This is for the 747, does AE clip @ 25% or is there a slope adder or other calculation. Or is the ECM just supposed to catch up by then on fuel (ie" over 25% delta tps).

 

The max delta is 25%, that is correct. Anything greater is set to 25%. There is also the delta MAP AE contribution. With large TPS deltas typically come a good amount of delta MAP. So they go hand-in-hand.

Interestingly enough the '8746 TBI ECM only goes to 12.5% TPS delta. Lighter vehicle, less demand for AE.

It has been known to use a large value for the last table entry. And, can lengthen the AE duration with the AE filter coeficient tables (TPS & MAP).

 

AE based on load takes over from there.
On some of the codes where they have more steps, it's almost too much to dither, and make sense of, the Load vs TPS AE.

So far, it seems to work out fine.

 

8746 is used in the 89 and 90 Caprices (which are obviously heavy) and I just checked my $62 in TunerCat - same deal, 12.5 max. Maybe it's just an issue with conserving memory on those tiny 4k EPROMs.

 

I'm having some succsess with runing a big map AE, like 1.5x bigger than my tps table. Its too bad though, I think a 100% tps table would be good, Or maybe that would cause problems with too much fuel.

 

I dunno.
On the Gn code it goes to 100%, and noone seems to even bother tuning with it, other then me, and I probably could get by with just the LV8 AE.

Might try adding a lil in the VE table in like the 70-80 K/Pa range.

Might look and see what the max asyn pulse lenght is.

 

The reason I posted this topic, is cause when I floor it from under say 1200rpm it falls flat on its face after I installed the 454 tbi, but If only half throttle is applied its fine. Above 1500rpm no problem. And at the slow reading rate I get with winaldl scanner its hard to fix the problem.

 

Just as an alternative thought.
If things were perfect with the smaller throttle body.
And there is a 300 RPM range of where you go from works to doesn't work, you might have been just border line on the converter, and now need a slightly looser one. Depending on who does it, there's alot of room in what can be done with a converter, with stall vs flash speed.

 

This winter I actually was thinking of going with a brand name converter, I was looking at the hughes 3500, or the B&M 3200. Should be a nice mod as my current one is still 12", and these ones are both 10".

As far as fuel goes I flatened out my ve table from 70 Kpa higher at every rpm row. Now Its a lot better. Seems to be that my vac fuel regulator was making me go rich with the intial drop in vacumm.

 

The vacuum referenced regulator may be part of the problem. There is a lag between the vacuum changing and the fuel pressure changing in response. Another problem is that the ECM should be changing the BPC in response to the changing fuel pressure. Else the VE table gets screwy. Even if you do change the BPC in the ECM (via a vacuum referenced lookup table) this doesn't correct the AE PW. The volume of AE is not affected by the BPC, only injector flow. So changing the fuel pressure is changing the volume of AE.

If you'd like to try changing the delta TPS% AE table to double the range (halve the resolution) change this:

Go to location $77B in the bin, should be $48, change it to $01.

Now the delta TPS% table goes from 0 to 50%, so move the original values down in the table and add larger values from the midpoint (now 25% delta) up.

Also check location $006, bit 7 to be set (a 1). It should already be but you never know.

LD006: FCB $C0 ; Opt Word, 1100 0000
;
; b7 = 1 = select filtered tps option for accel enrich

RBob.

 

And if it is for a 1 ton truck?

ECM/PCM: ECM #01227747
Used in trucks: GMC

C3500,2WD,1 TON C3500,2WD,1 TON G30 VAN,2WD,1 TON
G35 VAN,2WD,1 TON K3500,4WD,1 TON K3500,4WD,1 TON
R20,2WD,3/4 TON R2500,2WD,3/4 TON

RBob.

 

RBob,

What will changing my tps from 0-25%, to 0-50% do for the resolution between table values. Does the ECM just use a straight line slope of the upper and lower values when a value is between two table values.

Or what a second.......from your papers, its just a first lag filter right.

 

It is a straight line between the table rows. A sixteen point linear interpolation. There will be some loss of fine control. This is one of those things that you need to try it to find out if it matters.

Of course with the AE code in EPROM, and lots of EGR table space, the AE table can be expanded.

RBob.

 

16 point is better than I thought it would be.

Rbob do you have a copy of your fueling paper? as DIYEFI is still own I think.