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Tech Post: Why Intakes Need a Retune


covertrussian

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I recently made a quick and dirty warm air intake (WAI) out of the stock MAF housing a flow stack and some couplers. This post will cover the tune changes in layman's terms and the dangers of intakes without a retune.

 

Keep in mind this is just a proof of concept intake and is not meant to be permanent in it's current state. It's function is similar to a lot of non-airboxed intakes on the market.

http://legacygt.com/forums/attachment.php?attachmentid=254721&stc=1&d=1504035908

http://legacygt.com/forums/attachment.php?attachmentid=254722&stc=1&d=1504035908

 

 

Did a log with the new intake and compared it another log from the same road. As you can see I stopped doing the pull around 4500rpm, I didn't want to risk it going further.

http://legacygt.com/forums/attachment.php?attachmentid=254730&stc=1&d=1504035908

 

First thing that really stands out is much leaner AFR's, about 3 points leaner, instead of a good and safe 10.5-11 AFR's, car leaned out to 13-13.5 AFR. Next thing was overboosting, about .5psi more. Running more boost and being lean will absolutely destroy your engine. As you can see my AFR's were in 13's, when max safe is around 11.5 AFR on stock TMIC.

 

Now that we covered the easy to spot things, lets look at the hidden reason behind such drastic AFR changes.

 

Mass Airflow (g/s)

Not exactly sure why, but the less restrictive intake caused the mass airflow reading to be much lower, about 25% lower. The ECU basically thinks that we are receiving less air, thus it adds less fuel through the fuel maps when in fact we are receiving more air then before.

http://legacygt.com/forums/attachment.php?attachmentid=254728&stc=1&d=1504035908

 

My thought on this is, it should have been reverse, more airflow from intake should cool the MAF hot wire more, needing more voltage to keep it warm, thus reading higher MAF Voltage, which calculates to a higher grams per second airflow. Maybe someone more knowledgeable on this can chime in?

 

Engine Load (g/rev)

Because the ECU is calculating lower grams per second, our Engine Load grams per rev is now much lower.

http://legacygt.com/forums/attachment.php?attachmentid=254727&stc=1&d=1504035908

 

This can be visualized through the trace line. We are stuck at 1.80 g/rev instead of 2.40 g/rev. On this map 1.80 g/rev is meant for about 7psi of boost and 2.40 g/rev is meant for about 14psi. New intake overboosts to 14.2psi and stays at 1.80g/rev, this causes the car to run 7psi's fuel values while your actually at 14psi.

http://legacygt.com/forums/attachment.php?attachmentid=254726&stc=1&d=1504035908

 

Timing

Not only are you running leaner, you are also running more timing, this as because we are stuck in a lower column meant for less boost.

http://legacygt.com/forums/attachment.php?attachmentid=254729&d=1504035908

 

Further visualized in this map trace (ignore the bottom trace for now). As you can see the car is running 21* instead of 13-17*. That alone, even with non lean AFR's can kill a motor.

http://legacygt.com/forums/attachment.php?attachmentid=254725&stc=1&d=1504035908

 

 

Tuning for these changes

Finally, if you haven't been pushed away from intakes all together, we can start adjusting the tune for this mod. These are just the basics, keep in mind that every intake is different and might not be as easy to adjust the tune for (especially if the MAF tube diameter and MAF placement is different from stock).

 

MAF Sensor Scaling

First I calculated the difference between the Mass Airflows between the two graphs and came up with about 24%. I increased the MAF Scaling by 25%.

 

Initial & Max Wastegate Duty Cycle Tables

Next I calculated the difference between the amount of boost I was running, came up with 7.7%, removed 8% from all of the values.

 

Here is the boost map trace, we are back to our previous boost numbers. Now you could always keep the added boost and just adjust your timing and fuel for added PSI, but I personally wanted a 1:1 comparison of the power gains from the intake only.

http://legacygt.com/forums/attachment.php?attachmentid=254723&stc=1&d=1504035908

 

Primary Open Loop Fueling

I didn't have to make any changes to the fuel table because my AFR's were identical to what they were before.

