MS3 ITB mode load spikes

[aikendrum105]

Hi all,

having a curious issue with load spikes at WOT.. I've attached my tune, a logfile and a screenshot of the load spikes/ripple I'm talking about. Basically I can be at WOT and in the 4500rpm onward range suddenly have a massive lean misfire (never fun) which baffled me for a while. Take a look at TPS, MAP and LOAD.

However I've noticed a couple of things - first is my barometric pressure seems to be zeroing out 93kpa - this logfile was taken at Phillip Island racetrack - it was more like 103kpa according to weather report for the day. I have a feeling this baro error added to the ITB switchpoint set at 92kpa, and the almost imperceptible ripple/noise on the MAP waveform in sync with the strange load fluctuations is the root of my problem - but I thought I'd run it past you all to see what you thought..

In playback of the log - you can see that load fluctuation dropping VE / Ignition down in to the bottom third of the table - causing the lean events.

MS3 + MS3X with mapdaddy dual sensor, knock sensor and rtc modules.

Appreciate all help and criticism as always.

Cheers,

Scott.

megalogviewer390s.png

[jsmcortina]

Is your "TPS switchpoint" curve set correctly? If it is then your throttles are massively oversized.

Your datalog doesn't include Baro, so I can't asses what is going on .

James

[aikendrum105]

Thanks James - I'll take another log incorporating baro and upload. What a duffer !


Yes, they're 38mm throttles with open stacks feeding stock intake ports and cams on a 2L Alfa TS. They are well oversized for the current engine build.... the engine under construction will breathe a little better though...

Cheers,

Scott.