7747 choke functions...
03-29-2003, 07:00 PM
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Car: Bee-Bowdy
Engine: blowd tree-fity
Transmission: sebin hunnerd
Axle/Gears: fo-tins
7747 choke functions...
I have everything tuned in so it's driveable for the most part. The only issue I have left is cold start.
I've been thru a bunch of hacks multiple times, and I see that there are ALOT of things that all work together to form the final choke function.
I was hoping someone could shed some light on this as I'm having trouble putting it all together.
I got all this stuff from the ARJU hack:
I've been thru a bunch of hacks multiple times, and I see that there are ALOT of things that all work together to form the final choke function.
I was hoping someone could shed some light on this as I'm having trouble putting it all together.
I got all this stuff from the ARJU hack:
Code:
;---------------------------------------------
; CHOKE FUNCTIONS
;
;---------------------------------------------
LD2D2 FCB 8 ; 1.8 SEC'S, COLD AFR (CHOKE) TIME OUT
LD2D3 FCB 10 ; 2 SEC'S, COOL TIME OUT (CHOKE)
LD2D4 FCB 10 ; 2 SEC'S, HOT TIME OUT DECAY
LD2D5 FCB 64 ; 80c THRESH FOR TIME OUT DECAY
;---------------------------------------------
;---------------------------------------------
; TIME OUT AFR vs COOLANT
;---------------------------------------------
ORG $0427 ; AFR DEG c COOL
;---------------------------------
LD427 FCB 59 ; 5.9 COLD
LD428 FCB 45 ; 4.5 -7.0
LD429 FCB 37 ; 3.7 6.5
LD42A FCB 32 ; 3.2 16.0
LD42B FCB 27 ; 2.7 24.0
LD42C FCB 27 ; 2.7 31.0
LD42D FCB 27 ; 2.7 37.3
LD42E FCB 27 ; 2.7 43.7
LD42F FCB 27 ; 2.7 49.7
LD430 FCB 27 ; 2.7 56.5
LD431 FCB 27 ; 2.7 63.5
LD432 FCB 27 ; 2.7 71.5
LD433 FCB 22 ; 2.2 80.5
LD434 FCB 22 ; 2.2 92.0
LD435 FCB 22 ; 2.2 108.5
LD436 FCB 22 ; 2.2 138.5
LD437 FCB 22 ; 2.2 HOT
;---------------------------------------------
;---------------------------------------------
; TIME OUT DECAY MULT vs COOL
; TABLE = FACTOR * 256
;---------------------------------------------
ORG $0438 ; MULT Deg c COOL
;---------------------------------------------
LD438 FCB 243 ; 0.949 COLD
LD439 FCB 248 ; 0.969 -7.0
LD43A FCB 251 ; 0.980 6.5
LD43B FCB 251 ; 0.980 16.0
LD43C FCB 243 ; 0.949 24.0
LD43D FCB 243 ; 0.949 31.0
LD43E FCB 251 ; 0.980 37.3
LD43F FCB 251 ; 0.980 43.7
LD440 FCB 251 ; 0.980 49.7
LD441 FCB 251 ; 0.980 56.5
LD442 FCB 251 ; 0.980 63.5
LD443 FCB 251 ; 0.980 71.5
LD444 FCB 251 ; 0.980 80.5
LD445 FCB 243 ; 0.949 92.0
LD446 FCB 243 ; 0.949 108.5
LD447 FCB 243 ; 0.949 138.5
LD448 FCB 243 ; 0.949 HOT
;---------------------------------------------
LD2FE FCB 27 ; 2.7:1 AFR TIME OUT FOR COLD PK to DRIVE
LD2FF FCB 50 ; 10 sec DELAY FOR COLD AFR PK to DRV CHANGE Last edited by V8Astro Captain; 03-29-2003 at 07:04 PM.
03-29-2003, 07:26 PM
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Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Keep your current chip intact, so you have a know way of starting the engine.
For doing this you might install one range hotter of plug, at least till you get the hang of what you're doing.
First Make Absolutely sure your Min Idle speed and IAC count when warm is 100% the way you want them.
I haven't looked at the 747 lately so there may be some differences from what I mention to what you see.
Then make sure you Max IAC is higher then any other entries.
The Park posistions might need adjusting, try higher first. Too small and the motor goes way rich at first start. Just change the step counts by 2. Big changes can get you lost quickly.
Look at the TPS crank enleanment and note how your clear flood mode works.
Then trying LEANING the crank fuel stuff SLIGHTLY and see how it starts, it should be obvious when you go in the wrong direction.
