The moderator at EFILive (joecar) took a look at my tune file, and made some suggestions to me on some tables to take a look at for the rough cold start idle problems I've been having. Seemed like rather minor changes, but they made a world of difference when I loaded the tune that I modified with these changes.
Start up is MUCH better. Doesn't try to stall out on me and run extremely rough like it used to.
The changes made were:
B3618 - increased richness of cells below 1600 rpm.
A0002 - set percentage to 100%
A0008 - increased commanded fuel multiplier at ECT values below 90 C.
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I think A0008 was probably the table that really made all the difference, as at idle, power enrichment isn't even being triggered. I may take the car out for a spin to see if the changes to B3618 made any difference to throttle response. I'm thinking a bit more fuel might help, since from what I've seen of the logs I've taken, throttle blips tended to make a lean spike and the A/F ratio.
The cold start tuning has been coming along pretty well, so I made up a video showing the progression along the way.
I was feeling pretty good about the progress I made when I started up the car on Saturday morning to go along on a cruise up to Thomasville. In the past when I would start the car up, I would just leave my foot off of the gas pedal completely the entire time till I let the car warm up a bit, but this time I goosed it a little bit and the engine just fell right on it's face when the rpms came back down to what should have been idle speed. So yesterday I set up the laptop for logging and also had video running when I did another cold start to check out this problem. I then took video off of the laptop and merged that video with the audio of the car actually running so I could watch the log data while listening to what the engine is actually doing.
So apparently I still have more work to do in this department concerning the cold start process. The engine is running in open loop at this time, so I need to figure out what tables would be active when the engine is coming down from an abrupt blip to the gas pedal and try to compensate for this transition that allows the rpms to drop down into a stall.
Well, the most obvious event I can see when the engine stalls after the throttle blips is that the throttle blade opening goes from the normal 17.3 percent down to 14.1 percent, so apparently the engine is starving for air flow, which chokes the engine at the lower ECT (engine cooling temp) levels. Once the temps reach a higher level, then that throttle blade choke doesn't affect the engine as drastically.
So, I just need to find the table(s) that will get that throttle blade to come back down and STAY at 17.3 percent after the jabs at the gas pedal.
I see a second career as a tuner in your future, Rich! You would probably
be better than 90 per cent of the guys out there........
Andy
Thanks, but nah, not my cup of tea. I'm not about to pretend I know what the heck I am doing with this stuff.
Besides, I would need to have access to a dyno, and that certainly isn't going to happen. I only know of a two places with dynos around here and I'm not likely to ever step foot in their shops again.
Location: 25 miles south of Boston, MA. Also have a house in Dunedin FL.
Posts: 1,927
Name : Andy Anderson
Crawfordville Timing Association and Dyno Tuning Facility has a nice ring to it!
Just think of the sign........R. Zuchowski, Prop.
Makes you wanna jump right in there don't it!
Andy