Whats the best way to work out crank PW ?

[Holden202T]

as per the title ... im battling with crank PW numbers ..... so for starters im using a 3.8 or 5ltr tune as a base, then i offset the numbers to suit the difference in capacity to suit my 3.4ltr (holden 6)

then i have to offset them to suit the change from stock injectors to 80lb injectors ... so this is approx 1/4 the injrate numbers for petrol and 2.3 times that number for methanol

problem im having is when starting the car, hot or cold it just about floods on the first fire, then from there its hard to get it started till the flood clears!

does anyone have a proven theory on the best way to work out what these numbers should be or should i just start lean and slowly richen it up a few percent at a time till it starts ok ?

is it worth looking at wideband numbers when cranking .... im not really sure what to expect to see there....

[delcowizzid]

i halved them to suit my injector size for a start remember theres more than one start bpw table normally dunno about 12p but most other codes have 2. once its halved or whatever to suit the injectors plug the wideband into direct battery power so it doesnt shut off on crank and can warm up before starting the car.then you dont have many cold starts before its too warm to do that area anymore makes it hard will take a few goes.you could also work out what your idle pulsewidth is oin the logs and go off them as a rough guide

[Holden202T]

12p has initial crank pw and secondary crank .... not sure what the timings are from when it changes from one to the other though.

i have changed the numbers eg. -28 degrees from 16.2 to 12 and the rest the same percentage so i'll see how that goes with the wideband and go from there....

[Holden202T]

further investigation has shown some possible issues .....

found some good info on the injectors as far as minimum pw and voltage offsets and such so with that i've made some changes.

Minimum Crank BPW - was 4ms thats now 1.5ms
Minimum BPW for Sync Delivery - has been changed to 1.5ms
Minimum Asynchronous pulse width - this was .20 so i've changed it to .6 (to suit injector working parameters)

so i reckon the old 4ms minimum crank is whats causing it to flood when hot cause the 80 degree number is 2.44ms .... so thats nearly half what it would have been getting, so i'll just have to see what happens in the cold areas i guess.

[Holden202T]

Well for those that are interested this is the results so far.....

started with this for Initial Crank BPW

1.95 - 116 degC
1.95
1.95
2.44 - 80 DegC
2.44
2.93
3.42 - 44 DegC
3.91
5.86
8.79 - 8 DegC
11.72
13.67
16.60 - -28 DegC

tried it with this tonight....

1.95 - 116 DegC
1.95
1.95
2.44 - 80 DegC
2.44
2.93
3.42 - 44 DegC
3.91
4.88
6.35 - 8 DegC
7.81
9.77
11.23 - -28 DegC

So its still slightly flooding when cold, much more managable with a bit of throttle though, and when its up to 80-90 degrees its pretty much spot on doesn't seem to sound like its flooded at all on start.....

somethings still not right with the minimum BPW though as its going below the 1.5ms i set for it and its not going into async mode when i think it should be so i've emailed VL400 to see what the go is, this is causing some dodgy idle issues, but for the most part im heading in the right direction ... gonna put the WB back into the gemini tomorrow arvo and see what the numbers say and fine tune from there.

on a side note and another question i put to VL400 .... it appears that the initial crank bpw and second stage crank bpw tables are either labelled wrong or something like that ..... basically whatever the numbers are in each table for v1.03 they are the opposite in v1.04 ....

im not sure if this is a migrating cal issue or just the labels ass about in the XDF but we'll soon see i guess .... but if anyones playing with these tables be aware of it!

[VL400]

somethings still not right with the minimum BPW though as its going below the 1.5ms i set for it and its not going into async mode when i think it should be so i've emailed VL400 to see what the go is, this is causing some dodgy idle issues, but for the most part im heading in the right direction ... gonna put the WB back into the gemini tomorrow arvo and see what the numbers say and fine tune from there.

on a side note and another question i put to VL400 .... it appears that the initial crank bpw and second stage crank bpw tables are either labelled wrong or something like that ..... basically whatever the numbers are in each table for v1.03 they are the opposite in v1.04 ....

im not sure if this is a migrating cal issue or just the labels ass about in the XDF but we'll soon see i guess .... but if anyones playing with these tables be aware of it!

Sync and Async are for fuel pulses being in time with the ref pulse or out of sync with the ref pulse and being delivered every 12.5mS. Under normal conditions you will be using sync fuel, when you invoke AE or exit DFCO the ECM will command some extra fuel. This extra fuel is an async pulse delivered between normal sync pulses. You need to be looking at the single/double fire flag for idle fuel control when it goes below the min value. Have renamed the min BPW item item in the XDF for the next release to make it more meaningful "Run A/F Param - Minimum BPW for Sync double fire fuel delivery" and the notes "Changes to single fire mode when fuel PW goes below this value".

The tables being swapped was a labeling issue i found in versions before v104. The current state is now correct.