 

This map trace compares the three runs AFR's, as you can see the most MAF scaling increase and boost decrease AFR's were back to what they were before.

http://legacygt.com/forums/attachment.php?attachmentid=254724&stc=1&d=1504035908

 

Ignition Base Timing

At first I didn't have to adjust the timing, but driving higher IAT (which a WAI intake is more prone to higher IAT's) I saw some knock and reduced timing up top.

 

Timing Compensation (IAT)

Warm air intakes soak up a lot of heat and hit high IAT's (Intake Air Temperatures) much faster then with stock intake. On a 90*F day sitting at a stop light and slow city driving got me 150*F in just a few minutes. I saw the ECU pulling timing due to knock at fairly low loads (1.00-1.20g/rev).

 

You should probably update the Timing compensation table to retard more timing at higher IAT's to avoid detonation.

 

 

Power Gains

The stock intake is a very good cold air intake, but while it can deliver colder air it's still very restrictive. The common notion that an intake is not needed or doesn't gain any power below 300-350hp has been debunked by GrimmSpeed, with their intake making around 20whp over stock intake at similar boost levels and minimal tuning. Their intake did so well because it has minimal bends and has a very well designed airbox that reduces hot engine air contamination.

 

When my IAT's stayed down (drive around for couple miles before doing the pull) I saw similar gains in Virtual Dyno on the same stretch of road 30 minutes apart.

http://legacygt.com/forums/attachment.php?attachmentid=254731&stc=1&d=1504035937

 

 

Conclusion

The biggest issue is with a new intake is MAF voltage being less, which gets calculated to lower engine load, which makes your ECU to run less fuel and more timing for the same amount of boost.

 

Next issue is WAI specific: keeping the IAT's low to avoid timing retard (less timing = less power) and to avoid detonation. Thus I now believe a sealed Airbox is a must, either buy one with it, or make one for your existing intake.

 

I also found that keeping the MAF location and diameter the same as stock (because I'm using the stock maf housing), still requires a retune, even switching to a drop in high flow filter messed with MAF voltages.

WAIv1_007.thumb.JPG.37ca87e23235d1f6844ac7e78bd7ce83.JPG

WAIv1_013.thumb.jpg.88568bf3367bafa2f37391488e535e85.jpg

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412418445_TraceFuel-StockvsWAIvsWAItuned.thumb.png.3ea6b11bf5dfec5187db7ea9e8b340b4.png

1077536571_TraceTiming-StockvsWAIvsWAItuned.thumb.png.1e4fe51a2936640032a1b50aea3628bf.png

920200841_TraceWBO2-FuelMap.png.200f14b11be8524b3ef737096d395ab6.png

2040630965_Tune-WAIv1-Load.thumb.png.a81ce6c78d69ce8e7fe88fed659d7608.png

149651161_Tune-WAIv1-MassAirflow.thumb.png.902ee136165159a8f2e02e34bb1e4b87.png

1452798432_Tune-WAIv1-Timing.thumb.png.4d367087db468f7c06752e56f2d0ec30.png

868106763_VDyno-StockAirboxvsWAIv1IntakebeforeTune.thumb.png.1c7665ba4c430983c6d94c7f98f4483c.png

123789082_VDyno-StockvsWAIv1BPIFlowstack.thumb.png.9041985a6fbf961be8992240a1f76902.png

05 LGT 16G 14psi 290whp/30mpg (SOLD)

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Ecu is registering less air because there is more air flowing AROUND the maf not necessarily against it.

 

I think that only applies to going bigger diameter pipe (over 70mm ID) or if you don't have a flow straightener, but since I'm using the stock housing with straightener I don't think this is the case. Perhaps the 90* turn that air has to make on stock airbox is what causes it go more into the MAF it self?

