Where do I start? Numerous problems with my 606 - PeachParts Mercedes-Benz Forum

muleears · #1 11-24-2008, 05:49 PM

I still hadn't resolved the poor performance/hesitation problem from a few weeks ago and now I have more problems.

It still throws the P0100(EGR) code consistently. It had been throwing the P0243(wastegate) and P0400(maf) codes previously. This morning I reset the codes and only the P0100 has returned.

Symptoms are this: Runs best from a cold start (remember I still have the low power/hesitation problem) will accelerate up to 60 in 1/2 mi. Once shut off and restarted before a complete (several hour) cool down, the performance is immediately markedly worse. Misfires badly on apparently different cylinders, surges even worse than before, won't go above 35mph and gets there very slowly. But idle is ok. Revs in park ok but stumbles as RPMS fall past 1000

I have:
replaced the shutoff valve
installed a new MAF
swapped vacuum transducers (turbo+EGR)
Checked for loose/deteriorated vacuum lines
run the car with the filters off the transducers (to see if they were plugged)
Changed all filters (except tank screen)
More that I can't remember at the moment

What else can I do? I need the car to get to work as it is now I don't trust it. Today I drove in to work and let it cool all day and it ran well enough to get me home (40mi.). I then shut it off and started it again and it ran like crap. Still only the P0100 code. Any help is greatly appreciated.

KarTek · #2 11-24-2008, 06:02 PM

I really feel for you man... The only thing I can think of is wiring harness integrity or maybe a bad ECU. Even though that's rare, I don't think it's unheard of.

muleears · #3 11-24-2008, 06:25 PM

I even thought, maybe I put gas in by accident

But it wouldn't run at all on that, besides last time I filled it, it was empty and I filled it full. Which brings up another issue, could a bad tank of diesel contribute to this? It was bad before but now it has the hot restart problem. That problem seems to be consistent though. If it is started cold it will run passably until shut down. Even if its just a few minutes, when restarted it runs horribly.

KarTek · #4 11-24-2008, 06:42 PM

It's just strange because the ECU only effects performance in a couple of ways:

1. Fuel rack position
2. EGR on/off
3. Boost on/off

It's hard to say which part of this is causing the problems...

husk · #5 11-24-2008, 07:15 PM

I assume you checked the boost pressure line from the boost controller?

Chris W. · #6 11-24-2008, 07:39 PM

I know it's a very long shot, but you might consider replacing the lift pump. Not that expensive, very easy job if you have the intake manifold off (may be doable from underneath without taking off the manifold but I didn't think of it at the time).

Replacing mine solved a lot of weird run-ability problems I was having.

Rgds,
Chris W.
'95 E300D

TMAllison · #7 11-24-2008, 07:56 PM

Cal - I know this has gone on and on and may have been asked, but is it possible you've got the vacuum lines from the turbo boost and EGR swaped?

muleears · #8 11-24-2008, 08:04 PM

Husk, read your other thread about that hose and have checked it. its ok.
Chris, hadn't thought about the lift pump, why would a hot restart cause it to really screw up?

Terry, I don't think they are long enough to mix up, unless I'm thinking of the wrong ones. One comes from the boost controller and the other from the vacuum transducer correct?

husk · #9 11-24-2008, 09:17 PM

I am 90% sure that the problem is with your boost control module...are you getting any boost pressure? Connect a gauge and check this first.

barry123400 · #10 11-24-2008, 10:47 PM

Quote:

Originally Posted by muleears

Husk, read your other thread about that hose and have checked it. its ok.
Chris, hadn't thought about the lift pump, why would a hot restart cause it to really screw up?

Terry, I don't think they are long enough to mix up, unless I'm thinking of the wrong ones. One comes from the boost controller and the other from the vacuum transducer correct?

I am not myself saying or suggesting it is the lift pump. As an explanation of why more pronounced when warm though. The fuel would have warmed up perhaps thinning or losing viscosity further impacting on leaky valves in the lift pump is a possibility.

Further lowering available fuel pressure. Because of the missfire you quote and slow acceleration I might want to do a fuel pressure check just in case though. You could easily be starving for fuel.

husk · #11 11-24-2008, 09:30 PM

On second thought it could also be that the replacement MAF that you purchased is also bad. IF possible I would return your "new" MAF and get another replacement to see if this fixes your problem. You did change your airfliter when chaging the MAF right?

notfarnow · #12 11-25-2008, 08:28 AM

Quote:

Originally Posted by muleears

Changed all filters (except tank screen)

Hmm

I'm no 606 expert, but your symptoms almost sound like high vacuum in the fuel lines, from a pinched line or plugged filter.

I would be very tempted to hook up a vacuum gauge to see what readings you get. With a new diesel filter, I NEVER get above ~8-9 inHg

KarTek · #13 11-25-2008, 08:57 AM

OK, this is what I'd do if it was me. You may have done some of these already but I'll just mention then in order of how I would do it. We'll tackle one area at a time.

1. If you don't already have one, get a MityVac kit. About $50, has a bunch of adapters and stuff you need.

2. Check your turbo boost control system by doing the following: With the engine running, connect the MityVac to the vacuum line leading into the boost modulator and observe a vacuum. Should be good and strong all the time the car's running. reconnect the line into the modulator and pull the one off the wastegate and check for vacuum here. Again, should be strong.

Now, you can shut the car off and then, pull both lines off the modulator and use the little yellow (or whatever color it is) 2 sided connector and join the inlet to the outlet. This will supply full vacuum to the wastegate all the time, regardless of computer intervention. Take the car for a drive and see if its performance is improved. If so, we can work from there, if not, we'll check other things. Don't accelerate the car too hard with the modulator bypassed because it will overboost. Just get on it hard enough to a point where it would normally generate boost and you would feel it.

muleears · #14 11-25-2008, 10:15 AM

Thanks Evan. I will try to do the first part of that tonite. I have a mighty vac already.

Boost modulator is the same as the boost controller mentioned previously? Small box on drivers false firewall? One vac. and one elec. connection? Or is it what I call the transducer(?) mounted on the top of the fenderwell, three vac. lines, drivers side, next to the ABS?

Not sure where the line to the wastegate is, I assume (yes, I know) it is one of the lines off of the transducer(?) mounted low behind the pass. headlight? If so which one, center, edge or bottom. I know one goes to the filter but I forget which one.

Hate to appear a dunce but I'm far from an expert on this car.

Thank you very much for the advice.

husk · #15 11-25-2008, 10:47 AM

P0100 is the MAF, check this first!!