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Rack travel at idle with 6mm elements - Printable Version

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Rack travel at idle with 6mm elements - baldur - 05-08-2015

I'm wondering if anyone knows what is typical for rack travel at idle on an OM606. I'm finding the rack needs to travel quite a bit before any fuel starts to come out of the injectors and I'm wondering if it's normal.

RE: Rack travel at idle with 6mm elements - barrote - 05-09-2015

about 13mm

RE: Rack travel at idle with 6mm elements - seanyt - 05-09-2015

is 13mm correct. Isnt the edc pump travel only about 18/19mm max
Leaving you only 5-6mm travel to control fuel.

From watching Dieselmekens edc video that he adjusts the racks sensor at idle. 
He says that idle value is at 6.7mm, he then adjusts the rack sensor and element points so rack travel at idle is 5.7mm.

RE: Rack travel at idle with 6mm elements - baldur - 05-09-2015

(05-09-2015, 12:52 PM)seanyt is 13mm correct. Isnt the edc pump travel only about 18/19mm max
Leaving you only 5-6mm travel to control fuel.

From watching Dieselmekens edc video that he adjusts the racks sensor at idle. 
He says that idle value is at 6.7mm, he then adjusts the rack sensor and element points so rack travel at idle is 5.7mm.

Sounds about right then. I'm seeing about a third of the maximum possible travel at idle, going by the feedback from the rack position sensor.

RE: Rack travel at idle with 6mm elements - seanyt - 05-09-2015

In the video idle is set at 1.97v
so that's spot on then for a 5v range.

RE: Rack travel at idle with 6mm elements - baldur - 05-09-2015

Now the question is, how much travel is typical for a mechanical governor pump at idle and how much maximum travel the mechanical governor can give. I'm trying to figure out how much range I need to give the elements from idle to full load to get the full 90CC they're supposedly capable of.

RE: Rack travel at idle with 6mm elements - seanyt - 05-09-2015

The mechanical pump is 21mm travel and to the best of my knowledge the edc gives 18/19mm travel max. But the stock edc ecu shuts down if the rack goes beyond a certain point.
Not sure what the stock pump will deliver cc wise and a what rack travel. So you can scale it correctly.

RE: Rack travel at idle with 6mm elements - baldur - 05-10-2015

I am not using the stock ECU so I'm not bound by its design.
I'm sure it's simple to get more travel out of this EDC pump by altering the end stops and possibly just moving the forks on the rack so that idle happens at maybe a quarter of the travel rather than a third.
Right now I'm just wondering what kind of fuel flow I can expect to get without altering the pump. I'd ask Dieselmeken but he's on vacation AFAIK.

RE: Rack travel at idle with 6mm elements - seanyt - 05-10-2015

Haha im totally aware your not using the stock ecu  Smile
I have an edc 8mm pump here but not in a position to go opening it to check the stroke length. 
If i swap it in, in the next while ill open the stock pump and check. 

Surely a diesel service company has a calibration spec or certificate that will show what cc it flows at certain stroke lengths
Or at very least bosch should have a set standard for this pump to give you a ball park figure.

My 8mm dieselmeken edc pump is marked 170 Im guessing thats maximum flow with the forks moved and rack at full travel.

RE: Rack travel at idle with 6mm elements - baldur - 05-16-2015

For the record, the travel of an EDC pump is 19mm. It would be interesting to know at what kind of rack position a mechanical pump idles at.

RE: Rack travel at idle with 6mm elements - seanyt - 05-16-2015

I presume the same they just have a small amount of extra travel.
Your probably one of few who can use the full edc rack travel.
Everyone is using stock edc ecu and it limits rack travel based on rack sensor.

your ecu at least will enable more fuelling.
even thought my 8mm pump is marked 170cc i believe 140-150 of that is usable when using the stock ecu.
Your ecu will give the full beans Smile
is it ready yet..........
is it ready yet.........

RE: Rack travel at idle with 6mm elements - baldur - 05-16-2015

Yes, I'd say the ECU is ready. The OM606 swapped P38 Range Rover survived its maiden voyage with WOT fuel set to the maximum the pump can deal and the HY35 turbo at wastegate pressure but we don't know how much boost that was because the owner forgot to tap the intake manifold for a place to connect the manifold pressure sensor.
Power and drivability are decent, programmed the Compushift to shift gears at 5300RPM, we'll need to do more testing to find how high it really needs to rev to make the most of the available power. It didn't feel like it was starting to slow down at 5000.
The idle hunts just a little bit, +- 50RPM from the 700RPM setpoint because of stiction in the rack, it doesn't respond immediately to small changes in current so the PID control can't lock the idle fuelling perfectly. I might be able to get it smoother with further tuning of the control loop or doing some changes to the algorithm. The rack control works well and the temperature compensated position feedback is spot on.
We're having some cold starting problems, probably due to a leak somewhere letting air into the fuel lines, the engine will catch and run but then stall and take maybe 10-15 seconds of cranking before it runs again.
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RE: Rack travel at idle with 6mm elements - seanyt - 05-17-2015

Great work, there are some very talented om606 owners on this forum. That really contribute and go out of there way.
looks like a small form factor aswell.
interested to see it in the future. 

RE: Rack travel at idle with 6mm elements - Thebigroyboyski - 05-20-2015

The standard rack setting for my pump number is set to 6.5mm at idle and 13.95mm at 1000rpm. Excess fuel is 20-32mm.
That on a 0 400 076 962 OM603 Turbo pump.

That all taken from the Bosch test plan.

Edit; Forgot to say thats on a completely standard pump with 5.5mm elements and no mods.

RE: Rack travel at idle with 6mm elements - olefejer - 05-20-2015

Hi Baldur   you wrote
The idle hunts just a little bit, +- 50RPM from the 700RPM setpoint because of stiction in the rack, it doesn't respond immediately to small changes in current so the PID control can't lock the idle fuelling perfectly. 


You should really try to lower the Frequency on the PWM signal, Lower Freq would have the rack move back and forward a tiny bit all the time, then you do not have it sticking anymore, maby as low as 30 - 70 HZ

RE: Rack travel at idle with 6mm elements - baldur - 05-20-2015

(05-20-2015, 11:03 AM)olefejer You should really try to lower the Frequency on the PWM signal, Lower Freq would have the rack move back and forward a tiny bit all the time, then you do not have it sticking anymore, maby as low as 30 - 70 HZ

Yes that thought had occurred to me, inducing vibration to fight the stiction. I just haven't spent much development time with a running engine. I saw the stiction in the lab but I had hoped it would go away when the pump was rotating, evidently it didn't.