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Discussion Starter #1 (Edited)
it's time for me to put a S-AFC to my ECU to try to bring some extra hp. i borrowed Wide Band from my friend and ran a few spins to see how my A/F ratio looks before tuning the SAFC. what's intresting for me is that up to 4200rpm the ratio is about 13:1, and then suddenly drops to 12:1. i guess that's the point that the VVTi kicks in and the ECU riches the mixture just to make it safer or i don't know what. anyway, the idea is to make the A/F ratio 14:1 trouth the whole rpm range, right?
here are a couple of pics:

 

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Try shrinking the image a bit so people can see it without scrolling.

I would say 13.5:1 is enough, should give you some room for lean conditions.
 

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joecrappa said:
Try shrinking the image a bit so people can see it without scrolling.

I would say 13.5:1 is enough, should give you some room for lean conditions.
True that. Consider this, when the car is on the dyno, you cannot simulate the kind of airflow it gets at 60MPH w/o using some HUGE fans (hyper expensive fans that usually require a chamber built for it). So when you get on the freeway, your 13.5 actually becomes more like 13.8-14.0 (speculation here using some guys wide band readings difference from dyno to real world). Now if you were to dyno leaner than that, you stand the chance of having the computer pull timing to make up for every lean condition that you go into. Less timing = less power!. Remember timing can be more detrimental than fuel (depends on range), eg by bumping the timing the guy with the Emanage Ultimate gained 10rwhp with no other mods on a stock engine.
 

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those numbers look a little lean for driving hard....especially if it is a very hot day & you are hammering the car... in cool weather & those numbers are not too bad, good for power and decent mileage.... but if it gets Hot on you set-up like that you could go lean @ WOT, & that is not so good just dont push it too hjard when it gets hot with that setup...


a 14.7 ratio is "perfect", as they say for optimal fuel combustion & power production etc, but even with the Ecu & computers on these cars today... ou never really run that lean in real world conditions when driving really hard i dont think... at least not safely


it is so hot here we are set up to run a safe 11.8-12.5 ratio during full power runs & boosting 7+ psi...

when it cools off a bit we will retune for a slightly more agressive ratio for better mileage & more optimized power from this setup....


the KILLER thing is that with my Ver.7.0 LMS I-manage, & Wide band AF ratio monitor/ display we can adjust the setup any time we want to richen or fatten up the AF ratio for power or safety, & this thing is still under development... it will be pretty freaking SICK when we are done...LOTS of really cool features to come that are JUST barely starting to be seen on other high end Fuel management setups.
 

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edgy said:
a 14.7 ratio is "perfect", as they say for optimal fuel combustion & power production etc, but even with the Ecu & computers on these cars today... ou never really run that lean in real world conditions when driving really hard i dont think... at least not safely
or 14.6... ;)

which is sometimes called stoichiometric...

here's more info:

http://www.faqs.org/faqs/autos/gasoline-faq/part2/

Typical stoichiometric air-fuel ratios are
[80]:-
6.4 methanol
9.0 ethanol
11.7 MTBE
12.1 ETBE, TAME
14.6 gasoline without oxygenates
 

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2jz_w55, from your list of mods you seem to be n/a. Tuning for a 13.0-13.5 range on the dyno (rich side of that in the higher rpms) should do pretty well for you. This also depends on where in the exhaust you are doing the reading(i.e. @ manifold, @ y, @ tailpipe) I'm guessin you're reading at the tail. The #'s should get a little richer the closer to the head you measure.


BTW Hyper that looks a little familiar ;) #87
http://my.is/forums/showthread.php?t=259162&page=3&highlight=a/f+ratio
 

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Discussion Starter #7
Yogi_TRD said:
2jz_w55, from your list of mods you seem to be n/a. Tuning for a 13.0-13.5 range on the dyno (rich side of that in the higher rpms) should do pretty well for you. This also depends on where in the exhaust you are doing the reading(i.e. @ manifold, @ y, @ tailpipe) I'm guessin you're reading at the tail. The #'s should get a little richer the closer to the head you measure.
yes, my engine is n/a. i have the wideband sensor at the headers, on the place of O2 sensor B1S2, wich is about 20 inches away from the head. those readings are not done on a dyno, i have them from street driving.
 

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2JZ_W55 said:
yes, my engine is n/a. i have the wideband sensor at the headers, on the place of O2 sensor B1S2, wich is about 20 inches away from the head. those readings are not done on a dyno, i have them from street driving.
The #'s you are getting are about right. You could even lean it a tad more, but you really should have a little info on the conditions to help with the tune(uphill/downhill, smooth/rough road, gear, throttle position, etc.). I'm not gonna ask where, just be careful.
 

