M-103: too many issues for the title... - PeachParts Mercedes-Benz Forum

400Eric · #1 12-27-2009, 06:22 AM

What's next? Now the car has developed some kind of battery drain that completely drains the battery overnight unless I disconnect it in which case it's still fine in the morning. To go along with this we now have an ABS light that is on all the time and a cold start problem that seems like the cold start injector isn't working (not saying that's what it is, cause I don't think that's what it is, just saying that's what it seems like.) It's VERY HARD to start now when it's cold. Also have lost all of my low end torque now even after it's warmed up. Anything up to about half throttle is fine, anything more than that and you have to wind the pee out of it to get anything resembling acceleration out of it. The car is really getting slapped around now a lot on the freeways and it sucks big time. All the other drivers think it's a diesel and they don't want to cut it any slack cause they don't want to be "stuck" behind a "diesel". So they speed up whenever I put the blinker on to change lanes (so I can get off the freeway or whatever) instead of letting me in the lane and I'm helpless to do any thing about it except drive like an a-hole and not announce my intention by turning on my blinker in the first place. It sucks. But the cold starting problem is the worst part...it's really bad. All of these latest issues have hit at the same time and fairly suddenly so I'm thinking they are somehow related. Thanks to all who help! (89 300E 3.0).
Regards, Eric

gsxr · #2 12-27-2009, 11:46 AM

Time to get out an amp meter, and check every circuit until you locate the drain. Connect the meter between the battery terminal and battery cable, you should see a draw of at least a half-amp, could be one amp or more (normally it's very low, maybe a tenth or less?). Now pull one fuse at a time until you see the reading drop to nearly zero. When it does, you've located the problem circuit. Then, you focus on that circuit and figure out what is causing the drain. Should be loads of fun!

Wild guesses: I think the cold start problem is because the seventh injector ain't working (it's an electronic injector, used for cold start enrichment only). The lack of power when warm sounds like the EHA circuit (electronic fuel control) also is not working. But, I don't know how to troubleshoot either item.... sorry!

johnathan1 · #3 12-27-2009, 12:45 PM

When the ABS light stays on, and the engine starts having trouble...that usually means the OVP relay needs replacing. That could easily be your problem.

Also, how much oil is your M103 burning? Mine was burning so much that it would foul the plugs after a little less than two months, and it would make it lose all kinds of power, hesitate like crazy, and made it VERY hard to cold start. I had to replace the plugs every two months or so until I finally sold it. New owner replaced the valve stem seals, and now all is well from what I hear.

JayRash · #4 12-27-2009, 02:24 PM

check the OVP and the fuel relay, if that doesn't work try another CIS ecu, IIRC u have another M103 W124 so just try its ECU, (not the EZL)
If all this doesn't work, plz check if the car is running rich (black smoke) or if it is lean, it can be the airmeter sensor that the cis plate is connected to, it is expensive to replace.

But i still say its an OVP or the relay with the red top that has 2 fuses in it for that controls the CIS/choke/ among other things.

junqueyardjim · #5 12-27-2009, 03:11 PM

You'll get more money for it at the P & P if you can carry it down there on that flatbed wrecker. Not many of us have that luxury nor the luxury of being able to park so many vehicles!

400Eric · #6 12-28-2009, 01:03 AM

It's not a luxury when you have to store some of them 75 miles away.
No need to get Festus involved. I may be pretty ticked (REALLY ticked actually) at this car right now but I couldn't do that. Not to a member of the family. I could send Benzer 1 to a new loving home but not to the junkyard. We brought our beautiful daughter home from the hospital in this car. At over 214,000 miles, this car gave me 136 MPH just for the cause of out top-ending a much younger Lexus GS just because it was something that needed to be done and was the right thing to do. This is the car that hooked me on Benzes and W-124s. That's why all of my subsequent Benzes are named after him. Nope, we have to fix him. Do you have any better ideas?

I was already running the 88's CIS-E ECU when these troubles began, and I had already switched back to the 89's ECU as of Saturday morning with no improvement in the situation. Good idea though Jay. That's why I've already tried it.

I'm going to try some more of the other ideas tomorrow and then check back tomorrow night. Thanks guys and please keep the ideas coming.
Regards, Eric

gsxr · #7 12-28-2009, 12:57 PM

I'll second the recommendation to replace the OVP, if the fuse isn't blown on it. After re-reading your post, I'm nearly certain that is the cause of the problem.

mak · #8 12-28-2009, 06:29 PM

OVP and fuel pump Relays ; seems like a common failure in these models and its age related.
mak

400Eric · #9 12-29-2009, 02:35 AM

OVP fuse was blown. It's really exasperating cause I just checked that about 10 days ago and about a month ago too cause I've been chasing several other issues as well (like the high idle problem I posted about here M-103 high idle). In that thread I spoke about how I had read many posts about OVP issues, but I didn't think that that problem was caused by the OVP (but I did check the OVP anyway just to be sure and the OVP was still good at that point.) So after having checked it a few times already, I didn't think to check it yet again. Johnathan1's post made me connect some dots though when he brought up the ABS light angle, that was something I didn't have before and that is something I see associated with OVP issues on the other threads. That's why I checked it yet again today. Thanks guys!

