So it sounds like the Lotus ECU is basically a pain to work with. Since I've found no info from searching, I'll ask: "how
does the Lotus T4e function?" Fuel and ignition tables as a function of MAF vs. RPM vs. IAT vs. PSIambient? How does it use its knock sensor; in a "ping and retard" method or off a base map with knock retard in the background just in case? Does closed loop operation occur only below a certain MAF, or MAP, or ??? Subsequently, does that fuel trim get applied to open loop fuel values? Basically, how does the Lotus ECU "learn"?
charliex's explainations about how
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Originally Posted by charliex
the math would have to be identical or it starts to drift, ...., you'd need a way to be sure it was following the right breakpoints
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would be appreciated to be expounded upon. What do you mean by breakpoints? Datapoints within tables, or other variables? I'm sure he has to know what he's doing or there would be lots of Katana's out there going ka-blam-o. I see charlie making lots of comments about everyone reading AFR wrong, yet on his Gotham site he shows two dyno charts with AFR's, both of them unwisely lean for the vast majority of boosted PFI setups I have experience with to date [assuming the AFR plots are cars running E10 and the WBO2 measurement is pre-cat]. I'm not attacking charlie, I'm just looking for clarification to improve continuity. I have seen independent dyno plots of his ECU tunes with some very nice AFR traces, so I know the goodness is out there, it's just not cool to have bad examples of your work on your main site.
--->Charlie; what are your AFR targets [versus RPM @ WOT] for boosted applications for E10 91 [R+M]/2? Being that the Lotus market is very limited, and thus the knowledge base getting any and all the info they can, it's easy for people to grasp onto "theory" they've heard without learning the hard way. With any PFI setup running our American E10, peak torque ranges from 12.3-12.7:1 AFR pre-cat [which is a half point off the traditional 12.8-13.2:1 with 100% gasoline, of course]. Now, running a boosted setup, especially one at or over 20:1 dynamic compression ratio, demands at least a half number of richness for chemical quench, with a full number the norm. This means real AFR targets for boosted PFI is 11.3-11.7:1 AFR with E10. Of course, for the few people that run 100% gasoline, we can lean that out a half number because the lambda is changed accordingly. I see no reason the 2ZZ-GE is a special case to run AFR's any differently, unless you have knock data to support running leaner during durability testing.
I have experience with tuning many boosted applications, from SRT-4 to STI to Evo to 1st and 2nd gen MINI to carburated American V-8's with BDS 6-71 and 8-71 blowers. Everything from Alpha-minus to closed loop WBO2 MAF/MAP hybrids and K03 to GT35R, so please don't take my questions as a knock or diss, and more of a request to be on the same page.
Finally, I would like to discover how to effectively control the 2ZZ-GE in the Elise/Exige through different hardware configurations. Is running something like an AEM ECU running closed loop WBO2 controlling fuel and spark while the T4e sends CAN to the dashboard a reasonable solution? Does anyone else have an cracked Lotus ECU product, or perhaps charliex is working on such a product for custom applications? Hardware-wise I see nobody working on a twin-screw supercharger, which is tragic since they are so much more efficient than the piggy roots blower.
Thanks and Peace,
Ryan