Kinj flow

[Asho88]

Hey lads I’m slowly getting my arse into tuning the old girl I’m just trying to figure out my kinj flow and whether I’m playing with the right settings. It’s a Holden 253 with 304 efi with 440cc injectors setup and a mild cam. I calculated the kinj at around 0.050 but I’m seeing with the wideband setup that it’s running rich compared to what it’s targeting so I’ve been adjusting adjusting it down and got it down 0.023 which is still reading rich but any lower and it stalls.

[antus]

I'm actually doing similar on my car at the moment, with some custom made chinese 440cc injectors that I do not have real data for. These were needed as I couldnt find anything off the shelf for this flow rate that would fit the fuel rail in this car and in high impedance. I had to divide the cranking tables by 2.6 and set the injector flow to .05 but in my case it is OK at that level. It'll be rich when you start it up because of the cold start enrichments probably being wrong, so you need to warm it up before you can trust the data and then come back to the cold start enrichment. I found that in my case my no-name 440cc (42lb) injectors seem to open more quickly than the previous 13lb despite most of what I read saying they would open slower due to more mass in the pintle. I guess the new injectors have stronger coils than the old. I have reduced the opening times vs voltage to improve the AFRs at idle. I'm currently considering if I should look at the low pulsewidth adder too. I think the injectors are running in the non-linear part of the slope right at the bottom at idle and this table is to correct for that. The other critical thing is because of the size of the 440c the injection time in double fire mode at idle was too short (at least with the incorrect opening time data or maybe too short in total, we'll see) and I had to set the single fire mode flag to get stable idle. When I had it idling OK and turned single fire mode off I got an immediate stall. I'm thinking (thanks to a suggestion from Jayme) that if I put something under the throttle to hold it at about 1500 or 2000 rpm at idle so that the pulse widths are longer, then I might get it to the point where I can set and clear single fire mode without a stall and if that's the case it should be possible to tweak opening times until that flag makes no difference to AFRs. That'll mean opening times are dialed in correctly. The suggestion is to then to run the car on a flat battery and disconnect the alternator and repeat it for a lower voltage opening time, then use the two known good values to scale the rest of the opening time table. I don't have a bad battery like that and I don't want to flatten a good one down that low and if I did i'm not sure it'd crank the car, so a few things to think about that might work if trying that first.

What I am running are these changes. My 4 Cyl has 498.75cc cylinders which is part of the injector flow calculation. All I have done is change from Bosch 0 280 150 205 Injectors (13lb) to the 440cc 42lb from a reasonably well tuned bin before hand. There is more to do before its good on the new injectors, but it is drivable and it starts and idles straight away hot or cold engine and the AFRs are close enough to do a full load pull through the rev range.

Changes (work in progress):

Screenshot 2025-08-24 185358.png

The old injectors were: https://www.ebay.com.au/p/244529009

s-l1600 (1).jpg

And the new ones more like the ones on the table here:

20250803_125704.jpg

Still EV1 hose barb type, the opening time difference was quite unexpected. This shot is a home made injector tester I built with an ebay mosfet board and an esp32 board and a bit of code to drive it. The signal was terrible compared to what an ECM outputs but I just used it to drive 2 injectors at a time in a repeatable way using the car fuel pump and regulator so I could put together a matched set of 4 from 8 units. I'll have to write up another thread about that. It wasn't good enough to profile the injectors but it did show that 6 of them were very closely matched, one was a little out, and one was a serious outlier (even though it was still within the official 5% the vendor stated). So I got a good set of 4 with 2 spares and the other 2 I will probably never use.

[Asho88]

Yeah I’ve adjusted the cranking tables as per your previous advice it starts and runs well a little smokey but as above it’ll be runner richer to suit the cold engine. Though what I was looking at was its target though you are correct there would be to much going on in the warm up process to get accurate. I’ve got the dead times and entered those. Though I’ve been thinking about it and I’m probably (for a start best to set the kinj flow to the calculated rate and adjust the ve table as it’ll be opening the injectors based on the original 19cc figures so probably to much. Am I right in thinking that?

[antus]

that's pretty right, but it might be too far out to run properly to get up to temperatue. so you might need to fudge it a couple of times as it warms up just to keep it happy until the engine is as temp. I found going straight for values that may be right can cause other problems while a couple of these tables are all not right. But the biggest gotcha is that single fire mode for injectors of this size. I think you need that else you'll have problems at idle while you are dialing it all in.

I'd say the order of things is:

1) get it starting (obviously) and you've done this
2) get the injector rate right when the engine is up to temperature and may need to be fudged a couple of times as it warms up
3) do what you can to get dead times right
4) do something similar to the suggestion above for dead times so you can toggle single fire mode on and off and see no change in AFRs. This will determine if you can use those injectors in double fire mode and deliver small enough injection for a good idle. You can leave it on single fire and need to for some large injectors.
5) Tune VE
6) Tune AE/DE
7) Tune Warmup tables so you get good behavior from cold.

[Asho88]

It runs pretty well just a bit smokey but otherwise good.ok I’ll have to look into the single fire mode. That list sounds spot on thank you. What is AE/DE? Cheers

[antus]

Accelleration Enrichment and Decelleration Enleanment. The main one is the table AE - AE Multiplier Vs Engine RPM. Use that to scale the enrichment so your AFRs hit about 12 or 12.5:1 when you go wide open throttle. I havnt changed the enleanment, but that can be used to add or reduce unburnt fuel in the exhaust for crackle or not when you come off the throttle and are slowing down.

[Asho88]

Awesome thank you makes sense cheers

[The1]

You can usually fire the car up then disconnect positive on the battery and just run with the alternator only, gets you in 12's or 13's which is lower than with battery, depending on your load, if you have decent load dont run it to long alternator will get quite hot!

[Asho88]

I have the dead time settings and they’re entered though after running it a couple of times I’m noticing it is flooding gets to a point and shuts off or if I turn it off it won’t restart unless left to sit then still I’ve gotta open the throttle body to get it start up.

[brindo]

I had 42lb Ford Motorsport EV1 injectors in the stroker 5.0, and they were way too big. Changing to single fire made a huge difference but it was not a long term fix.
Sounds like you are up to Step 5 from Antus’ advice.
Have a look at the VE table where its idling using the data trace and work on those cells to get an idea of where it should be.