OM603.960 Low power, high consumption - Page 2 - PeachParts Mercedes-Benz Forum

FrodeS · #16 11-01-2010, 02:44 PM

BTW, the car is running on normal diesel. I tried bio diesel made from fish waste some years ago, but it made the car a lot slower.

jt20 · #17 11-01-2010, 02:45 PM

Is it possible that you are not getting fuel enrichment with boost?

This would explain the consumption. And the high RPM boost drop.

It may sound backwards that less fuel means higher consumption, but spinning the turbo takes energy.

Perhaps adjusting/ testing the ALDA might be your next step?

FrodeS · #18 11-01-2010, 02:50 PM

Quote:

Originally Posted by jt20

Is it possible that you are not getting fuel enrichment with boost?
This would explain the consumption. And the high RPM boost drop.
It may sound backwards that less fuel means higher consumption, but spinning the turbo takes energy.

Perhaps adjusting/ testing the ALDA might be your next step?

Almost everything is possible :-)
Would this explain the 15-20% increase in consumption I experience?

I've read about adjusting the alda, but how can I test it?

It seems it takes too long to spin up the turbo, but when it spins, power at the low end seems to be OK (I think)

jt20 · #19 11-01-2010, 03:23 PM

post #15 makes sense, but I cannot comment further with experience.

I also cannot comment on the accuracy of the consumption numbers.

To adjust the ALDA, find the square disk on top the injection pump.

You will either see a cylinder with a black cap (picture) or a locknut around a flathead screw. Turn this screw out or Counter-clockwise, but gently.

You will have to make adjustments by trial and error, just do not force the screw beyond its stopping point. For reference, 1/4 should be a little noticeable, and 2 turns is about the most adjustment you will get.

Keep track of your adjustments.

I hope it at least provides you with some more info regarding your problem.

babymog · #20 11-01-2010, 04:08 PM

A leaking / open wastegate would affect the boost at low RPM more than high RPM. The wastegate does not seem to be the problem according to the boost numbers you posted earlier.

jonbobshinigin · #21 11-01-2010, 05:50 PM

Has the Overboost protection valve been bypassed already?

scottmcphee · #22 11-01-2010, 06:02 PM

Taking the ALDA off completely, first, is easier diagnostic step than trying to adjust it (possibly breaking it).

I don't get how less power and more consumption go together unless there is new resistance in the equation somewhere - like severe wheel alignment issue. (Rear toe-in? Always driving up an constant incline both ways to school in a snow storm...?)

Barring that it sounds like fuel quality (lower energy), or a mucked up IP - squirting at the wrong time. Does it knock? Blow grey smoke?

You say refreshed timing chain... did they get the timing right?

FrodeS · #23 11-01-2010, 06:06 PM

Quote:

Originally Posted by jonbobshinigin

Has the Overboost protection valve been bypassed already?

I have tried, but it made no difference. Bypassed it bye connecting the line from the intake manifold directly to the alda.

I know how to adjust the alda, either by the screw on the top, or by taking it out and applying chims underneath, but how can it be tested, and will adjusting it influence anything else than amount of diesel before the turbo spins up?

FrodeS · #24 11-01-2010, 06:15 PM

Quote:

Originally Posted by scottmcphee

Taking the ALDA off completely, first, is easier diagnostic step than trying to adjust it (possibly breaking it).

I don't get how less power and more consumption go together unless there is new resistance in the equation somewhere - like severe wheel alignment issue. (Rear toe-in? Always driving up an constant incline both ways to school in a snow storm...?)

Barring that it sounds like fuel quality (lower energy), or a mucked up IP - squirting at the wrong time. Does it knock? Blow grey smoke?

You say refreshed timing chain... did they get the timing right?

I follow your thoughts, but can assure the wheel alignment is correct, and there is nothing holding the car back.

I had a garage change the chain. I usually do most work my self, but not this one. They did adjust it, and I can only trust they did it correctly.
I must assure the timing is correct, but is that a guarantee the IP is delivering fuel at the correct point? If fuel delivery is a little to late, I suppose it would influence power at the higher RPMs the most, correct? Can this be tested in any way?

It does not knock, rather the other way round, people say it knocks very little. The sound is as smooth as only a MB inline six cylinder can be.

jt20 · #25 11-01-2010, 06:24 PM

Quote:

Originally Posted by FrodeS

I know how to adjust the alda, either by the screw on the top, or by taking it out and applying chims underneath, but how can it be tested, and will adjusting it influence anything else than amount of diesel before the turbo spins up?

the easiest way to test it is by doing the incremental method, or by swapping it out.... maybe applying some pressure to it to see if it holds.