 

 

What I would love to try is using the stock airbox and just relocating the MAF housing to a better spot and seeing if it makes a difference. :lol:

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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I think it applies anytime you change the manner in which the air flows through the maf. Think of it this way. More air might follow the outside of a bend and therefore restrict the straight portion of the tube that comes before it. You changed the bends and the *way* air flows through the tube. The maf is now simply registering less air because more air is able to flow around it.
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It's also the flow stack that is making it leaner (not 100% sure if it's by reducing the read MAF voltage). I got an amsoil built in flow stack filter (3"), installed it and was gonna do some logging but my Tactrix cable died on me so got no logs to compare, but looking at the wideband my AFR's dipped below 10's (Uego doesn't read below 10 on gauge sadly).

 

Once I can log again, I'll do more testing, will see if the full sized flow stack is lowering MAF voltage or if it's just flowing more air and hence is leaner.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 2 months later...

K&N Typhoon

 

K&N claims that the Typhoon intake does not need a retune, most of us know not to trust those statements, but new members tend to trust K&N's word over ours. For this reason wanted to test the stock intake and the K&N Typhoon and see for myself if it needs a retune and why it needs a retune.

 

If you want to read the quick explanation, just read the AFR section. After the AFR section I will dig further into the technical details.

 

AFR

Tune stayed the same, the logs were done within an hour of each other.

http://legacygt.com/forums/attachment.php?attachmentid=254733&stc=1&d=1504036515

 

Here's a more detailed MAP trace of AFR averages:

http://legacygt.com/forums/attachment.php?attachmentid=254739&stc=1&d=1504036515

 

This is on my Stage 2 tune which is slightly leaner then 100% stock tune (10.00-10.50afr). Stock intake AFR's are close to 10.50, with the K&N they were close to 11.40. That's almost a whole AFR point leaner, TMIC cars need to be 11.00 afr or less to be safe. Even on a 100% stock car you would still be pushing above 11.00 AFR.

 

Next is Boost, this intake cased me to overboost by .5-1psi. This is not a big issue if your tuned for it, but remember K&N says no tune is required.

 

K&N resized the diameter of the whole intake to be smaller in diameter then the stock intake, K&N is 65mm while stock is 70mm, it's a dirty trick to reduce the need for a tune at the cost of less air. As you will see from these graphs, the trick does work though, since it didn't lean out as badly as my custom stock sized intake did.

 

 

Timing

Looks like timing stayed about the same, this is probably because my timing map doesn't change drastically between 2.20-2.70g/s. More on this in Engine Load section.

http://legacygt.com/forums/attachment.php?attachmentid=254738&stc=1&d=1504036515

http://legacygt.com/forums/attachment.php?attachmentid=254740&stc=1&d=1504036515

 

Airflow

From these two graphs you can see that K&N intake is running less MAF voltage, which calculates to less mass airflow, which calculates less Engine load and ECU runs less fuel and more timing (based on the Fuel and Timing maps). This is why all intakes need a retune.

http://legacygt.com/forums/attachment.php?attachmentid=254736&stc=1&d=1504036515

http://legacygt.com/forums/attachment.php?attachmentid=254737&stc=1&d=1504036515

 

Engine Load

As mentioned int he airflow, less calculated airflow = less calculated engine load. This part is what determines what column you will use for fuel and timing. With less calculated engine load the ECU puts you in a column that's meant for less boost, which means you run less fuel and more timing.

http://legacygt.com/forums/attachment.php?attachmentid=254732&stc=1&d=1504036515

 

Now you probably noticed from the traces that I'm running in the same columns, don't let that deceive you! Since we have a limited amount of rows and columns on a map, we have to use big load ranges and let the ECU interpolate (calculate) between our columns. This is why it's important to look at graphs too, and not just map traces.

