Started cold start stumble on 98 W210 - PeachParts Mercedes-Benz Forum

muleears · #1 02-06-2008, 07:13 AM

Last week my car started to stumble on cold starts. Seems to be missing two cylinders for about 20 sec. then one for another 20 sec. then OK. One day it started fine, the next day it had this problem. No error codes. Ambient temp. has been warmer than normal. First thing I thought of was a bad GP or two, but my glow indicator light still acts the same. I thought it would notify me of a bad plug. Could the injectors need cleaning? I have had this car for the last 20K mi. (all since august, lots of highway) No previous maint. records so I don't know when the plugs or injectors were done last. Any thoughts?

nate300d · #2 02-06-2008, 07:32 AM

First off I learned four months ago that a bad glow plug will not always trigger the glow plug and/or check engine light. My #3 tested bad. I replaced it and no problems.

From what you are describing and its inconsistency I question the fuel. Two years ago I had a fill from a fuel station that I used most of the time that was not 'bad', but made me question it. What happened to me was that at idle the engine would have a miss every few seconds whether hot or cold. As soon as you would raise the engine speed 300 RPM or more it went away. I have not returned to that station to purchased fuel and I have not had the issue ever since.

Just my experience.

nhdoc · #3 02-06-2008, 08:39 AM

Look for air bubbles in the clear fuel lines after you start it while it is stumbling. I'd bet that it is either a bad GP or a leak causing air. Like Nate said, GP faults do not always trigger a warning. Check them both and you will likely find the problem.

raMBow · #4 02-06-2008, 09:26 AM

Check for fuel leaks, especially under the shut off valve. And for significant air bubbles.

muleears · #5 02-06-2008, 09:40 AM

I have no fuel leaks. I will check for bubbles but I went through the air leak bit a few months ago and solved that problem then (thanks NhDoc) I hope. I replaced the SOV and O ring 10 days ago so that better not be leaking.

I will try to check the GP's tonite. I have a meter, I assume (yes I know) that there is a common plug where I can check the resistance of all plugs in the same place, like my 124? They should check out at <1 ohm? I'm leaning toward a bad pair of GP's, which scares the crap out of me

I can't afford to pull the head, I would just have to live with the stumble. Which plugs are reccomemded Beru or Bosch?

nhdoc · #6 02-06-2008, 09:53 AM

Quote:

Originally Posted by muleears

I have no fuel leaks. I will check for bubbles but I went through the air leak bit a few months ago and solved that problem then (thanks NhDoc) I hope. I replaced the SOV and O ring 10 days ago so that better not be leaking.

I will try to check the GP's tonite. I have a meter, I assume (yes I know) that there is a common plug where I can check the resistance of all plugs in the same place, like my 124? They should check out at <1 ohm? I'm leaning toward a bad pair of GP's, which scares the crap out of me

I can't afford to pull the head, I would just have to live with the stumble. Which plugs are reccomemded Beru or Bosch?

I have heard that both Beru and Bosch are supplying plugs to M-B, I believe the last ones I got from the dealerwere Beru. Check the GP's with your ohm meter, yeah, they ought to each measure between 0.6 and 1 ohm.

Good Luck.

Jadavis · #7 02-06-2008, 09:59 AM

Get into the habit of spraying the glow plugs with penetrating oil. PB Penetrating oil seems to get good marks from everyone I know.

http://www.pbblaster.com/store/moreinfo.cfm?Product_ID=1

Maybe after several weeks of this and some thermal cycling they will come out without a big problem. I have heard that a hot engine makes a huge difference also.

-Jim

muleears · #8 02-06-2008, 04:51 PM

I'm attempting to check my GP's. Is the attached pic the plug for the GP's? If so why are there only 5 pins? If not, where the heck is it??? This plug is located on the false firewall on the passenger side. Someone help before it gets dark

Jadavis · #9 02-06-2008, 05:14 PM

I don't know anything about the 606 engine, but this page shows how to do this on 603 and earlier engines. Might be the same on a 606.

http://www.dieselgiant.com/glowplugrepair.htm

-Jim

TMAllison · #10 02-06-2008, 05:20 PM

Wrong side. Look on the drivers side fender well next to the ABS.

Click buy parts tab above so you know what the relay looks like.

muleears · #11 02-06-2008, 05:20 PM

Thanks Ja, I have a 124 w/603 and unfortunately they aren't the same, wish they were and I wouldn't have to bother anyone

F18 · #12 02-06-2008, 05:33 PM

Muleears....the plug you want is attached to the PreGlow Relay on the driver's side...just above and behind the windshield washer bottle. It is retangular (about 4 1/2 inches long) and has a red "hot" wire to a screw post, and the large plug that has the leads to each of the glow plugs. You need to squeeze the large plug to release the Locks and wiggle it out. It will have all six of the contacts you can test with an Ohm meter.

Does anyone know which contacts in the plug go to which Glow Plugs?
It has a top and bottom row of 3 contacts each. Is it left to right and top to bottom starting with the front most glow plug? As I mentioned in a previous post my older MBs had numbers corresponding to the Glow plug on the Pre- heat Relay Plug. The W210s do not. ??

muleears · #13 02-06-2008, 07:56 PM

F18, found it and thanks for the help. Checked resistance and 5 were at .6 and one seemed to be infinite (all I got was a "1" all the way to the left of the readout) Anyway, it was the middle contact on the bottom row. So if we can figure out which plug that represents I'll know where to go. Thanks again for the help.

F18 · #14 02-06-2008, 09:25 PM

I am in the same boat......I would like to know which glow plug in the sequence it is.... No matter what, we still have to pull the manifold to get to any of them on our 606 engines. But I still would like to know before taking everything apart.

TMAllison · #15 02-06-2008, 09:38 PM

There are MB specific codes P1365, 66 & 67 which correspond to GP 1/2, 3/4 & 5/6. It may have been P1366,67 & 68. Sorry, can't remember exactly.

MBDOC posted on this 4-6 weeks ago; search his posts.