SimonR Posted June 24, 2007 Share Posted June 24, 2007 Reviewing my logs from yesterday at the Pod I noticed something that I must have missed before. On gear changes (auto) the AFRs go way lean – up to 17s – for about .3 of a second. Boost also dips slightly (about 3psi from 1/2 and about 1 psi from 2/3). I’m not letting off the throttle at any point and it’s a mechanical linkage so the throttle position isn’t changing and anyway the TPS output confirms that it’s wide open for the whole run. So it’ll be something buried in those cunning internal maps somewhere, then. I assume that this is intentional and therefore nothing to worry about (?), it’s just that looking at a log that says that 17.7 AFR at 100% TPS and 12psi goes against the grain somehow. I’ve heard anecdotal opinion about gear changes involving timing retard and my logs show an apparent pulling of fuel, but does anyone know exactly what the ECU is getting up to during auto gear changes? Link to comment Share on other sites More sharing options...
TrickTT Posted June 24, 2007 Share Posted June 24, 2007 The second butterfly in the throttle body, which also does the traction control, closes during autobox gearchanges to take the load off the gearbox, and the ecu acts the same way as it would if you lift off the throttle - ie knocks off the fuel for the duration of the change. Thats why its not a good idea to remove the stock TC on an auto. Link to comment Share on other sites More sharing options...
paul mac Posted June 24, 2007 Share Posted June 24, 2007 do you still have the TC butterfly fitted ?, the definative way of proving whats going on would be to remove the butterfly and unplug the trac ecu then Pod/log again, i have just got round to removing the trac ecu myself the butterfly was junked about 8 months ago and i am not noticing any difference in full throttle gear changes with regard to timing retard Link to comment Share on other sites More sharing options...
SimonR Posted June 24, 2007 Author Share Posted June 24, 2007 No second butterfly on my car - no TRAC. Thanks for the replies, though. Link to comment Share on other sites More sharing options...
paul mac Posted June 24, 2007 Share Posted June 24, 2007 No second butterfly on my car - no TRAC. Thanks for the replies, though. cant really help simon but that is interesting that you have the trac disconected as every thing i had read indicated that it was the trac ecu doing all the cunning stuff and with the amount of connections on the trac ecu plug i just presumed wrongly this was the case, as you say it must be the main ecu, how were you logging all this Link to comment Share on other sites More sharing options...
SimonR Posted June 24, 2007 Author Share Posted June 24, 2007 how were you logging all thisemm.exe logging from Emanage. Export results to CSV then PERL script to convert the recorded voltages to useful values. Sometimes I feel like a proper tit. I can't believe that I posted earlier that presumably the ECU was pulling fuel. The very same logs that I was looking at also contain the stock injector values in ms and %. D'oh! At the same time that the AFR's increase, the stock injection is reduced by quite a margin. There's a surprise! So, in a way my first post was correct - that the internal maps are pulling fuel so I suppose that just leaves me wondering whether I should be concerned about the high AFRs under high boost. I guess not, as that's the deliberate situation from the ECU. I was wondering why the ECU threw so much additional fuel into the mix at about 4,000rpm and above under WOT. Maybe this has something to do with it. Link to comment Share on other sites More sharing options...
paul mac Posted June 24, 2007 Share Posted June 24, 2007 i guess the only way to disable all the stock ecu's little tricks is a standalone ecu ££££££££££ Link to comment Share on other sites More sharing options...
SimonR Posted June 24, 2007 Author Share Posted June 24, 2007 I can think of better things to do with a couple of grand! Link to comment Share on other sites More sharing options...
paul mac Posted June 24, 2007 Share Posted June 24, 2007 I can think of better things to do with a couple of grand! yeah me to mate, good thread i think its put my mind at ease a bit with regard to junking all the trac stuff Link to comment Share on other sites More sharing options...
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