 

Wastegate Duty Cycles

K&N is actually running less wastegate duty cycles, even though it was overboosting. This is probably Turbo Dynamics at work trying to reduce overboosting.

http://legacygt.com/forums/attachment.php?attachmentid=254741&stc=1&d=1504036515

 

 

Learning Views

Finally the ECU Learning views, these show the learned airflow adjustments and learned timing adjustments

 

Stock Intake:

http://legacygt.com/forums/attachment.php?attachmentid=254735&stc=1&d=1504036515

 

K&N Typhoon:

http://legacygt.com/forums/attachment.php?attachmentid=254742&stc=1&d=1504036762

 

ECU saw a good bit more knock with the K&N Typhoon, this was a colder day (70's F), on a hotter day I bet the knocks count would have been higher.

 

Conclusion

These cars have very sensitive MAF's and ECU's, which makes them very sensitive to any airflow changes, be it intake or exhaust. Even running an aftermarket paper panel filter will mess with your AFR's, and aftermarket high flow filters will be even worse.

 

Moral of the story, either run a stock intake with stock paper media, or get a tune.

 

 

I fined tuned the stock airbox and then the K&N Typhoon intake, testing results can be found in this post.

1937894217_EngineLoad.png.d794569751f4ae1a94090f6673a9bf1c.png

935885730_IntakesAFR-PSI_StockvsKampNTyphoon.thumb.png.7252f9e32a2336d0d997d699a2da7498.png

LV_StockIntake.jpg.284a569fd225823e11222bb20e0329a1.jpg

1124895715_MAFVoltage.png.7ac2a62f8f6b217b5ef7c157b3aa8ac6.png

414658683_MassAirflow.png.2fae3a16df7247e4917200892af36a5a.png

Timing.png.d2cf31d81dd6f00e7e30165ea54ad300.png

1010330151_Trace-AFR.png.6cf8ea61df4292b90159563744572c74.png

1003887371_Trace-TotalTiming.png.a4be72ac1cb60626497e9ba925d9549c.png

WGDC.png.19ba9b006bd1bf043f5fc847912d5fa3.png

LV_KNTyphoon.jpg.07ce61cdf415d8137d5f50c6ac20bc63.jpg

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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  • 1 year later...

I've seen posts all over the place claiming that you don't need a retune for a drop in filter like a K&N one. This got me curious, How does a drop in K&N filter effect our cars?

 

My 25k miles 05 style filter was due for a replacement so I started comparing them.

 

Left to right: ~25k mile 05/06 Filter: 16546AA10A, ~10k mile 07+ filter: 16546AA12A, ~15k mile K&N Filter: 33-2304

http://legacygt.com/forums/attachment.php?attachmentid=252699&stc=1&d=1500431800

http://legacygt.com/forums/attachment.php?attachmentid=252700&stc=1&d=1500431800

 

As you can probably see, the newly designed filer (16546AA12A) has less pleats and should less restrictive then the 2005 style filter (16546AA10A).

 

Onto testing...

I tested all 3 filters within a 40 minute window, but that still wasn't quick enough to keep the temps 100% the same.

 

Here are the ambient and intake temps for each filter's run:

16546AA10A - Ambient: 91*F - IAT's: 100-99*F

K&N Filter: 33-2304 - Ambient: 89*F - IAT's: 99-97*F

16546AA12A - Ambient: 86* - IAT's: 95-93*F

 

First thing's first is the MAF voltage, which of course determines the Mass Airflow (g/s).

http://legacygt.com/forums/attachment.php?attachmentid=252703&stc=1&d=1500431800

 

MAF Voltage for the K&N drop in filter is less then the two stock filters, this is the same trend that I saw with the CAI's and WAI's. K&N filter dropped the MAF voltages by about 4.3%, this is really odd since the diameter of the MAF housing didn't change.

