Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Monty Takes A Deep Breath

I'm in Rickmansworth Andrew, so 35 miles from Surrey Rolling Road, I do all my own ECU calibration work (mapping) on the road and track, so I don't really need a rolling road for tuning. I use Surrey Rolling Road just to get a number, they offer what they call 'Shootout Saturdays' which is one run on their respected dyno that's known to give accurate and repeatable horsepower, torque, and lambda data.

I will also be using the run to safely record another high rpm log, I can then compare this with what I recorded at Castle Combe, they are two very different environments but the data should correlate. When I discovered Monty was dog rich at the very top end, I ran the AutoTune feature in my EMU Black software that suggests what VE numbers are needed to get the fueling to hit the lambda target, which in this case is 13.0:1.

AutoTune then gives you the option to apply 100% of its suggested corrections, or 50% of them. Because I'm working in the full load high RPM area of the VE table I chose to apply 50% of the suggested corrections, so my VE table is actually still 8% too rich at the very top end, this seems counterintuitive but it's done for safety.

Here's the rich VE table before correction, and with the problematic cells highlighted in the top right corner.





And now with 50% of AutoTune's suggested corrections applied.





My Bosch LSU 4.9 Lambda sensor is now back in stream (yes it fixed itself), so I've reinstated closed loop fueling (short term fuel trim), but now with 20% correction authority either side of the numbers in my lambda target table.



In the case of the 8% too rich top right corner of my VE table short term fuel trim with my new increased 20% correction strategy now has plenty of authority to correct the 8% over-fueling and pin the 13.0:1 AFR target. If the lambda sensor ever did go down again, which it shouldn't now there will be no over-fueling, all that happens is the ECU falls back on the 8% rich VE number in the base fueling table (the VE table), and the engine will see a very safe 11.80:1 AFR.

If you're local to Surrey Rolling Road and you'd like to pop in to see Monty on the rollers next Saturday, you'd be most welcome, it would be nice to meet you.

Dave.