VE upper left quadrant

[msiddalingaiah]

I'm getting better at tuning my DR350s running MS-I fuel only.

I have a quick question: the original VE produced by the online VE calculator did a decent job with idle, but it had the same VE values for low RPM/high MAP bins (32%). This caused the engine to lean out, hesitate and in many cases die completely when I opened the throttle at any reasonable rate. I could compensate with accel enrichment, which worked BTW, but adjusting VE sounds better to me. What I think is happening is MAP goes way up (just about 100kPa), but the engine has inertia and doesn't accelerate fast enough for the mixture to keep up. I increased VE bins directly above idle RPM and to the right and that helped a lot. It seems the engine really wants a lot of fuel there. I compared my numbers with VE tables from other engines. It generally appears that many engines want twice as much fuel at 100 kPa and idle RPM, whereas my bike wants as much as three times.

Is this normal? It just seems unusual that my engine wants more fuel in that area compared with others. Has anyone else seen this? Should I be concerned or am I over thinking the problem? If that's what the engine needs, I'm happy to supply it. The fuel pump and injector have no problem delivering the juice.

I think everything else is fine so far. Any advice would be appreciated. I don't want to do anything wrong.

[flatbill]

I'm certainly no expert, but, if the motor is falling on its face it probably wants more fuel. What is your afr doing when this happens? On my setup I had a similar problem. I could watch the afr go leaner and leaner till it died. Try doing a data log and make it fail. Look at the data log and find the rpm and map readings where the afr drops off. Keep richening up in those VE bins and you should see quick results. Note that you should set EGO control authority to zero when tuning. I guess that if this is a bike you need to put your laptop in a backpack or something. Good luck. Billk

[msiddalingaiah]

Thanks! The datalogs show the afr going too lean. I richened up those bins and it's much better. I think I overdid it in a few spots as it too rich when I ride it. I was trying to get perfect throttle response on the kickstand, but I think accel enrichment is needed to do that. I rode it yesterday and logged it with PalmLog. It's rich, but not too bad.

At least it's ridable. Before I couldn't touch the throttle. Now that I can ride and log, I can improve it.

Btw, what's your manifold pressure at idle? I'm at about 70 kPa.