grabbem88

So what would you do if you was tuning my car.

I think that’s a fair question.

so with o2 I can tell computer hey that’s ok leave it alone but don’t let it go past that?

ULTM8Z

Essentially yeah. Let's say the O2 swing point is set at 450 mV, the upper threshold is 500 mV and the lower threshold is 400 mV. Then as long as your O2 sends back voltages to the ECM tha'ts between 400 and 500mV, the ECM won't react with fuel trimming. It wants to be perfectly at 450, but will allow up to 500 and down to 400 before doing anything.

If the O2 voltage goes above 500mV, the ECM will pull fuel out, and your INT will drop. If the INT stays down below 128 for enough time, the BLM will start to drop as well until the O2 voltages get back withing that 400-500 mV range.

If O2 goes below 400 mV, the opposite happens. INT will go up and drag the BLM up over 128 until O2 voltages get back within the 400-500 mV range.

So, like I said before... what I would do is go back to your stock VE tables.

If you're seeing low BLMs, it means the O2 swing points are too low and the ECM thinks you're running rich. Raise the O2 swing points.

If you're seeing high BLM's it means the O2 swing points are too high and the ECM thinks you're running lean. Lower the O2 swing points.

Lower airflows in the O2 swing points table generally correspond to the lower MAP values in the VE tables. Higher airflows in the O2 swing points table generally correspond to higher MAP values in the VE tables.

So you may not be adding uniform amounts to the O2 tables... you may have to add more at higher air flows and less at lower airflows. You may even subtract from the tables at lower air flows. You just have to see where your BLMs are and adjust accordingly.

Playing with the O2 tables may not get you to 128 everywhere exactly, but it'll get you a good head start on where to take the VE tables after the car (hopefully) feels right by seat of the pants.

Tuning can be a little bit of an art form... I've been doing it for ~20 years, but focusing mainly on the 3rd gen TPI stuff, though the principle is basically the same (especially on 93 LT1's since they're also speed density).

grabbem88

Appreciate the help some is confusing but I’ll get there...

grabbem88

So it’s possible my cam is dumping more oxygen out (unburned) and o2 is telling computer hey this bitch is lean so more fuel is being added or my unburned is so rich the computer is trying to lean me out causing my 13-16 infux? Cause I know in open loop I was 12.2-13.9 kinda where my PE is at..

I think in my log 30-55kpa I was above 128

ULTM8Z

Exactly... O2 sensor doesn't measure unburned fuel. As the name suggests, it measures unburned O2.

Take an extreme case... if you had no spark in a cylinder (broken plug wire, fouled plug, etc), it would draw in a fresh mixture through the intake, do nothing with it, and then dump that mixture out the exhaust. The O2 sensor would see a ton of unburned O2 and tell the ECM you're running supper lean, at which point the ECM would start adding tons of fuel to that bank of cylinders tying to compensate for what it sees as a lean condition.. And because of that, the other cylinders on that bank would get a ton of extra fuel that they don't need because of that one bad cylinder.

I think once you start playing around with it and seeing how it responds, you'll get an idea of what's going on.

Injuneer

Isn’t that basically the issue running at low RPM, closed loop, with a cam with a lot of overlap - there's air and fuel flowing out with the exhaust?

ULTM8Z

Yep. High overlap on the cam can cause unburned mixture going right out the exhaust.

grabbem88

my problem is I don’t know what most functions do. Hence the pcmforless tune and Solomon tune not saying they wouldn’t have gotten it eventually but spend an extra $50 after a free tune cause it still isn’t right drove me to buy my own stuff. Rest assured if I come across $3500 I’m going Holley/tq head but I won’t so I’ll tune what I already have..$3500 can get me better stuff that “need”. Like a 9 inch with 4.10’s lol.

but I got priceless info from that will definitely help and I hope it’s ok to message you once in a while you know have an experienced eye on my tuning

ULTM8Z

No problem.

Could try this too... I found some injector voltage offsets from Bosch 30 lb injectors (Ford runs these as Ford Motorsport). I think yours are actually used by Volvo.

https://performanceparts.ford.com/pa...-9593-b302.pdf

They're not exactly the same p/n as yours, but the family of injector looks the same as yours... the "fat" injectors. In the world of Bosch-III's "skinny's" like I'm running, I've gotten lucky using voltage offsets from injectors with different p/n's but the same family because they ended up being close enough. Any luck the same will hold true for your style injectors.

These guys converted it over to the DA3 LT1 tables...

https://forum.hptuners.com/showthrea...l=1#post365168

So what I would do along with reseting your VE tables back to stock (and again, prior to playing with the O2 swing points)... go to the table Injector PW Correction vs Battery Voltage and input these values. Just the whole number part is fine (don't need all the decimal places).

This essentially tells the ECM what kind of injectors you're running. Like I said earlier, Injectors are more than just their advertised flow rate. They have open and close times and ramp rates that vary with the system voltage being applied to them.

grabbem88

funny you say this cause i was just comparing tuner A to tuner B one has my injectors at 27 the other tuner has 30??

i also compared some others stuff i like the timing tables on one and ve on the other maybe i can frankenstein the two lol the tuner x file is a improved on tuner A file but its working better than other two its a mess for sure

grabbem88

plus there numbers are way different so I don’t know.

Injuneer

Where did you get those injectors? There are infinite quantities of very accurate looking, cheap (less than $100 for a set of 8), extremely poor quality Chinese "Bosch" rip-offs out there.

You might want to look at larger injectors as well. That's not going to solve your surge problem, but there is a nexus of your estimated flywheel HP, upper BSFC/duty cycle limit for 30 #/Hr injectors, and flow capability for the stock 48mm throttle body. If you are going to fall back on a mail order tuner, I can give you the name of one who is much more capable than the two you mentioned.

grabbem88

moe Bailey? Yeah he told me no..he doesn’t do my car???

on the injectors thing I helped put them and take them out so the injectors are Ford 30lb
400hp is nothing for 30lb so not sure why I need bigger???

grabbem88

I also tried the tps enrichment the o2 swing.

the only thing that seems to work is taking my coolant vs closed loop to 100.25c.

ULTM8Z

The other thing to try is to put in those voltage offsets I showed earlier. I remember when my offsets were incorrect, no amount of tuning could get the car to behave properly. When I got the correct ones finally, I could tell immediately on start up that it was right (it just felt and sounded spot on). After that, dialing in the tune was very easy.

Maybe it's a similar situation here?

Keep an eye on the WB O2 gauge though and don't nail the throttle right away... ensure your AFR's are good (not too lean) before laying into it.