TPS wont go above 3.86

[bruce]

For another perspective on TPS fueling here's the PE TPS fuel table from both the AXCA and BBKJ stock GM images for reference: If you use a 5volt reference voltage for TPS, you can see that at 75% TPS which is anything over 3.75V your getting all the TPS releated fuel you can aka 19%. So your TPS voltage needed for max fuel input will still depend on wether or not your specific chip vendor modifies this table and wether or not 3.xx volts is the magic number for achieving maximum TPS (strictly % position related) fuel input to the PE fueling equation....period, end of story.

Also as Bruce kindly points out, your idle to WOT TPS voltage range also effects AE fueling via delta TPS so having a WOT setting of 3.xx compared to 4.xx will still effect fueling in other areas of the code as the throttle is moved.

0% PE Fuel Trim vs TPS (0% - 200%) 0%tps
0% PE Fuel Trim vs TPS (0% - 200%) 13%tps
5% PE Fuel Trim vs TPS (0% - 200%) 25%tps
13% PE Fuel Trim vs TPS (0% - 200%) 38%tps
16% PE Fuel Trim vs TPS (0% - 200%) 50%tps
17% PE Fuel Trim vs TPS (0% - 200%) 63%tps
19% PE Fuel Trim vs TPS (0% - 200%) 75%tps
19% PE Fuel Trim vs TPS (0% - 200%) 88%tps
19% PE Fuel Trim vs TPS (0% - 200%) 100%tps

HTH

Thanks for mentioning this.
As I mentioned the log I posted was from modified code (It's what I've been working on for the last few years), so I missed mentioning that.

Using the table that you've shown here, is what helps compensate for some of the MAF's short comings. But, going *there* would be hijacking this thread.

 

[Ormand]

If the ECM looks for 3.75 volts as wide open throttle, and you have a TPS which will only go to 3.8, or so, then there is very little margin there. The engine will not reach full PE until the throttle is nailed to the floor. Don't know about you, but I would prefer to have the PE begin when there is still some gap between the pedal and the carpet. Seems to affect throttle "feel".
I've been following the Buick boards for years, and have yet to see superman make one single post. My guess would be that he doen't need a Buick to fly.
But Bruce certainly knows all the nitty gritty details of the ECM.

 

[ijames]

There are really two issues here. One is that there are several parameter thresholds to get into PE mode, one of which is the tps, and that threshold is not a single tps value, but taken from a table indexed by rpm. Those thresholds are all well below 3.86 V, so in that sense 3.86 V is "enough". However, once in PE mode there are again a few parameters that determine how much extra fuel is injected, and one of those is again the tps value as shown in the table Mark posted. So if the max tps is too low you can be in PE mode but still not be getting as much fuel as you would if the tps were able to go higher. Again, as Mark showed, in the stock chips 75% tps gets you all the additional fueling from the tps, but I have seen at least one aftermarket chip where that table was changed so that you needed 88 or 100% tps to get the maximum fuel so there really isn't a simple blanket "xx volts is enough" answer even to make sure the maximum amount of fuel is added. When you also include the A/C cutoff threshold (which I've never seen anyone else but me lower and I don't understand why since heat is your enemy under boost ), the fact that 75% tps gives no margin if anything goes slightly wrong, and the fact that after helping about a half dozen new-to-TR drivers learn to tune and seeing every one of them start out thinking they were at WOT when the scan tool showed they were really at about 80-90% (big key is moving the seat forward a couple of clicks; some also need to rearrange their carpet), I think 4.3-4.5 volts is a much better WOT setting.

 

[bruce]

If we want to really *get* into it, there's also, K3, and K4 variables that can be altered, which I've never seen anyone but me use.

And if we're going for *all* of it, then yes, there's an addition requirement for PE, a min airflow setting for enabling PE mode. And while I'm sure others have messed with it, I haven't seen anyone...

Yes there are others (or at least someone else) that have lowered the A/C disable setting.

 

[bruce]

For the full, and complete answer,

http://www.t6p.com/forums/showthread.php?p=56816#post56816