Omega Owners Forum
Omega Help Area => Omega Electrical and Audio Help => Topic started by: korte22 on 19 October 2025, 17:31:54
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Hello.
I have 2000 Omega B2 with BMW's M51 diesel engine. This car was originally automatic but that transmission broke. I swapped manual tranmission but now car has high idle and rough start.
Before transswap it had normal idle and great starts even in cold weather. I did solder two thick wires from autotrans loom together so now it starts. I have read this forum because someone had similar issues after manual swapping but none of these have helped me. https://www.omegaowners.com/forum/index.php?topic=97236.msg1218947#msg1218947 That pin 24 they talked about here had no effect after grounding it. There was talk about some other pins but I have no idea what those are. Mechanically car works great but that idle and rough start is terrible.
Engine codes with "My Naff Code Reader" gave wrong engine speed and I changed flywheel sensor to new high quality one. This had no effect either and it still gives that code.
Does anyone know that wires is should join together or what should i do?
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If you can read a wiring diagram, the diagrams in Haynes cover the 2.5td.
Randomly joining wires because the Internet tells you too is unlikely to end well.
It's possible that the engine ecu needs reprogramming to tell it that it's a manual now. The idle fueling is probably set to alow for the extra drag of the torque converter and gearbox pump. Should be a box tick with Tech 2.
And use the diagrams to cross check what you've altered :y
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I would agree to try to get the ECU reconfigured to be a manual (along with the ABS unit and fuel computer). You will likely need access to a Tech2 to do this on a 2000 model - earlier variants of this engine with the DDE 2.0 need a Tech1/Tech1A, but they will be from around 1994/1995, and easily identified by lack of a MAF.
I am, however, surprised its running that rough, so worth checking for potential loom damage caused during conversion. From memory, there isn't a lot of wiring around the bell housing on those, except autobox loom, and crank sensor, but its been a while since I've been that close to one.
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Thank you for these anwsers.
That pin24 is shown as straight to ground if manual and if automatic it comes with signal? from auto control unit. So im sure that is good.
Now I have to find Tech2 with Opel/Vauxhall software card somewhere.
I have second Omega 2002 with 2.2 gasoline engine. With "My Naff Code Reader" you can just select from menu what gearbox it has. I tough that was same with M51 but it doesnt give that option at all.
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Thank you for these anwsers.
That pin24 is shown as straight to ground if manual and if automatic it comes with signal? from auto control unit. So im sure that is good.
Now I have to find Tech2 with Opel/Vauxhall software card somewhere.
I have second Omega 2002 with 2.2 gasoline engine. With "My Naff Code Reader" you can just select from menu what gearbox it has. I tough that was same with M51 but it doesnt give that option at all.
If you have the genuine version of op com then you could ask them if there are any options. If you have the dodgy version, I'd be *VERY* wary doing any configuration tasks with it - I've made a fortune fixing damage done by hooky version of that tool ;)