Yes. Its a night and day difference! When we pulled the stock headers off the car, the fabricator (with 40+ years of race car building experience) said these belong in a small displacement (<2L) I4 or I3 engine, not an H6.
I've logged the trip up to Danbury (before) and trip down back to New York (after) to get a direct comparison of logs. I've also logged some more Sunday and Monday to see the after trends continue.
Here is some feedback I shared with the tuner; Rob @ AMR:
· Fuel Trims cleaned up nicely - within 0-10 (usually 0-5%) for Bank1 and -5 to +5% for Bank2.
· No more excessively rich measured AFRs (vs. what's commanded) under WOT - nothing south of 12:1.
· No more negative timing data points (not even any transient blips).
Fuel Trims - much improved (even vs. just adding the honeycomb airflow straightener)
15% throttle and up, they’re almost always within the +/-10% bracket, both banks.
Looking per bank at both LTFT and STFT, you can see how the STFT adjustment swings are smaller.
Far fewer cases of the larger negative STFT swings. If anything I see a few more positive STFT swings.
Even fuel mileage seems up (I’ve gone through half a tank with some spirited driving since leaving Danbury and I’ve clocked 250 miles thus far; that’s ~32.3mpg!)
Of course I’ll monitor this more over a few tank-fulls.
*We forgot to tweak an inherent fuel trim offset we see between Bank 1 vs. Bank 2. Ecutek software usually commands changes to Bank 1 only but there is a way to force a hard adjustment factor to Bank 2 for some compensation. Its decreased a LOT from pre-header tunes to a point that it’s almost gone. But, I wonder if getting rid of it would net more power or just a sign of an injector performance difference in one or more of the cylinders between the banks.
AFR - also improved (leaner under load). I don’t see any more dips into 10.x:1 rich territory.
15% throttle and up, the richest it got was 11.93:1, typically in the 12.5:1, very close to what's commanded.
Timing Advance – has generally gone up. And no more pulled timing! In fact, I see positive timing advance even under WoT.
While cruising, I can typically see +35-40 degrees now. Plenty of +40-45 degree data points.
No negative timing values! Under WOT the lowest I see is +4.5/5.0 degrees!
Seems like it hit that a few times. Before the headers and re-tune, we had a few random -5.0 degree data points.
MAF – no issues. Still rock solid at idle. Since you rescaled the sensor (changed transfer function?) I’m seeing lower g/sec ‚readings‘. With the new scale the highest I’ve hit is ~208g/sec.
IAT vs AAT Temps are still good – now that its gotten colder, I get within 2-5F of reported ambient while cruising.
After a trip, when the engine heat soaks, the intake only reaches about 110F (used to be 140-160F)
and the intake temp drops back down below 70-80F much faster once you get going.
Data log plots attached:
This is all >15% Throttle Position to remove low throttle, low load noise.
Legend:
SATURDAY AM (BEFORE HEADER INSTALL): 1st section, to the immediate left of the red vertical line
SATURDAY PM (AFTER HEADER INSTALL): 2nd section, to the immediate right of red vertical line
SUNDAY AM/PM (AFTER HEADER INSTALL): 3rd section, last continuous section of data toward the right (180K to 225K on x-axis).
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