All numbers/values I'm using are examples.
Assuming i want a 12.5:1 AFR at WOT (say from 2800 to 6400 rpm)
I change the table "Enrich power change to AFR vs RPM" with values = -4.82
[Pe AFR = 14.7/(1 + %change vs. cool /100 + %change vs. rpm/100) ]
then with a WB i perform some WOT runs.
The WB show a costant 13.50 AFR. (much more lean than desired)
The first thing that comes to my mind is to modify the VE tables on the 90-100 map values on 2800-up rpm values.
What to do if the VE values are 95?
13.5/12.5 = 1.08
95 * 1.08 = 102.6 !!!
VE values over 100 are allowed???
-Beppe-

 

VE Values are maximum of 100%. Can not go over that. In this case you can set the injector constant as a smaller injector. That will cause all fueling to have a greater PW.

Another item, due to the engine displacement, have you patched the BIN for the PW fix? If not you really need to do that. Otherwise the PW goes flat and no more fuel can be added.

RBob.

 

This is not my situation...
...BTW Which patch are you speaking about
-Beppe-

 

Found it !
Thanks

 

Why would you be removing fuel (-4.82) from the PE table and trying to add it back using the VE table?
Your VE tables should be for overall operation at 14.7 when not in PE mode.

Then the PE table makes the correction for the 12.5 or whatever your going for at WOT.
If you change the -4.82 to a +4.82, the WB would go towards richer.

 

Whether it is commanding a richer or leaner AFR from stoich is dependent upon how the ECU/XDF/TDF file entry is created. Which is unfortunately a big gray area. It should be double checked from the data log's commanded AFR field. That will tell the tale.

RBob.

 

For what I learned in these years, the negative value DOES NOT remove fuel.
if you put the negative value I used only for the example (-4.82) in the formula above mentioned the commanded theoretical AFR is 12.5.
Yes, If you are modifying an existing positive (+) value of example 2.90 to (-4.82) you are removing fuel , because you are switching from 11.7 AFR that is richer than 12.5 AF
-Beppe-

 

RBob, I read the PW limit thread (about 10 times..) and it seems I have to implement it.
The reasons i think I have to implement it are:
1) I have large displacement engine and the bin has a Cylinder volume costant of 811.66 (396 c.i.)
2)I have the inj. costant larger than the real injector flow = 32 lb/h
(I have 30 injectors .-the fuel pressure is sligtly more than stock-).
BTW I haven't relocated the MAT that is in the plenum on my SR.
I really dont understand all about this Z69 thread.
I understand that the PW can stops to increase over a certain rpm especially on larger CI engines even increasing VE values. This is due to the logic of the PW calculation
I understand how to change the bin , even if I don't understand why it should be changed as proposed, because I don't know which constant/parameter will be changed swapping values on the hex editor.
Probably this hardcoded change, changes the logic of the PW calculation..
(all Hardcode changes that are not in parameter, constant, and tables in Tunerpro are a bit difficult to understand for me... ).
I need to be assured that the change I have to do is:
change DE F1 BD E4 24 FE 84 1C starting at 4C79-4C80 in ANHT
to:
FE 84 1C BD E4 24 DE F1

thanks.
-Beppe-

 

I would like to know also

 

...So, we need to put this thread UP ^^^ .

 

Uhh, have you tried the change? If it isn't correct you will know it upon starting up the engine. It is a major change in how the PW calculation is done.

OTOH, I did take a quick look at the address and values. At a quick look it does appear to be correct. If not, you'll be the first to know.

RBob.

