cb88

Having probelms here. ML320 stopped without warning. Starts, runs a few sewconds then stops. After several attempts, won't start again. If I try to put it into gear, it stops. Runs rough and knocking at low revs, but at 2,000 + it runs okay. No error codes. Tried changing AAM, EAM, ECU. Checked plugs, injectors, coils. Changed Crank angle sensor + camshaft sensor + MAF. Been on this problem for a month. I live in the country and need this vehicle to get to my farm. Starting to seriously affect my outlook on life. Any suggestions out there?

Maj. Dundee

Please UPDATE YOUR PROFILE in USER CP to include the year and where you live.

Maj. Dundee

Do you have a scanner or a code reader?

cb88

Yes an Autel OBDII. Doesn't show any codes. Goes better if I unplug the MAF, but still stops after a minute or two. If I unplug the MAF I get misfire codes on the scanner.

cb88

And yes, I've replaced the MAF with no effect.

Maj. Dundee

Of course you just ignored updating you profile.

cb88

I'm generally not comfortable with giving personal info to websites. But if it's important, sure, I'll update my profile. Hopefully that may help solve the problem with my vehicle.

Maj. Dundee

Let's no be paranoid about telling the forum the year of your ML and where you live.

cb88

Any useful suggestions out there? Anyone know about the AAC module and TAC issues on this vehicle?

E55Greasemonkey

Fuel pressure?

Maj. Dundee

cb88, the Autel OBDll is a mere code reader for the ECM only which will only reveal "P" codes.

You need a scanner type reader which will read codes in every module.

cb88

Thanks E55 Greasemonkey, but feul pressure seems good. Carefully checked fuel and ignition system elements, and started getting errors codes for misfires on cylinders 2,3 & 5. Switched around coils, plugs and injectors but no difference - still misfires in 2, 3 &5. Now I'm getting errors P2050 & P20CD and sometimes flashing CEL. Any suggestions/insights?

Maj. Dundee

You are getting misfire codes because you disconnected the MAF. Those codes must be cleared. Hopefully you did not damaged any spark plug leads.

Code P20CD is an A/C code. For the time being, forget this problem until you solve the eng. problem.

cb88

Thanks Maj. Dundee. Apologies, perhaps I wasn't clear. Replacement MAF isn't disconnected and when I swapped coils, I swapped the plug leads with them. AIso, I meticulously clear codes after each reading. These codes appear on a clean slate with each startup. Could this be a catalytic converter issue? The upstream O2 sensor on driver's side (RHS in Australia) doesn't appear very sooty or damaged. Current symptom: on the first start engine idles for around two minutes then inexplicably stops and throws misfire 2,3 & 5 codes. Subsequent starts it idles briefly before stopping and generates only two codes: P2050 & P 20CD. Any ideas?

Maj. Dundee

At what point did you get misfire codes? When you got the truck? After you did something? When?

If you had bad CATS you would also show P0172 P0174 rich codes.

cb88

The vehicle was mistakenly filled with diesel fuel. I drained the tank and it ran fine for about a week, then suddenly lost power over 1 km and stopped. That was when it showed the misfire codes.

Maj. Dundee

Why in the world didn't you make this known in your original post?

cb88

Great comment. A: No-one asked. The vehicle ran faultlessly in rugged country for ten days after.
Maj. I'm a little old for character building, I'm just here for problem solving - but I enjoy your forum. Any insights/suggestions to ease my dilemma would be gratefully appreciated.

khomer2

lol.
He's not character building, cb88. Maybe rough around the edges, but who isn't on these forums.
Respectfully, if you can't or don't disclose all the details, then be rest assured, you will voluntarily get lead in the wrong direction.
[just saying..]

Maj. Dundee

So you are saying that everyone that has misfire codes, someone on this forum should ask the poster if he put diesel fuel in the gas tank?

Well here are a few another questions, did you change the spark plugs? Did you do an oil and filter change? Did you change the injectors? Did you change the fuel pump?

cb88

Yes all of the above. Changed pump, filter, plugs and injectors.

Maj. Dundee

You opened this thread saying that you checked plugs, injectors, coils but you say nothing about the fuel pump.

Now you say you changed everything. Did you replace these components or did you just check them?

By the way, why would you replace the above sensors when they are electrical components and would not be affected by diesel fuel in your tank?

Since you live in Aust. there is no requirement that the CEL illuminate when there is a fault. Only in the USA is it required. Therefore you must check for codes in all modules with a scanner type code reader. Without codes, everything is guesswork.

cb88

I replaced the components. Why? Because I kept getting the same three misfire codes on cylinders 2, 3 & 5 indicating a consistent problem that didn't disappear. I did get the CEL light illuminating. After several weeks trying to locate the source of the problem, I removed the O2 sensors: LHS were wet with residue. With the O2 sensors gone, the vehicle suddenly idled again. I figured it could be a catalytic converter, so I took the sucker out and opened it up and to my surprise the chamber was empty - the cat had been removed some time ago. (The RHS cat appears to be intact.) I only took possession of this vehicle two months ago. While it has proven to be a pandora's box, it has also been an intensive learning experience. I am wondering if, with an empty catalytic converter, the O2 sensors were not reading faults. What would be the effect on the ECU if these O2 sensors were fouled with unburned diesel fuel? Would this cause rough idling, loud ignition knocking and prevent the car from running? And could it possibly generate consistent misfire codes in cylinders 2, 3 &5? As I stated earlier, with the affected O2 sensors out of the vehicle, it idles as of old. Any suggestions as to what to do next? What are the lingering effects of diesel fuel running through the system? Many thanks in advance if you have any insights.

RollTideW163

I'm sorry but "No one asked" LOL

Putting in diesel and running it can conceivably damage the pistons if you have a vehicle such as I don't know, say a gay landrover - but I think a Benz engine could survive if you aren't constantly running. The answer to your question about the knocking and running badly are yes. The diesel is not combusting. I'm not sure that its the O2 sensor that is fouled per se, but in general this is obviously what caused all this. I'm super confused as how you threw all these parts at the car prior to getting a code and getting all the diesel out. Draining the tank wasn't enough it was probably all in your lines.