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Discussion Starter #9
Yogi_TRD said:
The #'s you are getting are about right. You could even lean it a tad more, but you really should have a little info on the conditions to help with the tune(uphill/downhill, smooth/rough road, gear, throttle position, etc.). I'm not gonna ask where, just be careful.
i haven't even installed the S-AFC yet, those numbers are only what the ECU is corecting now. i just wanted to see the numbers so i know if i should buy a S-AFC. the conditions, well in Illinois there isn't realy any uphills/downhills. the road was smooth(i guess). i ran 1st, 2nd and 3th gears and the readings were preaty similar. Throttle positions is only at 100%. someone mention temperature, was about 80F
 

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Hey W55, what equipment are you using to get the reading / chart? I presume this is from a PC. What type of interface did you use to extract this data? Looks to be helpful for street tune
 

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Viola, seems someone here is proving that street tunes are quite a bit different from dyno tunes. the general consensus is that the IS300 runs ~12.5 Af ratio across board. This data log from the street seems to indicate otherwise.

To the poster, I would lean out the 4200 and above RPM to 13.1-13.5 (on the street) and call it a day.
 

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not to go off topic that lil gap shit is what i called happy jump when vvti kicks in, cars they try to make that shit now days to make you "feel faster"
 

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Notice the TPS reading at that point. It drops at the point y'all are seeing the blip.

I assume that is stading for Throttle Position Sensor, in which case that's either a dead signal for a second or someone let up for a moment, but it looks more like just a hickup in the signal that caused the dip.

Because i highly doubt that toyota or lexus would intentionally put a stumble point ot make the VVTI part SEEM faster. That's rediculous.
 

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IceCold4x4 said:
Notice the TPS reading at that point. It drops at the point y'all are seeing the blip.

I assume that is stading for Throttle Position Sensor, in which case that's either a dead signal for a second or someone let up for a moment, but it looks more like just a hickup in the signal that caused the dip.

Because i highly doubt that toyota or lexus would intentionally put a stumble point ot make the VVTI part SEEM faster. That's rediculous.
not just this car, honda with vtec, lan evo too if u put a boost gauge, it jumps 0.2 bar but back to regular boost so u feel faster,both of them have the same crap, it jumps so u feel faster, but it's not, but over the map u'll find vtec has less jump.

i've seen bmw vano's kick in map, it's really really smooth.
 

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the VVTI kicks in pretty dang smooth also

But back ot the point of the tread, the Throttle position sensor shows a dip right at the same spot we are seeing the dip in a/f ratio. So that is the culprit i'd imagine. So if it does this repeatedly i'd be very curious as to why.
 

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IceCold4x4 said:
the VVTI kicks in pretty dang smooth also

But back ot the point of the tread, the Throttle position sensor shows a dip right at the same spot we are seeing the dip in a/f ratio. So that is the culprit i'd imagine. So if it does this repeatedly i'd be very curious as to why.
no it doesn't, i'm talking about on the graph, no gap for vano, i'll try to find one so u know what i'm talking about
 

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The TPS goes down when he takes his foot off the gas to shift (look at the RPM chart) and the AFR shoots way up for a split second past 20. It is ALL normal. That graph updates in real time via your laptop plugged in to a Zeitronic wideband.
 

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Discussion Starter #18
Sunburn said:
The TPS goes down when he takes his foot off the gas to shift (look at the RPM chart) and the AFR shoots way up for a split second past 20. It is ALL normal. That graph updates in real time via your laptop plugged in to a Zeitronic wideband.
that's right, the TPS goes down when i shift, and i think that the ECU has a fuel cut at that point and then sprays fuel for cooling, that's why the AFR goes up and down. but thats at about 6400rpm, when i shift. the deep i'm tolkin about is at about 4400rpm. the values at the right side are at where the white line is.
and yes, this wide band is Zetronix
http://www.zeitronix.com/Products/zt2/zt2.htm
and i'm getting the graphs from a laptop hucked up to it.
btw, today i went to the track and my best 1/4mile time was 14.786 wich i think should be preaty good for a N/A IS300
 

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Perfectly normal tune for the stock ECU. Thanks for posting the graphs... as you can see, the stock ECU is tuning to ~12:1 throughout most of the RPM range.

Get an SAFC and lean it out to 13.5/14:1 and you'll be all set.

+rep!
 

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it may just be the difference in ignition timing between my car and an AFC'd car, but my car is noticebly slower when i run much leaner than 13.5:1. I have been tuning for around 13.0:1 for the street. just to make sure things are safe when the computer changes for temp and things like that.


As far as the dip in the power band around the VVTi point, http://www.transonicracinginnovations.com/gallery/albums/GReddy-Emanage-install/Lexus_dyno.jpg

there is my stock vs EMU dyno chart, you can see stock the dip was there, and more drawn out, but after the tune it pretty noticeable. Just need to move the VVTi point around a little to see if it helps or hurts that dip at all. Most VTEC honda that dip can be eliminated w/ proper tuning, so i'm sure the IS could be too.
 
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