Greg G

I swear the new cams have had a huge difference in the idle characteristics of the car! The increased air has allowed me to turn down the PID settings a LOT! I cannot even feel it when the AC compressor engages anymore, and turning on AC plus headlights is just a small smooth dip which normalizes immediately. With some more tuning, I may even be able to get rid of the extra solenoids.

RPMdot is more erratic now due to the cams, which is mainly the reason I cannot run extreme D anymore.



Logs here:
https://www.miataturbo.net/showpost....0&postcount=29

gslender

iTrader: (1)

What brand/type or profile cams? They sound like they've helped a fair bit!

G

Greg G

Maruha NA6 f-cams. They are mild cams, meant to be compatible with the stock ECU and valvetrain. 252 in/256ex, 8.5mm lift. I installed them for a better midrange, and was pleasantly surprised by the effect they had on idle (well after an initial shock at a horrible idle, due to wrong timing sync).

gslender

iTrader: (1)

Cool. Where'd get 'em from? Also, not concerned about adding too much overlap (normally a bad thing for FI engines) ??

G

Greg G

Got em from Tetsuyagarage in Japan. Still tuning the cams, we'll see how it goes...

Greg G

I switched back to standard firmware with 3.1.3 beta, from 3.1.1 mariobv17. Loaded up my current msq-- look what happened to the idle duty!



Reduced D from 3000 to 200! I guess D is amplified ~10x!
Much better. Need to retune my VE table a bit. Gve is moving too much.

JasonC SBB

He's got cam gears so he can dial in any overlap he wants.

JasonC SBB

I think the mild overlap you tuned in, plus late intake closing from the duration, means the engine will idle at a higher MAP. (you reduced idle VE). With increased MAP in the intake tract (throttle volume), the feedback control system is more "linear" because operating the solenoid at a larger opening means air can get through more quickly as needed to catch an idle dip. This also means less D is needed. More MAP means more air is available in the intake tract if the engine suddenly needs it.

gslender

iTrader: (1)

Sure. My point was more that any overlap increase is generally robbing power elsewhere in an FI system. Normally you'd add cams that reduce overlap, not add it (which is opposite of what you'd do for a NA engine). Under boost, that overlap is allowing air to escape out the exhaust.

Lift is a good thing either way.

G

Greg G

I found this to be interesting reading:

http://www.superchargerperformance.c...and-cam-timing

gslender

iTrader: (1)

So, what's your thinking? Gonna dial in some major retard (to combat the extra overlap from stock) or try first and see if it "feels" the same....??

I'd be keen to know as I'm working towards a turbo but will go Cams first and intend on getting 10mm lift with aggressive overlap, but will use Adj cam wheels to dial that out (and more) once the turbo becomes a reality.

G

Greg G

Rassa frassa ^$^&$

Discovered why my idle droop was gone-- the AC fan relay trigger was grounded and in turn triggered the compressor! So that's why my base MAP was so high, ~50. The rewiring was done at the same time as the cams (I never learn do I).

Aaaanyway, fixed the electrical issue- base idle MAP went down to ~40. And surprise surprise, AC engagement causes some droop again! Not as bad as before the cams, but I will have to ratchet up the D value. Right now it's a tradeoff between killing the dip completely and having a twitchy idle, or allowing some dip and have a more sedate idle. Trying to find that balance now...back to PID tuning! >.<

P60 I80 D600 min 900 max 1650 idle duty range: 25-80

gslender

iTrader: (1)

Why not try my idle up code and perhaps this might be the solution to solve your idle tuning nightmares ;-)

http://www.msextra.com/forums/viewto...299164#p299164

Greg G

Hey yeah I saw. Will give it a shot when I get some car time. Will require some rewiring to move control of the AC to an output controlled relay, but I can try it to see if the hardware triggered idle increase works! When I get some car time..this coming week is gonna be brutal for me... :P

Greg G

Since I'm stuck at home, I was playing with my AFR tables.

Went from the one on the right to the one on the left. Comments are welcome

Greg G

Oh my this brings tears to my eyes...



Hope it works

How exactly is this calculated? It adds the percentage adder to the final calculated duty? Trying to figure out how this will affect the PID code when active...does this also affect the dashpot adder?

richyvrlimited

iTrader: (1)

Damn you work fast!

I've filed you under the legend pile with Joe Perez and Reverant now

Greg G

I know right! What a weekend!

gslender

iTrader: (1)

Easy boys!

Greg G

It freaking works!!!!!!