basics of tuning delco non $12p

[drift-it]

im most likely off in my thinking. but in first could the vac applied to the reg be different? because i've noticed on my boost gauge that theres less vac in 2nd compared to 1st at the same rpm range??? like in 1st there will be -10hg at say 2500. and in 2nd at 2500 theres -5hg...just a thought.

o and explaining to ya missus about E85. jsut tell her it helps with economy and makes the car run alot smoother. thats the story my missus gets

[sprattzvx]

hey there drift,
nah only see only see vac on light throttle. in this situation full boost here running off pe tables. the stock reg is 1:1 ratio, ie for evey 1 psi of boost the reg sees it adds 1 psi of fuel pressure to the injectors by restricting the return fuel flow which pressurises the fuel rail.
the mrs is abit clever ever since the cam replacement due to simultaneous failure of the entire valvetrain which i described as "fairly common with these cars" shes a bit suss of random parts developing random faults. like the worn out manifolds that needed replacement etc etc

[drift-it]

yer i knew that there would be no vac. i was just thinking that 1st didnt get as much boost as 2nd therefore running rich?

[sprattzvx]

yer i knew that there would be no vac. i was just thinking that 1st didnt get as much boost as 2nd therefore running rich?

ahh im with you, but no since its 1:1 less boost is less f/p so should be same bp vs fp ratio arggh im getting a head-spin n shit got ones and zeroes scrolling down my vision matrix styles.....

[Holden202T]

i don't think its pe shot, it seems too far after the stab of the throttle!

[charlay86]

I'm thinking load too, In a lower gear the fuel has less time to burn per revolution due to the higher rate of acceleration.
The PCM calculates the fuelling based on engine speed before it injects it (obviously) but by the time the exhaust valve starts to open the engine is spinning much faster, therefore it didn't have the same amount of time to complete the combustion than it would have if it were accelerating at a lower rate.

[sprattzvx]

hi again guys,
interested to hear any information regarding knock retard decay rates and info on actual knock vs "predicted knock"
always wondered why some knock retard drops away sharply like vertical instantly in logs, but occasionally it drops away in a more calculated neat little stair-case
type arrangement. its not new to me ive seen it a lot, but keen to learn the intricate details of things like this now.
so i would assume the staircase recovery is from actual knock.
also does the delco (vx) have a torque reduction function that reads as knock retard that it uses to soften gear changes etc, and if so is this related to the instantly recovered kr?. i notice the trans go shift kit information states that on some models the pcm will try counter-act the hard shifting.
cheerin for any info.

[antus]

It does have tip-in spark reduction which I think is when you change gears to soften it, but it does not read as knock retard. knock retard is purely what it says.

[VL400]

sprattzvx - Just wondering if your car has traction control? If so that could be the cause of the rich AFR in 1st

[sprattzvx]

sprattzvx - Just wondering if your car has traction control? If so that could be the cause of the rich AFR in 1st

no traction mate. ive given up solving this issue and accepted the shit fueling in first for now. start spending after chrissy possibly some new hardware and if still no luck software also. after that...well i dunno. maybe get a astron sigma