[allis chalmers]

Well hello folks, I guess the title sums up my mood right now.

The subject is my 2000 ML320, 31k miles, bought it new.

Yesterday, without warning, it died about a mile from the house. It misfired for a few seconds before it died, and then it was/still is dead. I towed it home with my trusty 1951 Farmall Super A tractor.

Here is what I have done so far/some facts:

1/2 tank of fuel, with 50psi of fuel pressure at the rail, leaks down to around 42psi after 30 minutes.

Stored codes show P0300, and also individual misfire codes for every cyl except one(I don't remember right now). Freeze frame data shows rpm of P0300 to be 545rpm and open loop.

Checked all pertinant fuses.

I replaced the crank position sensor about an hour ago with no change(bought at local dealer).

The cluster does not showan error code in the odometer display, and the red led lights up under the low range switch.

The only thing I can think of is that the CPS has to be reinitialized, I could probably borrow the tool to do that or use my MT2500, but stup!d me can't find the round diagnostic port under the hood.


Any thoughts are most welcome, I really need to get it fixed asap because my wife uses it as her daily driver now.

Getting it towed to a dealer/shop is almost impossible, we live way out in the boonies. I don;t relish the thought of the bill or possible damage done by the tow company.


Thanks for any advice you folks can give.... talk about a head scratcher......

 

[43sqd]

There is no round diagnostic port on ML's. The only diagnostic port is above the brake pedal, which I guess you already know about.

 

[allis chalmers]

Well, now I understand. I guess I need to figure out what personailty key to use and also find a obdII interface for my MT2500 if it turns out I have to reinitialize the crank position sensor.

One more tidbit, when it cranks over it doesn't sound very even. It sounds like a car with low compression on a cylinder or two. Could the timing chain have jumped while it was running. I sure hope not......with only 31k miles and Mobil 1 since the first oil change. :crybaby2:

 

[Check Codes]

Well, at least you didn't have to tow it home with an A-C Harvester.

There is also a cam position sensor on the front of the engine (passenger side) which can fail with similar results to what you're describing. I have also heard of the wire to the CPS being routed incorrectly so that it chafes and then shorts out, so check that as well.

IIRC the cam sensor is cheaper and even easier to change than the crank sensor, given your description of trying to get it in that would probably be my next shot. You have probably already surmised that the fuel situation is fine.

BTW, try disconnecting the battery for a few minutes, that will reset a couple of things to default. Maybe try that first, then see before going after the cam sensor?

 

[43sqd]

The first thing you should do is recheck the installation of the CKP sensor, make sure it is properly connected.

If it is you should check for spark with a spark tester.

Since you have an MT2500, for now you do not need a MB personality key. Simply use Generic OBDII with key 2 or 2A. After you are hooked up to the DLC (Data Link Conn.), monitor RPM and with a sustained crank of 10-15 secs. see that a reading appears. If it doesn't then there is something wrong with the CKP sensor or the wiring to it.

 

[allis chalmers]

The first thing you should do is recheck the installation of the CKP sensor, make sure it is properly connected.

If it is you should check for spark with a spark tester.

Since you have an MT2500, for now you do not need a MB personality key. Simply use Generic OBDII with key 2 or 2A. After you are hooked up to the DLC (Data Link Conn.), monitor RPM and with a sustained crank of 10-15 secs. see that a reading appears. If it doesn't then there is something wrong with the CKP sensor or the wiring to it.

The MT2500 has been a red herring for me, I bought it used and I only got the round 30?pin connector, the x/11 connector, one key s-22, and the cartridge.

I did hook up my OTC PalmScan, and it does show rpm while cranking, and the fuel pump also energizes while cranking. The MAF shows movement in g/sec while cranking.

The funny thing is that with the key on engine of, the ignition timing is -54 btdc, while cranking it goes to -14 btdc.

I will check for spark in the morning, and guesses as to why I would lose ignition?

Also, I can't clear the DTC's (P0300, and every individual cylinder except #1)for the misfire, they are " permanent".

Thanks for your help.

 

[allis chalmers]

Well, at least you didn't have to tow it home with an A-C Harvester.

There is also a cam position sensor on the front of the engine (passenger side) which can fail with similar results to what you're describing. I have also heard of the wire to the CPS being routed incorrectly so that it chafes and then shorts out, so check that as well.

IIRC the cam sensor is cheaper and even easier to change than the crank sensor, given your description of trying to get it in that would probably be my next shot. You have probably already surmised that the fuel situation is fine.

BTW, try disconnecting the battery for a few minutes, that will reset a couple of things to default. Maybe try that first, then see before going after the cam sensor?

I sure am glad I had just serviced the Farmall and it had a fresh battery and a full tank. Most of the cars that went by honked and gave us a big thumbs up.

I might try the cam sensor, first I'm going to check for spark. Would a faulty cam sensor lead to a no spark condition?

 

[43sqd]

The MT2500 has been a red herring for me, I bought it used and I only got the round 30?pin connector, the x/11 connector, one key s-22, and the cartridge.

I did hook up my OTC PalmScan, and it does show rpm while cranking, and the fuel pump also energizes while cranking. The MAF shows movement in g/sec while cranking.

The funny thing is that with the key on engine of, the ignition timing is -54 btdc, while cranking it goes to -14 btdc.

I will check for spark in the morning, and guesses as to why I would lose ignition?

Also, I can't clear the DTC's (P0300, and every individual cylinder except #1)for the misfire, they are " permanent".

Thanks for your help.

Go to e-bay and search for Mercedes DL16 adapter. With the adapter you will need personality keys S4, S17 and S20 which will cover everything. You can also check for the aforementioned keys, but the prices on ebay are too high. Go to Snap-On.com and search for personality keys and they will ship them to your home. They are about $18-20 each.