soslo

iTrader: (12)

So I am tuning my Heads/Cam/Exhaust car (starting from the stock tune). I have a wideband O2 sensor welded in, using the LC-1. With the stock tune, the A/F ratio is typically between 18-19.

And all of the tuning info I've read says that the VE table needs to be scaled something like 70/80/90 in the 4/8/1200 rpm ranges due to recursion.

Also, I've read to shoot for approx 15:1 idle A/F

Soooo, I decided to try to reduce the A/F by *adding* 10% to the low ve cols...which DID lower my AF ratio, but also made my car smoke a little at idle.

So I undid those changes, and went to the old 70/80/90 scaling, and the idle did get better...but the A/F is now at 20:1.

Also, the car seems to not like any extra timing in the idle cells.

Only other changes to idle are the standard:
Idle Limiters --> IAC Park Position: Raise all points from 40C and up to 21
Idle Limiters --> Idle Air In Gear: All points 60C and up to 8.6

Any help here?

Thanks,
Aaron

WS6FirebirdTA00

iTrader: (33)

dont worry about what the writeup says, just go log with the WB on the car and do what it tells you to. if its 18:1 at idle that is WAY WAY too lean, you want to go for stoich at 14.63:1 for all idle/part throttle and set enrichment up for WOT around 13.0

soundengineer

iTrader: (16)

WOT 12.5~12.8
Idle and PArt throttle 14.63

remember..with a cam you car likely Idles and drives in the same MAP areas....so it would make no sense to try to get AFR for idle and part throttle to be diferent #'s

sgarnett

iTrader: (1)

Don't forget, even if the engine is warm it takes a while after startup to purge all the air from the exhaust system so you are getting a stock reading. If you still have the AIR pump, that will dump extra air into the exhaust after startup and cause false lean readings. It may also be going lean from deceleration fuel cutoff.

In other words, under what conditions are you seeing the lean idle?

soslo

iTrader: (12)

I am seeing the lean idle when I am sitting in the parking lot at work idling the car. I've also seen this same high A/F value duing driving over the past day (last night/today).

Is the main VE table where I should be tuning for idle A/F? Or is there a better place?

To get my A/F down to 14.6 I'd have to scale my low VE cols by approx 120% from stock...which seems opposite of what I have read everywhere...

WS6FirebirdTA00

iTrader: (33)

yes the main ve, but if the maf is not disabled and retuned once the ve is done it will screw with things

soslo

iTrader: (12)

ahh, I need to not use the MAF anymore?

WS6FirebirdTA00

iTrader: (33)

u can still use it but while you are tuning if the MAF is enabled the VE and maf settings will fight each other

WS6FirebirdTA00

iTrader: (33)

once you get done tuning the VE you can then calibrate the maf so you can use it

soslo

iTrader: (12)

Is there a doc somewhere explaining this tuning approach? I've basically been using the nogo method...

WS6FirebirdTA00

iTrader: (33)

yep they are all over, what software do you have?

soslo

iTrader: (12)

I have LS1Edit. Thanks for the help everyone.

BTW - I have the car idling quite well. No hunting. Pretty smooth. And the A/F at cruise/slight throttle is typically in the low 15s.