I would like to hear from all those who have tuned up any stand alone EFI fuel map. I guess from the limited response to the survey of EFI slants owners there are not that many of us, but let's get together here and share in this. I am not completely happy with my process, but it has worked OK. I basically redid everything from the Dyno shop. I considered that pretty much a complete waste of money because the intercooler was not cooling as they tuned.

I will start: Lou ws the first to help me tune the Mega Squirt, and I have pretty much followed his lead since. I have several friends who understand this system, and they ride shotgun with the lap top in their laps, hooked up to the ECM in tune mode. We open the VE table, which has the cells for various operating conditions, RPM along the horizontal axis and MAP readings along the vertical axis. I use KPA (which is metric) scale since the numbers are linear and progressive in the same direction from full vacuum to full boost.

AS we drive around, the copilot rides shot gun, and increases the VE number in the cells based on how the car seems to be running, and on the readout from the O2 sensor. If it bucks or surges, then this would indicate either too rich or too lean, and the O2 reading is the guide. If the O2 reading is below .5 then the co-pilot will tick a few extra points into the VE number of that particular cell to enrich the mixture. It the O2 reading is above .5, then the VE number is decreased. There is no essential difference between the MEga Squirt process and the Accel one, accept there is a little more sensor feedback available on the screen for the Accel.

Within a certain range, the car will run OK, even if it is not ideal, so the first goal is to just keep it running, and to have the transitions from on, and off throttle to be smooth. What we have discovered with my set up is that for the higher KPA numbers that are still not into boost yet, O2 readings between .7 and .8 are OK. For low KPA numbers, which would be high vacuum, if the O2 readings drops below .1, the engine is likely to die. Anything above .2 is OK, but .3 seems to be the best for light drifting. .4 seems to be good for the light throttle cruise, and .5 to .6 seems to be the best for slight up grade cruise.

One of my co-pilots is a very sharp guy, who has been into motorcyles for awhile. He is very sensative to how the car feels and seems to be running, and was very good at this process. He thought intelligently about what he was doing, and seemed to have a great time. The car ran much, much better after his stint at this.

I haven't touched the car since the weather turned, and some of the mods I am going to make will involve recalibrating some of this, so I will be at it again some time down the road.

I suspect I will be able to trim some of the numbers down a bit for economy once I get some more time it.

I know some of you have gone through this same process using data logging. Would you, or could you, take the time to give a short description of how your process worked, and what you were looking for in your tuning. Also, any and all comments that might improve upon the procedure, or increase our understanding of what we are doing here would be welcomed. particularly if you have comments about the numbers I am using as guidlines here. I am open to enlightnement, and learning. Thanks guys.
Sam

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Are those numbers raw voltages from a narrow band sensor?

Mine is set up with a wideband sensor, so my numbers aren't directly comparable, but I've been going for 13:1 under acceleration without boost and maybe 15-16:1 under high vacuum. And around 11:1 under boost.

Also, my slant seems to like a slightly rich mixture at idle.

I'm planning to dyno tune mine. That way I can hold it at a steady value and don't have to worry about acceleraton enrichments. One tip I picked up at EFI101 is that it's usually best to turn acceleration enrichments off when dialing in a VE table.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Thanks for the tip Matt. It makes sense tht the acceleration enrichment should then be applied to a base VE table. That is what they say about everything basically. Matt, would you describe your tuning procedure? Do you use a co-pilot, or dat logging. If data logging, what are you looking at, and what sensors are you requestiing the data log on? I can;t rmember how MS is configured on the data log.

But if you turn off acceleration mods, how do you interpret the feedback. Do you just allow a momentary bog knowking you will fix that later? Yes, these are narrow band numbers. I don;t trust the feedback from my wide band. In talking to another EFI geek, he said it is his practice to take out the wide band and plug the bung when not tuning, since they seem to go bad fairly quickly. This is just what he says. I don;t have an opinion right now. I know mine did seem to go bad after about 18 months.
Sam

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