is there a "rule of thumb" for what A/F you "should" be at for a given RPM while under a WOT run, from start of run to end of run?

should it be a gradual slope downwards as in, higher A/F in the lower RPM range gradualy getting a lower A/F in the upper RPM range?

my eductaed guess would be yes since you need more fuel in relation to boost, but im just curious if there is a rule of thumb for how much at what rpm, etc...

thanx

Originally posted by tim97rs
is there a "rule of thumb" for what A/F you "should" be at for a given RPM while under a WOT run, from start of run to end of run? should it be a gradual slope downwards as in, higher A/F in the lower RPM range gradualy getting a lower A/F in the upper RPM range? my eductaed guess would be yes since you need more fuel in relation to boost, but im just curious if there is a rule of thumb for how much at what rpm, etc... thanx

RPM doesn't have much to do with AFRs... Well.. Shit.. tough question, it does, but lets put it this way. If your foot is mashing the gas pedal, you need to see at least 11.5 (to be safe) on the AFRs. AFRs dont know how much boost in relation to fuel.. You just need to see a good constant AFR reading throuhout the band.

okay, let me clarify...


this is a typical WOT reading for me. note how the AF slopes down as the rpm/boost increases. my question is something along the lines of should i be tuning for an 11.5 A/F thru the ENTIRE range from the second i floor i,t or is a slope the correct thing to see? does my question make sense?

The downward slope between your 2nd and 3rd measurement marks is a good slope. You're A/F ratio is perfect there. The A/F ratio between the 1st and 2nd measurement marks (spool up) looks like it either has a lean spot, or you lifted slightly and threw rhe ECU back into closed loop for a second.

Originally posted by dougie2
The downward slope between your 2nd and 3rd measurement marks is a good slope. You're A/F ratio is perfect there. The A/F ratio between the 1st and 2nd measurement marks (spool up) looks like it either has a lean spot, or you lifted slightly and threw rhe ECU back into closed loop for a second.

what ^^^^^^ said.

it must a lean spot, all my runs do that. wasen't sure if that was "normal" or not. so i should do some tuning there for sure... humm....

so, idealy it "should" look like a nice steady slope from the point i get on it to the end of the run, right?

Originally posted by tim97rs
it must a lean spot, all my runs do that. wasen't sure if that was "normal" or not. so i should do some tuning there for sure... humm.... so, idealy it "should" look like a nice steady slope from the point i get on it to the end of the run, right?

Right. But for some reason I didn't notice the A/F ratio at the end of the run the first time I looked at the graph. Where it dips from 11 to 10.5 toards the end, you should lean it out some there and keep it over 11:1.

tuning is fun isn't it?

well, after re-looking at this i never really got my initial question answered all that well.
should the A/F line look more like the Red line as opposed to the purple line?

is there a general rule of thumb (at least for our cars) of what A/F range you should be in compared to a particular RPM range, or is it all just relivant to the car?
i am talking about a WOT run.

just need clarification before ihit the dyno next week.
thanks

You'll NEVER get an A/F ratio graph slope like the red line you drew... it's always going to be a little squigly. You DO want to eliminate large jumps or dips though. The purple line between measurement mark 2 & 3 is nice and smooth I hope that answers your question. When I get home I'll try to find some good graphs that illustrate what I'm trying to say.

Specific fuel required is different with every engine. Assuming you're running the HRC S16G turbo and don't have any super trick intake/exhaust work, here is MY recommendation based on my experience.

13.0-14.0 Idle & Cruise
12.0-13.0 1-10 PSI
12.0-12.5 10-15 PSI
11.5-12.0 15-20 PSI
11.3-11.7 21-UP PSI

Those aren't concrete numbers or anything, just my recommendation.

Also remember that if you tune for 11.3:1 AFR on the dyno, it's going to end up being more like 11.7:1 on the street. This is because of the varying loads and atmospheric & weather changes. The chart I posted above is based on street tuning since that's where I do 85% of my tuning for engines in daily-driven vehicles.

