Hotwire

Hi all,

I'm hoping you can help me with some figures. I just recently tuned my friends Legnum VR4 (6A13TT) which has been upgraded with KKR 440 turbos, Sard 650cc injectors and numerous other supporting mods.

First of the rank, I adjusted the injector scaling to 621cc/min (DSM) 585 Evo scaling.
Latency values were set to:
4.7V - 6.12
7.0V - 5.616
9.4V - 3.264
11.7V - 2.136
14.1V - 1.344
16.4V - 0.912
18.7V - 0.456

With 20 mins cruising driving, then 16 minutes idling, fuel trims were LOW_4.807 and MID_0.101 - I thought Pefect! However, the idle is lumpy, fluctuation between 600-700rpm, and there is slight hesitation around the CL/OL transition point (70-80 load, 3000rpm) acccording to the driver (i couldnt feel it from the passenger seat). It was hard to measure AFR at idle (as on have tailpipe sensor, not bung in front pipes) but on cruise seemed to be at around low 15s at the tailpipe (seemed normal) and under load, was matching the AFR target map perfectly (initally 10's, then leaned out to 11.5 under full accelleration)

However the lumpy idle persisted. Now the only "spec" I have seen on the net for the Sard 650cc is 1.5ms latency - but no voltage given!?! (Part 63562 as per here

I have searched for hours on evolutionM and google for a similar spec injector and latency, to no avail. Can anyone shed any light on how I need to adjust the idle? My inclination is to bump up the latency as I think it *may* be lean at idle, thus rough idle. i.e. take the 14V value to 1.45 or even 1.5ms....

STFT Varied between 0 and 6-8+ but rarely negative, however. At cruise mid trim was 0.1 so i was very reluctant to change scaling, thus my thoughts it came to latency.

Other than that the idle, the car ran beautifully and went like a shower of ****, and on only 15psi was seeing 220 load pretty consistenly, but not sure of power or torque figures as we were road tuning.

Cheers
Lee

merlin.oz

Lee, try these latencys:

4.7V - 6.12
7.0V - 3.120
9.4V - 1.992
11.7V - 1.320
14.1V - 0.888
16.4V - 0.672
18.7V - 0.408

Mid trims wont move on that ROM, try logging MUT50 for fuel trim in use for cruising.

Nice setup, must have been a mission to get those turbos in there.

Hotwire

Thanks very much for that Dave. Can you explain the correlation between the claimed time of 1.5 and the voltage for me?
And my mistake, they were kkr280s, whoops :S

Hotwire

tonight I met up with the Legnum owner, and we tried the new latency values. While the LTFT LOW was initially better (1.474) the idle was still bad/lumpy. By the end of the night the trim was up to 2.062 and when in light cruise, there seemed to be +16% correction added consistently, so it was definitely lean on light cruise. Again though, under WOT, it was hitting the target on the map.

I took numerous logs of idle to try and determine what was going on, and it was clear that there is something going on with regards to timing. The timing was jumping form 0 to 20ºbtdc when the timing map clearly shows 8-10ºbtdc. Here is an example of the idle:


and when coming off throttle onto idle.


As you can see, the timing drops away to 0 then the car seems to catch itself adding 20 then jumping around again. Do you have any idea what might cause this?!

I have also attached the final log for the night showing that the correction was tending to 16%+.

If i understand the supermerge thread properly (and this post in particular https://www.evolutionm.net/forums/7704682-post8.html - "If your trims are negative that means you are rich, adding to the latency makes it more rich"). I have the opposite of this, therefore i'm too lean, and to richen I need to reduce the latency further, which means adding time to the 14V value??

Please help!




Cheers for the help and bouncing ideas - hopefully I can get this sorted for him as the driveability isn't great!!
Lee

Hotwire

BUT in relation to this, when looking back at logs from the original latency values, I also see the same +16% values for STFT and a LTFT LOW of 4.8%....




Now Im confused as to why it was suggested to reduce the latency values now, as surely they should be increased to richen the mix to minimise the +ve correction that was being added??

Hotwire

Anyone? The 50+ load at idle has got me stumped! :S