MSefi.com read only forum (Jan.15,2018)

Running MSII, v3 with ignition and fuel control. Using Megatune and Tunerstudio also. I have a problem on the dyno when I start to load the engine where the torque band comes in. I am getting severe lean spikes when I load the engine above about 3800 RPM. The AFR and VE tables all look correct but I am getting lean spikes. I use a wideband Zeitronics O2 sensor. I have attached two datalogs; one is at low speed where everything looks normal and the other is where we load the engine. Can someone take a look at these and give me any ideas? I can provide whatever additional information is needed to help in this matter.

Thanks in advance,

James Thomas

I can give you some ideas of what to look for. The problem happens as you go past 3800 rpm. Does the pulsewidth go up, down or stay the same. The two primary things that affect Pw are MAP and VE - does the pw track with these - as your load goes up so should MAP and fuel - unless it is peaked out. VE should also go up. If you step it up does PW follow. Look at your rpm - does it ever go to 0 indicating loss of synch. Now look at the enrichments - especially accel/ decel - are either of these taking away fuel (they shouldn't be under load, they should be adding to pw). But if you are using x-tau and it's not set up and tuned right it can sometimes reduce fuel. If your PW looks good, then verify your WB by verify that it goes up or down at roughly the same %, on average, as your PW.

Thanks, I will check out all of that. Did you look at the datalog? Maybe I will get educated at the Megameet.

James

You are going from accel enrich to decel and back and forth. It may be that the sensitivity of the TPS is too much. In accel enrichment there is a setting called TPSdot that you can set higher to lower the sensitivity. I had to set mine as high as 30 to stop inadvertant accel/decel. The manual says to set it artificially high so that the enrichments don't happen until you have your ve table set correctly. Also, it looks in the other datalogs that you have way too much variation in the map reading that is increasing the pw for no apparent reason and may be leading to a rich missfire giving a false very high afr reading. The map signal should be way steadier than it is.
Paul