andy-gts

I was trying to do the wot tuning with the sharktuner and it wouldn't tune the cell and then I noticed the tuner didn't recognize the wot position nor that I was out of park.
I then did a data log at foot to the floor and the AFR was registering 15 and 16...there for is my wot switch shot.?
John Speake are you out there?

Bill Ball

Andy:

John is probably sleeping right now. Sharktuner shows you the throttle switch status right on the system monitor page or you can select throttle position for logging. If you don't see "3" in the throttle position log when you floor the gas pedal, you've got your answer. Be sure all slack is out of your both halves of the throttle cable before you declare the switch defective.

IcemanG17

Bingo
Chances are a throttle cable is too slack causing the WOT to not engage...which leaves the "cruise" map enabled which keeps the O2 in the loop...so it will try to reach Stoich or 14.7 AFR...... vs around 12.5 for the normal WOT settings...

Louie928

The WOT switch closes at around 70% throttle. I doubt slack throttle cable would cause that much loss of throttle movement. Chances are that it is the throttle switch itself. Like Bill mentioned, the ST monitor page shows the throttle position switch state. It shows the position with the ignition on, but the engine does not have to be running. The throttle switch operation is something to check before you start tuning. I believe the LH will go to open loop at RPMs above around 3700 regardless of throttle position. The WOT switch does enable the WOT enrichment map.

GregBBRD

Actually, the slack in the cable is very common. We see cars, all the time, that don't hit the WOT switch that are cured when we adjust the cable....we refer to it as "the 928 performance secret". I've also found that 70% is a "dream".....it is usually much higher (switch comes in later).

Bill Ball

Yes, even though the switch is supposed to engage at 70% throttle, it's often more like 90-95%. That may be a sign of a partially defective switch, but, as Greg indicated, making sure the cable is snug will get these "90%'ers" to work when they didn't before. So, it's worth checking. It would be better if it worked at 70% but I'm rarely between 70% and WOT.

John Speake

Now you've woken me up :-)

Your question has been well answered...... although if you test a new throttle switch it does in fact hit WOT at 66 degrees from the closed postion, it appears that on the S4 and later that the throttle linkages either change the rotation ratio and/or there is also lots of posibilities of lost motion in the whole linkage system.

The loss of WOT switch affects igntion as well as fuellling of course. But on the igntion side it seems that actually disconnecting the WOT switch from the EZK is a better choice as then you can remap the igntion with both load and RPM, rather than just RPM on the stock WOT map.

The ST will not autotune the LH WOT values. But remember that all the high load/rpm cellls are on the base map. You need the WOT switch operational on the LH to be able to Autotune those cells to a richer A/F ratio at the highest loads. Even though it goes open loop, and there is transient enrichment, you need the WOT signal to be able to set the required open loop A/F.

Bill Ball

So, if the WOT switch is truly broken, he could just tune WOT in the base map. That's the way Louie has done it, IIRC. Goose those cells in the base map that are active under various WOT conditions until you get the desired rich mixture there, and tune the ignition base map as you mentioned. If base map tuning works so well for WOT, it leaves me wondering why the WOT maps are there.

Bill Ball

It's odd if this is the case, as the throttle plate is close to fully open if the cables are snug and the pedal is mashed, so it's not as if the throttle is barely making it past 2/3rds.

worf928

The trick with that method is that you also need to turn off the O2 adaptation. Else, the adaptation may end up leaning out the cells that you've tuned to the rich side.

Jim Morton

When considering these things, one should also consider the differences, cruise / WOT on the ignition maps... it's all part of the same combustion.

John Speake

You need the WOT switch working on the LH for the ST to tune high load cells to the "WOT ttarget A/F ratio" in Autotune. These will usually be a fatter A/F ratio than the rest of the map, which for most cars is set for 14.7:1 for the O2 loop.

AFAIK Louie has only ever disconnected the WOT switch feed to the EZK.

andy-gts

thanks for all your great insight!!!
this helps tremendoulsly and I hope this fixes the problem...so I can get back to tuning the car with the cams and sc combo.
thanks again
andy

Bill Ball

I misunderstood that the selection to disable O2 adaptation was temporary during Autotuning. I didn't know that would go into the code. I only find this described briefly in the PEM manual, of which I have draft 9.

Bill Ball

OK, thanks for clarifying.