Yes, the adjustment only adds more fuel at an earlier response to boost.

currently, removing it would be just as good of a test. Its just not something I would recommend to someone without more knowledge of their background.

Regardless. There is a large amount of speculation going on, with little action. Things will only get more confusing until some further data / testing is supplied.

W124 E300D · #26 11-01-2010, 06:30 PM

If you lower compression but leave everything else the same...

1/ Brake Thermal Efficiency rises against Brake Horse Power.

2/ Fuel consumption rises against Brake Horse Power

3/ Exhaust gas temperature (energy) drops against Brake Horse Power

4/ Smoke density drops against Brake Horse Power.

Basically dropping the compression makes for a cleaner burning, less NOx producing, more thermally efficient, less fuel efficient, less powerful engine.

The turbo diesels are slightly lower CR than the non turbo, to allow for the turbo boost.

Basically from all the signs matey's turbo is shot. Either the unit itself or the plumbing, but he is running lower than spec compression.

Compression test won't catch it.

Take the car to a turbo specialist.

FrodeS · #27 11-01-2010, 06:38 PM

Quote:

Originally Posted by jt20

currently, removing it would be just as good of a test. Its just not something I would recommend to someone without more knowledge of their background.

Regardless. There is a large amount of speculation going on, with little action. Things will only get more confusing until some further data / testing is supplied.

Can I (test)run the car without the alda?

I know little is done. I will test "cleaning" the WG as I was advised first, only problem is finding time to do everything. Winter is knocking on the door, and I am in the middle of digging drainage around the house. I've spent all summer digging out half a metre of soil from the basement, and all winter and next summer will probably be spent converting the basement into usable rooms.

I am hoping someone will recognize the symptoms of my car, and maybe have some experience with the same problems. After all, this cars do grow on trees, and the mileage on mine isn't extraordinary high.
There must be a reason for the drop in boost pressure. As far as I can see, this must be because of :

1. Turbo not able to deliver enough air even if there is enough exhaust (turbo worn out?).
2. Too little diesel --> too little exhaust --> too little boost.
3. Diesel delivered too late, making the exhaust pressure drop, and therefor it is not enough pressure into the turbo.

I think this is the main reasons that can influence the boost pressure. Each reason may have different causes.

FrodeS · #28 11-01-2010, 06:41 PM

Quote:

Originally Posted by W124 E300D

Basically from all the signs matey's turbo is shot. Either the unit itself or the plumbing, but he is running lower than spec compression.

Compression test won't catch it.

So what you say is the turbo is worn out?
Or the compression in the engine is too low?

Or both?

BTW, all the OM601, 602 and 603, NA and turbo charged all have 1:22 compression ratio, 87 / 84 millimeter bore / stroke . At least the euro spec.

jt20 · #29 11-01-2010, 06:47 PM

Quote:

Originally Posted by FrodeS

Can I (test)run the car without the alda?

There must be a reason for the drop in boost pressure. As far as I can see, this must be because of :

1. Turbo not able to deliver enough air even if there is enough exhaust (turbo worn out?).
2. Too little diesel --> too little exhaust --> too little boost.
3. Diesel delivered too late, making the exhaust pressure drop, and therefor it is not enough pressure into the turbo.

I think this is the main reasons that can influence the boost pressure. Each reason may have different causes.

you can run the car without the alda, but if you remove it, you must be careful not to run for extended periods of black smoke (ie.. heavy acceleration). You must be gentle with the pedal and know the limits.

I suggested the screw tweaking since it is usually easier to accomplish... for both time and labor
....you will not break it if you are gentle.

2. this possibility can be mostly removed by 'testing' the ALDA.

3. Early injection timing causes turbo lag / less exhaust pressure.

FrodeS · #30 11-01-2010, 06:51 PM

Quote:

Originally Posted by jt20

3. Early injection timing causes turbo lag / less exhaust pressure.

It takes a long time to spin my turbo from standstill. It goes slowly up to 0,5 bar, from there it spins rapidly up to 0,85 wich is correct.

Early injection would also cause knocking, right? Mine does not knock. How about late injection? Can the pump for some reason deliver the fuel too late, even if the timing seems to be correct?