 

Since MAF voltage fell, ECU's calculated Mass Airflow (g/s) also fell, with lower mass airflow, our calculated Engine Load (g/rev) is also less. This leads the car to run in cells meant for less boost, which means more timing and less fuel with same amount of boost.

http://legacygt.com/forums/attachment.php?attachmentid=252701&stc=1&d=1500431800

 

Notice that even the newer style OEM filter was showing less engine load, I love how better flowing intakes read as less airflow with our MAF's.

 

Timing graph shows that K&N filter ran 1* of timing more, which is not all that bad, but can be more or less depending on your tune.

http://legacygt.com/forums/attachment.php?attachmentid=252702&stc=1&d=1500431800

 

Now the part that really matters, air to fuel ratios. K&N Filter leaned out the air to fuel ratios by by half a point. It went from safe 11.1's to not so safe 11.6's. Even the new style filter leaned it out into what's considered danger zones for our motors.

http://legacygt.com/forums/attachment.php?attachmentid=252696&stc=1&d=1500429926

 

Finally here is those logs graphed in virtual dyno. This is finally showing the gains of the newer filter and the K&N filter. I'm sure the gains would be less if I had the old style filter that was less dirty. Do notice the K&N filter was faster spooling (thought this might be from starting a log from slightly lower RPM, I will verify this).

http://legacygt.com/forums/attachment.php?attachmentid=252704&stc=1&d=1500431800

 

Conclusion

Drop in aftermarket filter does in fact need a retune and will make you lean out. Weather or not it's gonna be in dangerous levels depends on how fine tuned your car is. If your on a stock or off the shelf map, it's probably filthy rich so leaning it out a little might actually be beneficial.

 

I still would suggest tuning the MAF scales for the aftermarket filter, for me the K&N filter wanted a 5% increase to the whole MAF scale, that got my AFR's back to the safety zone.

AFR.png.c1a5f40ce98d2a59eb6256bbae9a66a6.png

950692105_DropInfilters-05vs07vsKNFront.thumb.jpg.6e348be6d36b10fae1489e0e29f9686a.jpg

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1760921038_IgnitionTiming.png.76c1ec6564d5bad978fe2a2786af9d4f.png

2141426729_MAFVoltageandMassAirflow.thumb.png.de596aa28ef35bb118db81421cb7c202.png

436578301_DropInFilterDynos.thumb.png.85506fd415f789d0fe96cfac7077455c.png

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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Funny thing is I got to know one of my neighbors. He has a 2008 LGT. He bought it new and installed on day 1 a typhoon type K&N filter. I asked him if he got a tune for it. He did not. He now has probably 150k+ miles on the car and apparently never had any engine issues :confused:.

In any case, I told him that he should definitely tune for it despite the fact he never had any issue. I will go see him soon and use my btssm app to pull an LV from his ECU. Very curious to see his learned fuel trims.

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If he's stock, then he's probably fine, in fact it probably increased his power and gas mileage since he's not as rich now. My stock tune's AFR's were low to mid 10's, based on my graphs above, at worst he would be at 11.2 AFR, which is still safe.

 

This really becomes an issue with more fine tuned cars, but I'm sure there are plenty of people with more or less fine e-tuned cars that think that "a filter change can't do any damage".

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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I haven't run any simulations myself, but I'd guess that the different filters/environments are significantly changing the average velocity of the air traveling through the MAF channel, which will change just how much air the MAF sensor meters. I'd imagine that with your custom intake, the larger filter area considerably slows down the air flowing through the MAF sensor channel, which will register as a lower total airflow.
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At the end of the day, couldn't we relocate that maf sensor between the throttle body and the intercooler, and retune accordingly? I would think it'd simplify lots of things no?

 

I mean, I understand that the airflow must be significantly different right due to the turbo. But still, I would just think it'd simplify things in general when one decides to change the air intake filter, or air intake tube, or whatever.

