What AFPR Set Pressure for 19lb Injectors?

[squidmaster]

Ahh, my phone corrected PWM to pump.... That's where we're getting in trouble! Unless you're saying I'm wrong about something else, because I'm absolutely not wrong.

[mpowerful]

PWM makes 100x more sense hahaha. :)

[squidmaster]

;)

[nando]

I've seen you talk about this before, but I never noticed if you had given any readings or data to support that the car was performing within an ideal range. Because if I were to go out to my car right now (with 19#), load the original map into it, enable o2 feedback, and just wait, my idle AFR would go from about 16 to between 13 and 14. While the car may still idle at that AFR, it won't be very smooth and just ends up wasting gas. When I start to drive, my cruising AFRs change from 15.5-16 to 12.7-13.5 after a while of learning the trim. And while I may still be able to drive the car with that, again, a waste of fuel and it just won't run as well. Going into WOT you might start seeing numbers in the 10s or 11s or 12s; for an NA car that is hardly ideal. So that's why I would like to see what you have experienced with the injectors on a stock computer and stock chip. There has to be some reason why they apparently work great for you and a couple of other people, while everyone else finds them hurtful on stock tunes.

again, I did it for years. my MPG didn't change, (21 on average, all stock motor otherwise), so I know my AFRs weren't rich.

[Bullet Ride]

I've seen you talk about this before, but I never noticed if you had given any readings or data to support that the car was performing within an ideal range.

Although I don't have any quantitative data that I can post. I can give you some qualitative data. When I first got my E30 I installed an M30 AFM along with a wideband O2 to monitor the AFRs. At first the car ran a bit lean but once the fuel trims adjusted it was fine. After that I put in the 19# injectors and drove around for a while on the stock chip with, again after the fuel trim adjusted the AFRs were normal and stable. This was all with the stock FPR.

I'd say the cause of your troubles is your adjustable FPR. Put the stock one back in if you have it. The car is more than capable of handling 19# injectors on its own.

[squidmaster]

I've never had a reason to stay on a stock tune for long enough to see the Afr reason itself out. Perhaps the ltft can handle the job just fine. That's pretty good. You say you didn't get any Afr readings but also say they were normal and stable? How did you verify?

Also 21mpg seems pretty low. Im getting 25-28.

[nando]

I've never had a reason to stay on a stock tune for long enough to see the Afr reason itself out. Perhaps the ltft can handle the job just fine. That's pretty good. You say you didn't get any Afr readings but also say they were normal and stable? How did you verify?

Also 21mpg seems pretty low. Im getting 25-28.

well, my MPG didn't change (and it ran just fine prior). So I can only reason that the actual fuel metered through the injectors didn't change either. the car definitely ran better overall.

later I built my stroker and ran the same setup. I put it on a dyno and it was actually a little too lean.

as far as mileage, that's nice. this was an automatic ix, about 40% city.

[squidmaster]

Haha then 21 seems pretty good!

[Bullet Ride]

You say you didn't get any Afr readings but also say they were normal and stable? How did you verify?

I have a wideband O2 in the car, so I could watch the gauge to see how the AFRs adjusted over time. It only really took several km of driving before it was dialled in.

I was just referring to the fact that I don't have a datalog that I can post to actually back up what it is that I'm saying, so I can understand from your end it just looks like conjecture.

[digger]

Ahh, my phone corrected PWM to pump.... That's where we're getting in trouble! Unless you're saying I'm wrong about something else, because I'm absolutely not wrong.

thought you had lost the plot , varying pump voltage alone would be a less than ideal way to control things IMO ......lol

[digger]

yeah, I don't agree. every car these days uses an O2 sensor as an important feedback loop. It's the only way the DME has any clue if it's giving the right amount of fuel to the engine. the O2 sensor that really only affects emissions is the post-cat sensor.

also, if your base fuel map is close to what it should be to begin with, you shouldn't need much of a fuel trim anyway, just enough to keep things on target as the engine ages. even the part throttle fuel map isn't necessarily just straight 1.0 lambda..

about % corrections. I ran 19# injectors on a stock chip for years without issue, but everything was working correctly. if the DME isn't properly metering air and getting accurate O2 feedback in the first place, then you could be so far out on your fuel adaptations to begin with that there's nothing left for the injector size change.

all the CAT equipped cars use O2 sensor for emissions reasons targeting at 14.7:1, this does not bring best economy nor best power it helps meet ever tightening laws.

its not a bad idea to have to have closed loop feedback but targeting 14.7:1 (as motronic does) is not ideal was what i was getting at.

you don't need feedback, it can help but ive not run it for about 6 years but because i have a cat more often than not the engine runs at stoich as it was tuned to. It doesnt wear out enough to worry about miniscule minor variations and with MAP vacuum leaks are not the same problem they are on a AFM or MAF system so i dont need any feedback to achieve the desired AFR. plus im always screwing around with it

[nando]

Then change the target. Its NOT just a straight 1.0 lambda target, its a fuel map with many values, not all of them are set to 1.0 anyway.

[squidmaster]

Stock motronic has lower than 1 lambda values, which are based on rpm. I can get them in a couple of minutes.

[squidmaster]

Some of the Honda systems I have worked with will shoot for straight 14.7 while in closed loop however

[digger]

my motronic was always stoich in closed loop at idle and low load cruise from what i observed, at medium loads and rpm i dont recall. when i had motronic custom tuned the guy said a bit richer than what Motronic gave in closed loop performed better but i needed to run W/O O2 to keep it there....i did connect it at some point and had a missfire traced back to dodgey O2 so its another part that fails and if you can tune without it there is no difference

with aftermarket ECU retune the map was such that AFR in open loop were what they were supposed to be so i never bothered setting up the closed loop option. Im going to do an Alpha N setup soon so might do closed loop for it since at low throttle openings it can be finicky depending how clean the TPS signal is