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Motec M600- increase in fuelling

Practical Standalone Tuning

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I have a race car that I mapped at the start of the season and just tweaking the fuel and lambda control during the year. It has been fine and been getting better but all of a sudden the close loop has now maxed out and its roughly 10% rich in most arears of the MAP. The coolant temp compensations are zero during operation and the air temp was 24 average when running rich, 29 when it was working fine. My air temp compensations are 0 at 20, -2.5 at 30, -4 at 40. When I mapped it, it was about 37 degrees (I'm guessing I could have been a bit more aggressive with the compensations) could this be an issue? just 5 degrees cooler? Or is there something I'm missing?

Its a BMW E46 M3 S54, Motec M600. Attached is the base MAP and a screen shot of the logging, the log file is huge so will send it if someone wants to take a look. The circles on the screen shot is the lambda control, it runs two different throttle maps for different races, the ones circled are all the same map.



Attached Files

Well, you can see the duty cycle is higher, the question is why? Would need to look at the logged data file for additional clues. I suggest uploading it to Google Drive, or Dropbox and posting a link so we can download it.

OK, I think it's because your Adjust->Fuel->Compensations->Post Start Comp table has a value in the 20 sec column when the Engine Temp Comp is close to zero. When the engine is started warm, the Engine Temp Comp is 0. So this table will add 50% fuel (notice is has an asterisk indicting it was changed). I think that table should taper to zero in the right-most column. You want to exit the table (as the run time exceeds 20 seconds) with no compensation under all circumstances.

It does not look like you can log/View the Post Start Compensation, but see if Fuel Starting Comp has a value in the View Screen on the Fuel Tab after the engine starts, if it does add that to the logging (its in Fuel Detailed 2).

Any chance that changed between the earlier runs and the later ones?


Yes it was the only thing that had changed, I will get those changed back. It was away with someone else who couldn't get it started so they played around with all the cold start figures. I dismissed those figures as I didn't think they came into play during normal operating times?

I have attached an earlier base map

Attached Files

Thanks David, It was just that one figure on that Post Start table.