oups59

Spring is now arrived in Montreal and it is time to play with my SharkTuner.

I did a first test yesterday - just the O2 loop check - and I already have some questions

Only modifications : x-pipe, no cats, GT mid-mufflers.

First, it looks like the car is running a bit rich. An autotune should resolve that issue.

RPM - A/F ratio - Throttle pos - O2 sensor adj [%]

739 13,34 1 0
728 13,21 1 -0,1
729 13,36 1 -0,3
747 13,22 1 -0,5
775 13,22 1 -0,7
797 13,15 1 -0,8
821 13,2 1 -1
838 13,31 1 -1,2
829 13,35 1 -1,4
827 13,49 1 -1,6
813 13,53 1 -1,8
803 13,67 1 -2
794 13,79 1 -2,2
792 13,77 1 -2,4

2376 13,95 2 10,3
2421 13,52 2 4,4
2462 13,66 2 4
2520 13,69 2 3,6
2576 13,65 2 3,3
2616 13,74 2 2,9
2648 13,57 2 2,5
2713 13,57 2 1,7
2744 13,38 2 1,4
2780 13,36 2 1
2828 13,47 2 0,6
2853 13,48 2 0,3
2881 13,38 2 -0,1
2929 13,45 2 -0,4
2959 13,34 2 -0,8



And then, very lean. This was at idle - RPM is high but settle down at after a few seconds.

900 13,89 1 17,4
907 13,98 1 10,6
911 13,9 1 10,8
912 18,99 1 11
913 18,99 1 11,2
915 18,99 1 11,4
925 18,99 1 11,6
931 18,99 1 11,8
930 18,99 1 12
931 18,99 1 12,2
935 18,99 1 12,4
941 18,99 1 12,6
940 18,99 1 12,9

I have the same pattern cruising:

3021 18,99 2 19,2
3064 18,99 2 19,5
3115 18,99 2 20
3175 18,99 2 20


I am a bit confused. I need to re-read the ST2 manual but having your inputs will be nice

Speedtoys

Are your engine management electronics in as-new condition, and intake system well sealed?

dprantl

Where is your wbO2 mounted? Are you using an nbO2 in addition to the wideband, or are you using emulation? Did you calibrate the wbO2 sensor in free air before installation?

Dan
'91 928GT S/C 475hp/460lb.ft

oups59

Free air calibration done last week. the LC-1 was installed last year.

The WB is mounted in the second bung (driver side) on the x-pipe. The NB is mounted in the other. I disconnected the NB for ST tuning.

oups59

Intake refresh done 4-5 years ago.

What do you include in engine management electronics ?

Speedtoys

All sensors, ground points..injectors..

oups59

I cleaned all ground points last year.

Sensors - Temp II was changed 2-3 years ago . I will need to verify for the others.

Injectors - original (I am looking to upgrade them to 24 lbs)

dprantl

I'm not understanding your O2 loop check if you disconnected the nbO2 sensor? Anyway, need more info. The first set of idle data, is that when the car is warming up, since it is so different from the second set of idle data? How old is your MAF? As they age, they read lean.

Dan
'91 928GT S/C 475hp/460lb.ft

oups59

I need the NB for the loop check ??? I always believed that I can do it with the WB...

First set = normal engine temp (before test drive)
second set = normal engine temp (after test drive)

MAF age = rebuilt 5 years ago

Hilton

Luc,

Unless you've wired the narrowband output from your wideband O2 into the LH harness as well as the ST2, its not giving any signal to the ecu.

Also, "Autotune" in the ST2 software is not intended for tuning - its intended for creating a base map for a new non-stock engine, which can then be tuned later using the Sharkplotter or by manually changing cells while tuning/monitoring AFR's.

You should also be disabling the O2 loop (and resetting the O2 adjust) and doing any logging/tuning in open-loop mode ("non-cat" mode and map).

You should read the manuals for both ST2 and Sharkplotter before doing anything more - then check your wiring, and use the ST2 software to make a "new" map (it can create a new stock map for S4 - to use as a baseline for changes). The manuals explain how to disable the O2 loop etc. in good detail.

Before making any changes, I recommend verifying your setup is correct, then just driving around for a bit with the ST2 data logging, so you have enough data to have a good play around with the Sharkplotter user interface. Once you've got a good idea of how the software works, and how your car is performing, then think about making changes.

Bertrand Daoust

Yes, spring is finally here... About time!

Luc, with all the help here, I'm sure you will get through it quite easily.
Sorry but I can't help you at all here... I don't understand a single word that you guys are saying!

I'll need a crash course on this at SITM...
I'll pay the beer!
Well, not sure if it's a good idea for me to try to understand things like that after a few beers...

oups59

If I don't have cats, should the NB wire (blue wire on my LC-1) be connected to ground (as in John`s diagram) ? This is how it is connected now.

For my first logging, I used the 98 octane cat (obey the coding plug). You suggest I switch to 98 octane no-cats and then do some logging ?

Thanks for your help

oups59

Just keeping the most important

Hilton

If running without the NB signal to the ecu, then the harness pin for the NB connector should be bridged to ground (non-cat 928's came with a small sureseal bridge plugged into that connector). If you look at the wiring diagram, it shows the bridge on the o2 connector.

As far as your coding plug setting - I'm not sure what the effect of unplugging the O2 loop is on a cat-coded car.

In the ST2 software, I'd just force non-cat mode, make sure the CO pot setting is set in the user interface (as you don't have one), and then tune against the non-cat maps. You can copy the map on top of the catalytic map once you're done with tuning, and plug in the narrow band O2 sensor.

(I don't have my ST2 stuff in front of me, or have XP installed on a laptop currently - so setting names might be a little off ).

oups59

Sorry, the NB (blue wire) is not grounded. I was looking at the heater ground wire (also blue). I am using the NB. I installed it to match the coding plug.