Saturday, February 14, 2015

MegaSquirt Cold Start Up

Those of you that think you have great drivability, check out this video from early Friday morning. 

My other car was showing 9*F (with 20-30mph gusts), the coolant temp was in the teens (you can see it fairly clearly in the video, it was almost 40*F during the day so I didn't expect the engine temp sensors to be as cold).  If I’m really careful I can get going and run it through the gears without using the gas pedal and stalling, even when this cold, but I wasn't going to try while shooting video.
Cold Start- 87 Trans Am + Megasquirt

  • 87 Trans Am
  • LB9 engine – 305 TPI with _a lot_ of miles on it (it gets <800 miles to a quart of oil) the odometer reads >120K miles and I’m not sure if it’s correct
  • T5 transmission (5 speed manual) which a previous owner put a lightweight Kevlar flywheel/clutch assembly in that did nothing for smooth driving.  With the stock ECM/tune it would try to stall all the time unless you gave it a lot of throttle, even in warm weather, even when warmed up
  • Megasquirt 2/PCB 3 running MSExtra firmware
  • It’s running my 93 octane “race” tune on 87 octane.  I quit loading the 87 octane tune after I got the knock sensing/retard working really well. 
    • It has run 13.6@99.9mph in the quarter at the track recently with this tune.
    • It seems to be averaging 22-24mpg in mixed driving (DC metro doesn’t have true “highway” driving until you get quite a bit out of the area, traffic just sucks).

I keep hearing people that swear by carbs say that they have drivability as good as any EFI car.  I’m pretty comfortable with carbs but I can’t make one run like this and I’ve never seen one run this well.  Maybe just when it’s cold, warm, economy, driveablity or performance, but not all of them.  Typically this lean a mixture will want to surge and buck and won’t make best power (though they’re not incompatible with a carb because they’re in different ranges), and if you richen it to get the driveability you loose MPG.

The funny thing is that this car does less weird stuff driving around than my 2012 SHO, well at least the engine... the rear axle is another story.

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