Misadventures in tuning

Kinja'd!!! "RiceRocketeer Extraordinaire" (ricerocketeer2)
09/04/2013 at 20:04 • Filed to: None

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For years I thought my car had bad heat soak — the throttle would go weirdly soggy on hot days. Turns out the programmable ECU was incorrectly retarding ignition timing at low engine loads instead of high loads. Moral: if you put something tweakable on your car, be prepared to get fully edumunkated about it.

The stock tune (and all tunes I've seen) retard ignition at high temps and high loads to protect the engine. For some damn reason the values were also swapped or copied to the idle/low load table. The car had been dyno tuned at a reputable shop, but even so their focus was probably more on power than drivability.

Seriously, this caused me to buy and swap parts in and out, tweak the raw ignition timing tables, and even buy a 2nd car so I could drive something that didn't stagger around like it was punch drunk.


DISCUSSION (4)


Kinja'd!!! Casper > RiceRocketeer Extraordinaire
09/04/2013 at 20:09

Kinja'd!!!0

Good lesson right there. Sorry to hear it was such a PITA though. That is one thing I will have to do when I switch my car over to the standalone... go through everything myself while also having other sets of eyes check it. It seems like I look right over issues simply because I wasn't looking specifically for them.


Kinja'd!!! webmonkees > RiceRocketeer Extraordinaire
09/04/2013 at 20:41

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I lucked out in that the Golf/Jetta digifant uses a real simple chip that somebody figured out early on.

Programmed right, they can do wonders. Wrong sensors or programming, pig. Is that a verb?


Kinja'd!!! The WB > RiceRocketeer Extraordinaire
09/04/2013 at 20:45

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Yeah, most chassis dyno tuners don't even look at bins below 90% throttle. You can get them to part-throttle tune, but that takes a LOT of steady state work and a lot of hours best suited for an engine dyno.

A couple weekends with the laptop and it'll be great. That looks like my PE3, if it has data logging, that will be your best friend ever. I actually wrote some VBScript for my Mustang that will pull out and bin/average AFRs over the drive and output a resulting measured AFR table.

Much easier than slogging through the lines of the data file to find that one time you got on it or coasted down. That way you can tweak those soft spots or sputters out, and all you have to do is go drive it around then download it and look.


Kinja'd!!! VincentMalamute-Kim > RiceRocketeer Extraordinaire
09/04/2013 at 21:54

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That's what irks me to no end about paying professionals to do anything. They'll screw it up just as badly as you can screw it up yourself. That's led me to try to do everything myself. Then when I screw it up, at least I've learned something. Tuning ECU's isn't something I've learned though.