It's easy to go too rich during crank and foul the plugs. Gotta go slow take notes, and be sure it's really as cold as possible just having heat in the intake manifold can mess up the procedure.
really shouldn't have to worry about the spark and fuel decay rates.
The park posistions and IAC posistions do ALOT.
For doing this you might install one range hotter of plug, at least till you get the hang of what you're doing.
First Make Absolutely sure your Min Idle speed and IAC count when warm is 100% the way you want them.
I haven't looked at the 747 lately so there may be some differences from what I mention to what you see.
Then make sure you Max IAC is higher then any other entries.
The Park posistions might need adjusting, try higher first. Too small and the motor goes way rich at first start. Just change the step counts by 2. Big changes can get you lost quickly.
Look at the TPS crank enleanment and note how your clear flood mode works.
Then trying LEANING the crank fuel stuff SLIGHTLY and see how it starts, it should be obvious when you go in the wrong direction.
It's easy to go too rich during crank and foul the plugs. Gotta go slow take notes, and be sure it's really as cold as possible just having heat in the intake manifold can mess up the procedure.
really shouldn't have to worry about the spark and fuel decay rates.
The park posistions and IAC posistions do ALOT.
03-30-2003, 08:09 PM
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Car: Bee-Bowdy
Engine: blowd tree-fity
Transmission: sebin hunnerd
Axle/Gears: fo-tins
Yep, I didn't change much of the choke functions, but I set the IAC park to 100 and max retract to 140. Now it starts smooth with almost no knock AND it idles real high like I want it to.
Before I had the max retract AND park set to 100. I guess that was just too low. Like you said, max IAC needs to be higher than the other entries.
Before I had the max retract AND park set to 100. I guess that was just too low. Like you said, max IAC needs to be higher than the other entries.
03-31-2003, 02:16 AM
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Car: 91 Red Sled
Axle/Gears: 10bolt Richmond 3.73 Torsen
Bingo! IAC is evil, just remember that 
. I had the EXACT problem yesterday when the weather got cold again and the car was running really rich fouling the plugs and not restarting right away. Even got as bad as having to require my TPS position to be 50% for a 20:1 "clear flood afr". Had to use that a couple times. Anyways, turns out I wasn't running enough timing and too much fuel but also the IAC park position was at 50. I can't remember why I moved it there but I did, anyways, try setting it to 0 and starting. It most likely won't. Put the IAC back to 160 and she fires right up. I still had to lean it out a little but that was also because of the vac.rafpr. Let's just say that I have a VERY strong feeling that the Holley regulator isn't good for less than 14psi of fuel pressure with the walbro 255lph fuel pump. If it is, I can't figure it out and I thought all I had to do was back off the spring 
.
Oh yeah, and those AFR's are added to another table. Should be a couple or a few, can't remember but in the 8746 they're only a page apart. I believe the other adder table has to do with either baro or just engine map. If you've got the time check it out. It's pretty cool charting out the tables in excel to make sence of it all.
. I had the EXACT problem yesterday when the weather got cold again and the car was running really rich fouling the plugs and not restarting right away. Even got as bad as having to require my TPS position to be 50% for a 20:1 "clear flood afr". Had to use that a couple times. Anyways, turns out I wasn't running enough timing and too much fuel but also the IAC park position was at 50. I can't remember why I moved it there but I did, anyways, try setting it to 0 and starting. It most likely won't. Put the IAC back to 160 and she fires right up. I still had to lean it out a little but that was also because of the vac.rafpr. Let's just say that I have a VERY strong feeling that the Holley regulator isn't good for less than 14psi of fuel pressure with the walbro 255lph fuel pump. If it is, I can't figure it out and I thought all I had to do was back off the spring .Oh yeah, and those AFR's are added to another table. Should be a couple or a few, can't remember but in the 8746 they're only a page apart. I believe the other adder table has to do with either baro or just engine map. If you've got the time check it out. It's pretty cool charting out the tables in excel to make sence of it all.
03-31-2003, 01:20 PM
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Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Originally posted by JPrevost
Bingo! IAC is evil, just remember that
I believe the other adder table has to do with either baro or just engine map. If you've got the time check it out.
Bingo! IAC is evil, just remember that
I believe the other adder table has to do with either baro or just engine map. If you've got the time check it out.
It's Baro and only makes a tiny change. It accounts for the change in exhuast back pressure due to atmospheric conditions.
If you park in a heated garage, and then pull out into freezing conditions you can notice a change after it does a reset, but it's not a big deal on any one given day, when driving in normal conditions.
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