Need Help with Tuning Method – Dyno Runs and Lambda Readings

Hey everyone,

I’m currently tuning a motorcycle using Woolich flash, so I’m making changes between runs and not on-the-fly.

Here’s my current process:

I’m doing ramp runs at 100% throttle from 3k to 14k RPM, with 15-20% load to slow the run down a bit.

I have an O2 sniffer in the exhaust to collect lambda readings for each RPM range that’s in my fuel table.

The bike has dual injectors, so there’s a transition from primary to secondary injectors at higher RPMs.

The issue I’m having is that my adjusted fuel values don’t seem to affect the next run’s lambda readings as expected. For example, I ran a test where I increased the fuel by 10% across the relevant cells, but the resulting lambda values only shifted by 5-9%. I’m starting to wonder if the way I’m doing the runs (ramp runs) or the way I’m collecting data could be part of the problem, or if the transition from the primary to secondary injectors is causing inconsistencies.

Would doing stepped runs help gather more consistent data, especially across RPM ranges where the injectors transition? Or is this just something I’m going to run into during tuning, where results aren’t always 1:1 with fuel adjustments? Any advice or suggestions would be greatly appreciated.

Thanks in advance for any insights!

You say that you do WOT (Wide Open Throttle -- 100%) runs with 15-20% load. How fast do the RPMs change (i.e 500 RPM/sec)?, or how long are your 3k-14k runs (we can divide 11000 / time in seconds to get RPM/sec)?

You may get better results if you hold the sweep to 300-500 RPM / sec, so the O2 sensor has time to respond. If you can't run for 27 seconds, then you might want to do ramp runs over a shorter RPM range.

Thanks for the response. Looks like my runs were roughly 14s long so roughly 800rpm per second. My runs could be lengthened, Is there a sweet spot I should aim for?

try 400 or 500 RPM/sec.

When you say "O2 sniffer", are you talking about one of those with the long flexible pipe that you poke up the tailpipe? They seem to be common in the Harley world for some reason, but last time I saw a log from one it was obvious it had something like a 2sec delay so if that's what you have then I dont think I would trust it for anything but steady state tuning. That was apparently a "high speed" vacuum-assisted one too. I would be putting a bung in the collector if it was my own bike.

What bike and year? What actual Map are you changing?

This one is a 2011 suzuki gsxr 750. I'm just adjusting the fuel table.

Currently with the new load I'm running from 3k to 10k in roughly 24sec or 300rpm/s. I am finding that my fuel changes are sticking more to the cell that I adjusted. The percentages are still off. Adding 7% fuel resulted in only 3% increase in my lamda. Oddly enough at this particular rpm I'm running 100% on my primary injectors.