Just an observation for those who know more than my dumb ass:

The point where the red line crosses the green line is almost exactly 0psi boost.

He has an 034efi 8 injector system.

AIC onset?

Originally posted by thedawg
The point where the red line crosses the green line is almost exactly 0psi boost.

You're 100% correct. That lean condition at 0 vac needs fixed ASAP.

Bingo! Thanx.. thats what i was lookin for...

heheh....i recognize that graph quite well :) innovative lm-1 ownssssssssss

dougie gave the best advice, cruising the ecu sets the af at about 14.5, my afr cruising camps at around 14.1 afr. our cars tend to make the most power right around 11.5-11.7 afr. just watch your timing. air fuel and RPM are very, very hand in hand i dont know WTF you're talking about siu...but then again, neither do you.

what ive noticed from tuning my car is the fuel is pulled back in the lower and higher rpm's and right around peak torque is where the fuel really dumps, thats where you need it.

hit me up on aim and we'll talk :) that lm-1 kicks ass doesnt it :)

Originally posted by dougie2

Originally posted by thedawg The point where the red line crosses the green line is almost exactly 0psi boost.

You're 100% correct. That lean condition at 0 vac needs fixed ASAP.

the torque curve perks up as soon as the motor see's 0, lean it out before boost...and start richening up after

well, get your ass ON AIM....

Originally posted by turbo8u
that lm-1 kicks ass doesnt it :)

I use the LM-1 with LMA-3 (AuxBox). It kicks ass indeed. I log AFR, RPM, TPS, MAP, EGT, CLT, IAT. I can log anything else if a choose- fuel pressure, oil pressure, more EGTs, CHT, whatever. I can honestly say it's one of my best investments ever!

Originally posted by dougie2

Originally posted by turbo8u that lm-1 kicks ass doesnt it :)

I use the LM-1 with LMA-3 (AuxBox). It kicks ass indeed. I log AFR, RPM, TPS, MAP, EGT, CLT, IAT. I can log anything else if a choose- fuel pressure, oil pressure, more EGTs, CHT, whatever. I can honestly say it's one of my best investments ever!

whoa whoa whoa wait hold up! how come i didnt know about that other shit? all i log is throttle position, rpm and air fuel...how are you logging EGT and all that? i use my datalogger and wideband daily and tune on the fly like there is no tomorrow. i'd LOVE to have more inputs though, thatd make me happy :)...enlighten me

definately a good investment though, i agree...

my sensor crapped on me after 180 miles though, lol...but they just scratched their heads and replaced the whole damn thing

edit: get in the chat fellas :thumbsup

i really shoulg break down and buy the Aux box, right now all i have is the RPM converter and a home made Boost sensor (corbins) to read boost signal. turby, the aux box just got released about a month ago./.. AND GET YOUR ASS ON AIM!

Originally posted by thedawg
Just an observation for those who know more than my dumb ass: The point where the red line crosses the green line is almost exactly 0psi boost. He has an 034efi 8 injector system. AIC onset?

No, not true. the bottom numbers on the graph is time, not psi. the point where the red crosses the green on the orig. graph is approx. 2.5 to 3 psi. but keep in mind i have that homemade boost sensor, so i could be off a small amount.

Originally posted by tim97rs

Originally posted by thedawg Just an observation for those who know more than my dumb ass: The point where the red line crosses the green line is almost exactly 0psi boost. He has an 034efi 8 injector system. AIC onset?

No, not true. the bottom numbers on the graph is time, not psi. the point where the red crosses the green on the orig. graph is approx. 2.5 to 3 psi. but keep in mind i have that homemade boost sensor, so i could be off a small amount.

Ok, well that makes even more sense then.

Since the green line (boost) at 14.0 seconds is 0 psi, and it is going lean right at 14.0 seconds, the factory ECU tries to compensate up to about 2psi boost, and then the secondary injectors take over and bring the AFR back to normal again.

Try moving your 8injector onset -2 or -3 psi earlier than whatever it is set at now.