Let me see if I have this correct?? (8D on a 727) (I have relabled some of my XDF items. sorry)

The cranking fuel comes from the "Crank Pulse Width Vs. Temp" that's the starting point. The "PW Mult. Vs. Ref Pulses 1-24" is multiplied against the PW VS Temp?

Fuel is then delivered to the injectors after the "Fuel Delivery Delay Vs. MAT" has elapsed? What is the unit measure of this delay? The Column Units is "DRP" does any one know what that is?

Q - So here's where I'm really fuzzy. I have an item labeld "Crank AFR Vs. Temp". Did I relable this item incorrectly? I'm guessing that it is reading off of the 400 rpm line in the lower VE table, but I can't tell when it gets involved in the whole start up equation. It definitely makes a difference in startup (I found out the hard way).

Also, since the Crank AFR Vs. Temp is a %AFR adjustment off the 400 rmp line (guessing)... then when it first starts cranking the MAP values are high (mine is at 96 due to my altitude)... but my engine idles around MAP of 35. So can I find out which VE cell my startup routine is taking its values from??

Thanks in advance.

 

Could you add the addreses into your descriptions.
that way I can look into what I have later at home.
I don't recall "Crank AFR" anything off the top of my head. IIRC just the crank PW table values and the temp compensation of them are all that is active but have to check.

 

Sorry, I'll remember to include the addresses from now on. I went nuts renaming and rearanging the xdf.

I greatly appreciate your assistance on this subject. It is obvious that I really haven't got a clue what the logic is on this subject.

Crank PW VS Temp ($03AF)
PW Mult. Vs. Ref Pulses 1-24 ($03C7)
Fuel Delivery Delay Vs. MAT ($039C)
Crank AFR Vs. Temp (known as Enrich startup Vs Temp) ($0431)

 

Can someone please answer this question. and explain what the delay does.
Fuel is then delivered to the injectors after the "Fuel Delivery Delay Vs. MAT" has elapsed? What is the unit measure of this delay? The Column Units is "DRP" does any one know what that is?

 

- Base PW for cranking.
- modifier to crank PW (i think $80 = 100)
- DRP's are distributor reference pulses and delays injecting crank fuel - it should be for trying to start with fuel vapors, building fuel pressure and oil pressure.
- startup is AFTER cranking (i.e. RPMs > 400), and is used to keep the burned air/fuel in line due to fuel dropout and wall wetting for a cold engine and combustion chamber. 7.3:1 is doubling the fuel. It decays out over a few seconds ~about 30 seconds is normal.

 

Thanks

 

How does the fuel delivery delay vs. MAT work?

Let's use a scenario of 104*C and AXXD stock crank fuel delivery delay table, located at 039C, which calls for 8 DRP's of delay.

Now, also using AXXD stock values, you have a crank pulse multiplier table at 03C7 which looks like this:

16: 0.25
15: 0.25
14: 0.25
13: 0.25
12: 0.25
11: 0.25
10: 0.25
9: 0.25
8: 0.25
7: 0.25
6: 0.25
5: 0.25
4: 0.25
3: 0.25
2: 1.00
1: 1.00

The question:

After the 8 DRP's of delay, do you start at the 9th DRP value in the crank pulse multiplier table, or do you start at the 1st DRP value?

Or, stated differently, is the logic such that the first 8 DRP's are ignored as if they didn't exist, and the 9th DRP acts as if it were the 1st DRP? Or the first 8 DRP's are counted, but the inj PW's are just zero'd out due to the delay table?

 

And as a further followup, here is a comparison of the crank pulse multiplier tables for AUJP, AXXD (305-5spd F-bod) and AXCN (350-6spd-vette).

The different strategies really surprise me, especially the difference between AUJP and AXCN given that the engines are identical.

 

AUJP is automatic,
Could be converter and pump loading need additional fuel when cranking.