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I haven't run any simulations myself, but I'd guess that the different filters/environments are significantly changing the average velocity of the air traveling through the MAF channel, which will change just how much air the MAF sensor meters. I'd imagine that with your custom intake, the larger filter area considerably slows down the air flowing through the MAF sensor channel, which will register as a lower total airflow.

 

Say an aftermarket intake will flow better, which turn translates to less vaccum pre turbo. I would think that an intake that has less vacuum, would be able to flow more, which in turn cools the MAF wire more (which would increase MAF voltage)

 

At the end of the day, couldn't we relocate that maf sensor between the throttle body and the intercooler, and retune accordingly? I would think it'd simplify lots of things no?

 

That's called blow through, we actually run it quite a bit in Nissan world, it's the only way to have a venting blow off valve and not have rich conditions on shifting. Another cool benefit is, you could have a blown coupler and you could still limp the car home, while draw through will start stalling on you.

 

One drawback, as you mentioned, is oil contamination, it will kill your MAF over time, and Nissan MAF's are not as sensitive as Subaru ones. Another issue is, most MAF's are not built for positive pressure, so they will leak, or worse rip the wire.

 

Another drawback is bends, you want to have around a foot of straightaways to calm the flow before it hits the maf. Last drawback is not being able to use velocity stacks right before the MAF, which in my experience really help increase MAF's reading accuracy.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Say an aftermarket intake will flow better, which turn translates to less vaccum pre turbo. I would think that an intake that has less vacuum, would be able to flow more, which in turn cools the MAF wire more (which would increase MAF voltage)

 

I follow your logic, but I'm not sure I was clear on what I meant. Even an intake that flows more could perturb the flow of air through the MAF sensor channel (due to how turbulent the air is through the rest of the MAF housing and velocity stacks). The velocity of the air flowing through the channel that holds the MAF wires could be quite a bit different than the average velocity of the air that just goes straight through the rest of the MAF housing. IMO, The only real way to compare different intake designs for this is to run some FEM fluid simulations, since even a small shift in the geometry could significantly change the results. GrimmSpeed showed some of this stuff in their thread talking about how they designed their intake.

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The velocity of the air flowing through the channel that holds the MAF wires could be quite a bit different than the average velocity of the air that just goes straight through the rest of the MAF housing.

 

You know that might be the key difference, the MAF wires on Subaru maf's are hidden behind a 90* turn. While the MAF wires on my older Nissan MAFs are directly exposed in the flow stream.

 

With our older (Pre 2000) Nissan MAF's the intakes didn't make that big of a tune difference, they might slightly lean it out (due to more air) but loads would stay about the same. I don't recall the load becoming less basically, but I'm gonna see if I can dig up some of my old logs where I tested the stock airbox vs diy intakes when my nissan was still NA.

 

 

I think the biggest takeway with our MAFs is, Yes the car will run leaner from intake/high flow drop in filter, but not because it's flowing more air. It's because the ECU plops it into columns meant for less airflow, thus it has less fuel enrichment set in the map.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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You know that might be the key difference, the MAF wires on Subaru maf's are hidden behind a 90* turn. While the MAF wires on my older Nissan MAFs are directly exposed in the flow stream.

 

With our older (Pre 2000) Nissan MAF's the intakes didn't make that big of a tune difference, they might slightly lean it out (due to more air) but loads would stay about the same. I don't recall the load becoming less basically, but I'm gonna see if I can dig up some of my old logs where I tested the stock airbox vs diy intakes when my nissan was still NA.

 

 

I think the biggest takeway with our MAFs is, Yes the car will run leaner from intake/high flow drop in filter, but not because it's flowing more air. It's because the ECU plops it into columns meant for less airflow, thus it has less fuel enrichment set in the map.

 

Read your thread (I read all of them) took out my K&N and replaced with OEM until tune time.

 

I dont actually load my Tunes back to my car but I practice augmenting the various tables/parameters in hopes of one day trusting myself enough to tune my own car.

