Z31 Tune Help

J & J Speed Shop · Post by **J & J Speed Shop** » Sun Jul 12, 2009 4:37 am

Vehicle:

1986 Nissan 300zx, with the VG30ET turbo swap, larger turbo, cams, Ford Cobra MAF / AFM , and Mercedes 420cc injectors

Having a bit of trouble tuning this car. Read up on setting the Injector Multiplier K value. I set the O2 feedback temp to max, set the raw fuel table to 0, and unplug the factory O2 sensor. With the wideband I set the K value to 375 and get around a perfect 14.7 average idle. However this makes the car run very rich everywhere else (cruise and WOT)

With a K value of 300 the car idles very lean 18-19.0 AF, but off idle the rest is near perfect at cruise and wide open throttle 11.5 AF at max RPM & load

The thing I am unsure of is how to adjust the fuel, like which table to use (Raw value, filtered, HEX, target AFR, Target lambda, Target pulsewidth), also kind of unsure why the idle section numbers (with the flags tags) are in the almost 200's vs. the rest of the table which looks like a std. VE table

Is there something I am missing to richen up the idle a little bit besides the main RAW fueling table?

TM_S13 · Post by **TM_S13** » Sun Jul 12, 2009 8:17 pm

it seems it now need the map iftself to be changed where it's needed...
don't know for sure though... still a rookie

Matt · Post by **Matt** » Mon Jul 13, 2009 1:58 am

TTPMin been adjusted to allow smaller pulsewidth?

If so then get your K so the map is around 14.7:1 and then afterwards use your 'Injection latency' to adjust idle pulsewidth so it isnt so lean

We typically use Filtered view in the fuel map and then use the AFR tracer to monitor the wideband feedback whilst tuning

J & J Speed Shop · Post by **J & J Speed Shop** » Mon Jul 13, 2009 3:37 am

Matt wrote:TTPMin been adjusted to allow smaller pulsewidth?

If so then get your K so the map is around 14.7:1 and then afterwards use your 'Injection latency' to adjust idle pulsewidth so it isnt so lean

We typically use Filtered view in the fuel map and then use the AFR tracer to monitor the wideband feedback whilst tuning

TTPMin has not been adjusted. How do I go about adjusting it?

When you say adjust the K so the map is around 14.7, are you talking idle or part throttle low load. I am pretty sure I have the Injection Latency at 750 us for the Mercedes injectors.

Also do you do all your tuning with the stock O2 disconnected and the O2 feedback temp set to MAX so the computer isn't adjusting when you are trying to tune?

What is the typical setting for the 420cc injectors and Ford Cobra MAF? Seems it would be easier to set the K value low at 300 and richen up the idle area of the map instead of setting the K value to 375 and trying to lean out the MAP almost everywhere except idle.

Matt · Post by **Matt** » Mon Jul 13, 2009 2:20 pm

TTP min should be adjusted for you if using the Resize injector window

Part to full throttle should be around 14.7:1

Do this with O2 sensor temp increased - that should be good enough

Have you had a look through the tuning documentation and mapping manuals?

Not sure on that setup, since I use Z32 and 444CC on my setup