MoTeC Global Forum

Hi all,

I own an M400 ECU that I'm using on a turbocharged Scion tC. Everything is running great, but I'm stuck in open loop. I'm using a Bosch LSU4.0 wideband sensor for reading out lambdas in the ECU. The problem is that I seem to be getting an "intermittent" connection. Check out the log I included (ignore the oil pressure error). I had a problem with loose crimps before causing intermittent camshaft operation, so I'm thinking I have the same issue with the AFR sensor. I've tried three different sensors, so that isn't a concern.

Any advice on what to test to isolate the problem?

All I can tell you, which you probably already know, is that the lambda sensor is in error the whole time. 'e' key in i2 displays the errors at the top of the screen.

In ecu manager, go to data logging setup. Under diagnostic errors 1, log error group 7, which is mostly lambda stuff. Also log everything you can find for lambda 1, under lambda sensor detail, maybe log sensor supply voltages as well. Possibly you can log the voltage on the aux output you have configured for lambda heater, under output voltages 1

Then you can give it a run again, and look for more clues, or post up here, whichever suits.

ECU config would help diagnosis. I don't think it's a faulty/broken wiring issue, but I'm no expert. Is this a new setup, or one that worked and now does not?

Thanks for the help.

Looking at the earliest logs I have, it would appear this has always been a problem since I purchased the car. The car still runs pretty solid in open loop though. I also have a log from when the car was first tuned. At that time, the lambda signal was reporting correctly and the car was in closed loop.

I'll have to get back to you with more logs. The ECU is password protected - so I'm going to have to do the run around with the guy who tuned it like 5 years ago. Very aggravating.

LSU 4.0 data sheet here so you can check the wiring pinouts. What is the sensor part number?

http://www.motec.com.au/filedownload.ph ... docid=3523

I believe the part number is 101061.

I did some testing using that pinout, but I'm not completely sure what values I should be looking for. For example, am I correct in thinking the heater+ wire should have a constant 12-14v and switches on by grounding the heater- wire? I also don't have a voltage table for the AFRs. I did probe the Vs wire though (which I believe is the signal wire), and it showed a constant 1.5v - which can't be right. Continuity checked out on each wire though (measured post connector to connection at ECU).

Still working on getting access to ECU logging options in the meantime...

focus_sh1ft wrote: For example, am I correct in thinking the heater+ wire should have a constant 12-14v and switches on by grounding the heater- wire?

Yes, the lambda heater defined aux ouptput switches to ground.

You probably need to double check the actual part number on the sensor, that number doesn't sound like a Bosch number??