 

I haven't tried yet, I'm fighting a bounching idle, so I have to try/test some changes I made in the idle VE rpm/map values.
...And If I correct understand, the Z69's "8D PW limit patch" seems alter the lower rpm VE values (even if i don't understand why...-I think it's a lower "resolution" due to the patch-).
-Beppe-

 

I put the 8D PW limit patch on my bin. NO side effects on part throttle driveability. I vemastered a datalog with the PW patch as the only modify .
All were just in the same spot as before.
I datalogged some 2 gear to 3rd gear WOT just to monitor the PW.
The "injection BPW " follow the target afr and it stay in the 8.xx range.
I was expecting that with the rpm increase the bpw increase also...
I'm wrong on expecting this?
The o2 values during the WOT are completely out...
When I stomp on it the O2 jumps to 950 then always with the right foot on the flor, it strats to reduce to 900 then 850 then 800...there is even a 288 value(!), then it climbs again to 800-850 mv , but never over 850.
The very big problem is that probably the real AFR is lean very lean.
What do you think?
Thanks
-Beppe-

 

Beppe,

Why not just add extra positive PE vs rpm enrichment (something like + 5 % = 11.5 or +11% = 11.0) to make your target AFR richer, since you seem to have about a 1.0 offset between the real AFR and target AFR.

 

I tought this also.
It's time to hook up my Zeitronix Zt-2 just to see REAL numbers.
What is shocking me is that I'm at 95 values on VE tables on high loads (90 to 100 Kpa) .
The 8D calibration call for correct VE values. If the values are near to be correct, the calculated target AFR on the table "Enrich power Change to AFR Vs. Rpm" should reflect the real AFR .
Now, when I'll have the opportunity to test the real AFR with my WB, and (as supposed) it will be lean, this means that I have to raise the VE to 100 or I have to raise the table "Enrich power Change to AFR Vs. Rpm" to theoretical 10.xx AFR, and doing this to reach a real 12.5x..AFR, is suggesting me that something in the equation is wrong. This put the question as in the #1 post message.
-Beppe-

 

One more thought: Is your fuel pump keeping up with the flow demands?

It sounds like a combination of reducing the injector constant, maybe increasing the cylinder displacement or increasing the VE or PE could get you where you want to be.

Something is introducing error, either extra air that is not accounted for properly or perhaps a fuel flow restriciton.

Of course, the WB/NB readings could be erroneous also if there is any air leaking into the exhaust.

I agree it would ne nice if the target AFR and actual AFR from the WB are in agreement as it would make things simpler for future tuning.

Good luck.

 

I used a gauge on the winshield to read fuel pressure , and even at WOT at +6000 rpm is steady at 47 psi.
OK, air leaking in the exhaust can be a problem... but also spark plugs are in the lean side...

P.S. an air leak in to the exhaust can be a problem even if it's PAST the oxigen sensor?...or I have to be worried only for leaks from heads to O2 sensor?

here the wot datalog : see the BpW and the strange O2 mV values.

 

IM A CARB GUY AND AFTER READING ALL THAT IM STAYIN A CARB GUY HAHAHA jk....

YOU GUYS ARE CHANGING A SCENERIO INSIDE A SYSTEM. GO OUTSIDE THE SYSTEM OF YOU CANT FIND THE RESULTS. TRY A LITTLE OCTANG BOOSTER OR EVEN LOWER GRADE GAS. JUST THE PROPETIES OF THE TIME THE FUEL BURNS DOWN THE CYLENDERS IS A HUGE HUGE FACTOR. ITS A CHEMICAL FACTOR... YOU MAY HAVE LEFT OVER GAS BECAUSE IT CANT BURN IT ALL NO MATTER HOW YOU PUT IT IN..???? AND YOU CAN ONLY CHANGE THAT ONE WAY. CHANGE THE FUEL ITSELF. GOODLUCK

 

Unburned fuel... you are make me thinking...
All these attempts (datalogs, theory, and chip mods..) are made after a spark plug change. I used the same spark plugs (the same heat range).
What I missed to check is the obvious thing. The gap
Only after your reply i'm remembering a set of the same plugs with a gap of .020" !! I usually gap them to .040".
What the theory says about a really,really small gapped plugs? They are maybe less efficient on burning the gas mixture??
-Beppe-

 

well if it aint it, thats what keeps this hobby a hobby hahahaha!