LTCD strange behavior

Discussion and Support for MoTeC's M1 series ECUs

LTCD strange behavior

Postby OlegD on Tue Aug 10, 2021 9:09 pm

Hi, I'm experiencing strange LTCD issue, it was ok before. It's impossible to switch lambdas in this configuration without pulling the engine. M1 GTR package. Where to look for the problem? Or the sensor is dead.
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Motec lambda - Copy (2).jpg
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Re: LTCD strange behavior

Postby David Ferguson on Wed Aug 11, 2021 1:23 am

Seems obvious -- bank 2 Lambda sensor. But could also be a broken header or other exhaust failure upstream of the sensor.

While you have the engine out, perhaps you could relocate the sensors bungs in the exhaust to make them more replaceable (like by just removing the exhaust).
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Re: LTCD strange behavior

Postby OlegD on Wed Aug 11, 2021 10:06 am

David, very strange thing that it works sometimes. Exhaust is fine as well. I'm more inclined to think that this is the wiring issue and not a dead sensor. Car was totally fine a few weeks ago on the dyno and didn't move anywhere waiting for the fuel pumps.
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Re: LTCD strange behavior

Postby David Ferguson on Wed Aug 11, 2021 10:57 am

Any chance your wiring has melted on the exhaust?
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Re: LTCD strange behavior

Postby SDean on Thu Aug 12, 2021 11:25 am

Can you log all of the channels for the two LTC's and post it.
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Re: LTCD strange behavior

Postby MalcolmG on Thu Aug 12, 2021 1:55 pm

Any chance the lambda sensor is too close to the alternator? I've had intermittent issues like you describe in an application where the sensor was about 50mm away from the alternator; changed sensors 3 times before clocking it 180 degrees around the pipe and the problem went away permanently.
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Re: LTCD strange behavior

Postby OlegD on Tue Aug 24, 2021 12:46 am

Log attached. Maybe that's fuel contaminated with some additives? It's a strange batch of "e85" blend supplied by one company, that shows "ethanol" content as 106% now. Some Methanol?
New spark plugs, leak tested the engine, checked the exhaust, wiring. All seems to be ok. No audible knock.
Alternator is far away. Wires not melted.
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S1_#839_20210803_140933_EXPORT_LAMBDA.ld
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Re: LTCD strange behavior

Postby SDean on Tue Aug 24, 2021 8:28 am

Water contamination of ethanol can also lead to the sensor reading more than 100%.
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