 

I never feared that on my 2.5i its fairly bomb proof the GT is like ready and waiting to die due to a slightly faulty table value.

 

Thanks for the research and post

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So really in the end, if someone puts an aftermarket panel filter in their GT/OBXT and keeps it on the stock tune, he/she most likely will be just fine then, due to the simple fact that the stock tune is overly rich. You agree OP?
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Read your thread (I read all of them) took out my K&N and replaced with OEM until tune time.

 

I dont actually load my Tunes back to my car but I practice augmenting the various tables/parameters in hopes of one day trusting myself enough to tune my own car.

 

I never feared that on my 2.5i its fairly bomb proof the GT is like ready and waiting to die due to a slightly faulty table value.

 

Thanks for the research and post

 

Thanks brother, I appreciate it :)

 

So really in the end, if someone puts an aftermarket panel filter in their GT/OBXT and keeps it on the stock tune, he/she most likely will be just fine then, due to the simple fact that the stock tune is overly rich. You agree OP?

 

From what I've seen with factory air to fuel ratios, I think that's a fair assessment. 5% reduction in engine load shouldn't run too much more timing then before either.

 

Having said that, I didn't have my wideband when I was bone stock, nor did I have it when I was stage 1 and Up Pipe. Only when I got an aftermarket downpipe with a WBO2 bung, did I finally hook up my AEM UEGO. When I went with a Stage 2 downpipe I kept the boost same as stock, which should hopefully mean my engine load was the same too. I saw AFR's in mid 10's all the time.

 

I just can't say with 100% confidence that a bone stock car will be fine, because I didn't use a more accurate (than factory) wideband until I was already fairly modded.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Dug up some logs from my NA SR20DE Infiniti, where I tested stock airbox vs WAI with flowstack.

 

First is the MAF Voltage and Engine Load (TP, Nissan's version of g/rev)

http://legacygt.com/forums/attachment.php?attachmentid=252795&stc=1&d=1500608961

 

Next is AFR and Ignition timing

http://legacygt.com/forums/attachment.php?attachmentid=252794&stc=1&d=1500608961

 

As you can see, MAF Voltage, Engine Load, and Ignition timing stayed the same, the only thing that changed was AFR's (which is expected from a better flowing setup).

476427161_SR20DE_StockAirboxvsWAI-AFRandIGN.thumb.png.d8c6a9e18e8ea092896fe2da213fc551.png

1947389133_SR20DE_StockAirboxvsWAI-MAFVoltandEngineLoad.thumb.png.d99c14d669054fc136d88659911dcdcf.png

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Quick update, MAF scale adjustment difference between the newer style OEM filter (16546AA12A) and the K&N Filter needs 2% more MAF scale. Basically the K&N filter is 2% leaner then the newer style OEM filter, while almost 5% leaner then the older style OEM filter.

 

Which means if your car came with the newer style filter, K&N filter is a lot more drop in friendly without a tune.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 2 months later...
Funny thing is I got to know one of my neighbors. He has a 2008 LGT. He bought it new and installed on day 1 a typhoon type K&N filter. I asked him if he got a tune for it. He did not. He now has probably 150k+ miles on the car and apparently never had any engine issues :confused:.

In any case, I told him that he should definitely tune for it despite the fact he never had any issue. I will go see him soon and use my btssm app to pull an LV from his ECU. Very curious to see his learned fuel trims.

 

 

I finally had a chance to pull an LV from his ECU. And yep, low and behold most of the fuel trims were almost pegged at +15%, except the idle trim. The 'WOT' trim was at 14.5%. But he almost had zero FLKC events, just one at somewhat low load and IAM was at 1.

Now I understand that it is just a snapshot in time. I would love to drive his car for a bit and see how the trims behave and stuff.

 

In any case, I showed this to him, explained what that meant, etc.. He is now planning to reinstall his stock intake box, since he has no intent in tuning the car. :).

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