Any idea why the fuse blew? I'd like to prevent it from happening again. And how come my OVP only has one fuse not two?

All is not well though. I still have this battery drain issue that is pretty bad. I have confirmed the issue is still there by touching the clamp to the battery post and getting a pretty big spark out of it. It's a fairly noisy spark too I might add. Before I have to resort to GSXR's method (which I really don't have time for right now), are there known trouble areas/weak links where I should look first?
(BTW GSXR, I've already stopped the air leak in the trunk [it was the trunk lock unit after all] so no, this battery drain issue isn't from the pump running all the time.)

Also haven't had any aux. cooling fan action for a while. You can peg that temp. gauge and it still won't come on. Any known trouble areas/weak links I should try first? Thanks to all who help.
Regards, Eric

gsxr · #10 12-29-2009, 10:58 AM

Quote:

Originally Posted by 400Eric

OVP fuse was blown. ... Any idea why the fuse blew? I'd like to prevent it from happening again. And how come my OVP only has one fuse not two?

Either the fuse was old and weak, or something is drawing excessive current. Early OVP's have one fuse, later OVP's are a different design and have two fuses. They are NOT interchangeable.

Quote:

Originally Posted by 400Eric

All is not well though. I still have this battery drain issue that is pretty bad. I have confirmed the issue is still there by touching the clamp to the battery post and getting a pretty big spark out of it. It's a fairly noisy spark too I might add. Before I have to resort to GSXR's method (which I really don't have time for right now), are there known trouble areas/weak links where I should look first?

Sorry bud, what I described is the only method to pinpoint the problem. I supposed without a meter, you could pull one fuse at a time and see which one makes the Big Noisy Spark go away.

Quote:

Originally Posted by 400Eric

(BTW GSXR, I've already stopped the air leak in the trunk [it was the trunk lock unit after all] so no, this battery drain issue isn't from the pump running all the time.)

The pump has a timeout, so even if there is a leak, it will shut off after 30 seconds or so (unless the pump is bad, which is not a common failure).

Quote:

Originally Posted by 400Eric

Also haven't had any aux. cooling fan action for a while. You can peg that temp. gauge and it still won't come on. Any known trouble areas/weak links I should try first? Thanks to all who help.

The aux electric cooling fan on 1988-up models is controlled by the ACC pushubutton unit. It receives a signal from a temp sensor (not switch!) on the cylinder head, and above ~107°C or so, it triggers a relay which turns on the fan. Step one is to verify that the fan works at all - you can easily test this by shorting out the pigtails at the red or green switch at the AC drier behind the left headlight. If the fan doesn't turn on, check the fuse (external 30A strip fuse on driver's strut tower), then the relay, then the fan itself.

pesuazo · #11 12-29-2009, 03:19 PM

I have an OVP relay (came from working car).

If interested, $20.00 shipped

daddi · #12 12-29-2009, 06:41 PM

If your car were a horse i'd have him shot.

gsxr · #13 12-29-2009, 07:23 PM

Quote:

Originally Posted by daddi

If your car were a horse i'd have him shot.

ROTFLMAO!!! Ya know, Eric, he has a point...

ps2cho · #14 12-29-2009, 09:45 PM

For cold start issues it could be your accumulator if its not holding pressure overnight. Only way to rule it off is replacement, or to get a CIS fuel pressure tester. I doubt your Cold start injector is the issue. You can always pull it out and start the car and see if it is leaking or spraying any fuel at all.

400Eric · #15 12-30-2009, 04:47 AM

Daddi, GSXR, at the risk of repeating myself:

Quote:

Originally Posted by 400Eric

I may be pretty ticked (REALLY ticked actually) at this car right now but I couldn't do that. Not to a member of the family. I could send Benzer 1 to a new loving home but not to the junkyard. We brought our beautiful daughter home from the hospital in this car. At over 214,000 miles, this car gave me 136 MPH just for the cause of out top-ending a much younger Lexus GS just because it was something that needed to be done and was the right thing to do. This is the car that hooked me on Benzes and W-124s. That's why all of my subsequent Benzes are named after him. Nope, we have to fix him.

Ps2cho, pesuazo, the replacement of the OPV fuse solved all of the issues in my first post except for the ones I repeated in my third post.

Guys, I really need a quicker fix to this battery drain issue. Before I have to resort to GSXR's methods (which I really don't have time for right now), are there any known trouble areas/weak links where I should look first? Thanks again.
Regards, Eric