next one. With all 3 snaps held out, use a flathead screwdriver to pry the cover away from the metal housing. After some persuasion, it will start to come free enough to just grab and pull with your hand.

6. You can see your old voltage regulator now. Keep a VERY good eye as to which way it is installed. Remove it. 2 Phillips screws. DO NOT install your new one yet. The new one has to be installed with the core installed to the pulley shaft, so you have to bolt the core back onto the pulley assembly before you can install your new one. We only removed the core from the car to greatly reduce the time it takes to remove that black plastic cover.

7. Leave the back cover off and put the core back up underneath the car and push it back up in the engine bay. Get back up top and be careful to place that plastic ring back inside the alternator core. There are 3 possible ways for it to go in. Just line up that tab on the plastic to one of the 3 holes for it in the core. Line the core back up on the pulley assembly and push it up as far as you can. It won't slide on the whole way, because that plastic ring needs some pressure to get back on tightly. I simply put it on as best i could with my hands then slowly bolted the entire core back on the pulley assembly using 2 of the bolts on opposite sides. Go ahead and put all 4 bolts back on as tight as you can.

8. Install new voltage regulator. Make sure you have it on the right way. The metal hook piece on the side should be facing the alternator and not facing the back of the engine bay. Attach the 2 philips screws holding the old one on.

9. Slide the plastic cover back into place, snap it on (mine took a few taps with the screwdriver), screws back in place, attach wires again. Assemble air-box again. Double check to make sure you didn't miss anything and no tools are left under the hood.

10. Connect battery. Crank!

I had a friend stand by with my hood popped for the first crank to make sure nothing crunched or shot sparks :)

Completely fixed that death-at-4krpm's problem. Now I can floor it in any situation and she's as good as new (except for that rough performance at low idle, but that's something else). Fixed my ABS. Fixed my abnormal brightness/speed of various features. Fixed the dimming of the gauge lights. Fixed my radio/amp. Fixed my bouncy idle when I first crank it.

Total cost: $34 (includes shipping and handling).

[martattack]

I agree with Sulaco. SOunds like your voltage regulator isn't regulating anymore. Those Diodes wear out eventually and your car will start doing some crazy stuff.

The fact that it happens at a certain RPM is what kinda gives it away as being an alternator/voltage regulator problem.

[enawazh]

thanx a lot for that write up man.
i honestly havent gotten to it yet but im gonna try to get that fixed as soon as i can.
seriously guys thanx for the help this has been driving me crazy.

[Sulaco]

No problem. Don't let the length of that write-up scare you. It's such an easy job. But nothing I write is capable of being "quick" and "to the point."

DO NOT pay someone else to do this for you.

[CMSw202]

thanks for the write up. i just received mine in the mail yesterday. i will be installing it today.

[CMSw202]

i finally installed my VR today. i followed the instructions but i wound up tossing them once i got to the point where i had to remove the bolts on the pulley side. i couldn't find where the other 2 bolts were so i said screw it. i wound up being able to remove the plastic cover easily. there were only three screws on mine and the tabs were easy to unlock. once i had the screws and the tabs disengaged all i had to do was pry off the cover and there was my old VR. i took the thing out and man was it worn. my car runs a lot smoother now but i still have to do a bunch of other stuff to it. i think i have a vacuum leak, and i might have to replace my MAS. Thanks for the write up. it was a lot of help.