GP light, valves adjusted, still no luck, engine misses - PeachParts Mercedes-Benz Forum

siral3x · #1 10-07-2007, 12:34 PM

I have done the valve adj yesterday night, changed fuel filters and I still have the same problem:engine is missing at idle for a couple of minutes and smokes;

-no glow plug light: everything checks OK but the light just won't turn on(checked fuse, replaced all GP last week, voltage is ok at all 5 pins and all 5 gp, relay clicks ON ,everything looks fine, still no light, don't know what else to do);

-adjusted valves and it seems to runs smoother after FIRST 8-10 minutes at idle, the first 8 smokes and sputters and misses;

-I checked the timing chain and it looks nice and tight +timing is not off;
-I know for sure compression is fine bc I can start the car without glow and it runs the same for the first 10 min, then BAM eveything is fine.
-air filter is ok, EGR valve looks good, NO fuel leaks....;

I'm starting to regret I bought this 85 300T D. I mean it's just stupid that I have to wait 10 min every morning till the engine stops missing to drive the damn thing down the road. I tried almost anythign I could think of and it still sputters smoke and misses at idle. In Michigan we're still in the 80s now BUT what am I gonna do when it goes to 10-20 this winter??

junqueyardjim · #2 10-07-2007, 04:34 PM

You think you know the compression, but you don't know anything until you check it. If you have one or two cylinders that are quite low while the three are in the high normal range of 400 it will start on a warm day. But when you start it on a cool morning with the glow plugs, as soon as the glow plugs cool off it will run very weak, (a miss in effect) until the engine warms up. Better do the test and then you will know for sure.

barry123400 · #3 10-07-2007, 07:39 PM

You did check each individual glow plug for continuity with an ohmeter? Just the voltage reaching each plug means nothing really. Also if one plug is bad sometimes the dash indicator for the glow circuit will stay extingished . I believe I have read but not experienced this myself.
I do not know if your car would have the long afterglow plugs. Others will comment. Or you could monitor the plug voltage to find out if they stay on after the initial period yourself.
Once you are positive the glow plugs are working. Then I would try loosening each fuel line at the injectors one at a time to see if it is a particular cylinder or an overall condition like too much air in the fuel supply initially. No reason yet to get really concerned. Another thing with this type of complaint is to remove the return line from the injection pump just to make sure there is enough fuel and pressure in the pump to have some excess coming out of the pump.
Or if you happen to own a diesel compresion checker you might want to get that out of the way first. If not it can wait until a few things are checked out.
Sorry went back and see you have changed the glow plugs out so start at the next item.

junqueyardjim · #4 10-07-2007, 07:56 PM

That could be caused by a burned out bulb and will necessitate pulling the instrument part of the dash. Not a bad job, but in the midst of others, it is a pain. But you can well run the car without the glow plug light with no problems. Just watch your clock or count off 15/20 seconds before you crank it up.

toomany MBZ · #5 10-08-2007, 05:15 AM

If you have the chance, swap out your relay, see if that helps. Also, if you get the chance, while the engine is stumbling, crack open the fuel line at the injectors, one at a time to determine if a certain cylinder is not firing. May help to pin point your problem.

siral3x · #6 10-08-2007, 08:55 AM

I let the car glow for 25sec yesterday morning, it fired right up and it did not miss/ stumble/smoke almost at all.
I just changed the pre filter+ main fuel filter, and did a diesel purge too.
I found a lot of gunky **** in the main filter and it had 04/05/2004 date written on it. I can't really belive the car ran with that one plus it was way overdue.
The old Benz seems to like that diesel purge stuff, I guess I'll have to do a cold start on Sunday and see the results bc the temp is supposed to go from 80 to 30

funola · #7 10-08-2007, 09:46 AM

The cluster glow plug light is not on the same circuit as the glow plugs. It does not tell all. If it's not lit, it could be the bulb, the controller, or wiring/connection in between.

Brian Carlton · #8 10-08-2007, 09:57 AM

Quote:

Originally Posted by siral3x

I let the car glow for 25sec yesterday morning, it fired right up and it did not miss/ stumble/smoke almost at all.
I just changed the pre filter+ main fuel filter, and did a diesel purge too.
I found a lot of gunky **** in the main filter and it had 04/05/2004 date written on it. I can't really belive the car ran with that one plus it was way overdue.
The old Benz seems to like that diesel purge stuff, I guess I'll have to do a cold start on Sunday and see the results bc the temp is supposed to go from 80 to 30

This result rules out the glow plugs. The greater heat from the plug over a longer time gives better combustion when you go to start it.

Unfortunately, this does point to the fact that one cylinder is probably low on compression..........or the prechamber is not in good condition...........or one injector is not atomizing fuel properly.

It would be advantageous to find the culprit cylinder by cracking each injector line in sequence. Do this when you have the problem. The engine will get noticeably rougher and might even stall on when you crack four of them. The fifth will have no effect........the stumbling will remain identical to before you crack it. That's your culprit cylinder and then we can proceed forward from that point.

siral3x · #9 10-08-2007, 04:42 PM

Quote:

Originally Posted by Brian Carlton

This result rules out the glow plugs. The greater heat from the plug over a longer time gives better combustion when you go to start it.

Unfortunately, this does point to the fact that one cylinder is probably low on compression..........or the prechamber is not in good condition...........or one injector is not atomizing fuel properly.

It would be advantageous to find the culprit cylinder by cracking each injector line in sequence. Do this when you have the problem. The engine will get noticeably rougher and might even stall on when you crack four of them. The fifth will have no effect........the stumbling will remain identical to before you crack it. That's your culprit cylinder and then we can proceed forward from that point.

Yeah this is going to be my next step. I really miss my dads C 220 CDI that has no glow plugs and starts like butter + the 6 speed manual is bad ass, gets you 50mpg+.

Not to mention my 1.4 TDCI Ford that gets 60mpg+

siral3x · #10 10-29-2007, 09:32 AM

I started my Benz yesterday morning in the low 30s, and it seemed that I couldn't glow more then 5 sec?? the relay didn't click on(the light is still OFF, won't turn back on).
Well it started up with no dificulty and was blowing some white/graysh smoke and I know it's partial unburnt diesel. FOr the first 5 sec it ran with no missing, then the engine started missing again for 5 min, then smoke went away and missing also.
I'm starting to think that my GP relay is going bad. I though the GPs glow 40 sec or so, but now that I recall I had voltage to the GP only for 5-6sec when I initialy tested them.

siral3x · #11 10-29-2007, 09:36 AM

Also my uncle told me that the diesel fuel is 1 year old in the tank

, and I haven't been driving it at all almost since the Benz it's having issues.

siral3x · #12 10-29-2007, 09:39 AM

What is the procedure to test the GP relay itself?? I followed dieselgiant method by testing the pins for voltage, and there is 11.5v for 4-5 sec on each pin + at the glow plugs the voltage stays on for 4-5 sec also, no way near to 40 sec???

funola · #13 10-29-2007, 10:28 AM

An easy way to test the glow plug relay is simply clip a light bulb across the glow plugs and watch. 4-5 seconds is not long enough if it is indeed so short. Search for posts from me where I talk about ways to test glow plugs without having to remove them.

Quote:

Originally Posted by siral3x

What is the procedure to test the GP relay itself?? I followed dieselgiant method by testing the pins for voltage, and there is 11.5v for 4-5 sec on each pin + at the glow plugs the voltage stays on for 4-5 sec also, no way near to 40 sec???

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