MAF calibrations for bigger intakes

[CamSpeed360]

Originally Posted by Lex If the readings are turbulent/fluctuate. Look closely at MAF voltage since that's the root of the measurement

Noted. Thank you.

[Lex]

Originally Posted by CamSpeed360 So you're suggesting an air straighter? Everything else is sealed. Or was. My car is stocked out at the moment.

@CamSpeed360; Did you reinstall the intake? Any issues?

[CamSpeed360]

Originally Posted by Lex @CamSpeed360; Did you reinstall the intake? Any issues?

Yes sir, just the other day. Everything is running great. I need to do a maf cal but my LTFTs are within 4 while driving. At idle my LTFT is +20 so I need to adjust it there. It may have something to do with my catch can. But its running well for the most part. Maf cal, downpipe and then its toonin time!

[Lex]

Originally Posted by CamSpeed360 Yes sir, just the other day. Everything is running great. I need to do a maf cal but my LTFTs are within 4 while driving. At idle my LTFT is +20 so I need to adjust it there. It may have something to do with my catch can. But its running well for the most part. Maf cal, downpipe and then its toonin time!

Awesome glad to hear it's resolved and it sounds like the MAF cal won't be too difficult.

[kentwat]

Lex I was thinking of getting the 3" HTP intake would I use the same values as the Sure 3"? Thanks for your support on the calculations. Kent

[GODspeed7]

Originally Posted by kentwat Lex I was thinking of getting the 3" HTP intake would I use the same values as the Sure 3"? Thanks for your support on the calculations. Kent

Just ordered mine as well today. Anyone care to provide info on this?


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[rfinkle2]

Originally Posted by GODspeed7 Just ordered mine as well today. Anyone care to provide info on this? Tapatalk LIKE A BOSS!

LOL. I'll send you a map with a 3" maf curve.

[Lex]

Remember that the MAF calibration is mostly affected of the inner diameter of the MAF housing. SURE's housing is pretty darn close to 3". If the HTP is pretty close the MAF curve will work just fine. Things like the air filter will play a role but that is relatively minor and mostly seen at idle.

Also, don't be afraid of LTFTs. As long as they are less than +/-10% you're fine, especially if those larger numbers are at idle and low throttle. The LTFTs are the car's way of adapting to the environment and that's why they are there. Once the LTFTs are learned they are applied immediately to the MAF calculation. In other words, the car calibrates the MAF for you (within reason) using the LTFTs.

[CamSpeed360]

So are you saying that you can hit your targeted AFR after your car has learned its LTFT? I understand LTFT is for closed loop and when you're wide open you are in open loop. That's why the importance of a maf cal kinda confuses me. Do we calibrate our maf so that we don't have to worry fuel trims right after a new map flash?

I mean, my shit's pretty well calibrated now but I still don't have 100% understanding.

[Lex]

Originally Posted by CamSpeed360 So are you saying that you can hit your targeted AFR after your car has learned its LTFT? I understand LTFT is for closed loop and when you're wide open you are in open loop. That's why the importance of a maf cal kinda confuses me. Do we calibrate our maf so that we don't have to worry fuel trims right after a new map flash? I mean, my shit's pretty well calibrated now but I still don't have 100% understanding.

Long term fuel trims are the ECUs way of scaling the MAF. So if your MAF is off 10% in a certain region and the ECU uses STFTs to adjust for this, eventually the LTFT will be set to 10%. That is equivalent to the MAF being scaled correctly in that area now since the final fueling calculation automatically includes the LTFT value.

STFTs are always active in closed loop and they help bring AFRs on target based on feedback from the O2 sensor. Eventually LTFTs are learned making the deviations from target AFR smaller and STFTs which rely on the O2 feedback become smaller. This means the car reaches target AFRs even faster.

In open loop STFTs and LTFTs are not active.

On the gen2 there are open loop WOT trims similar to STFTs that help the car target AFRs. We can't log these but the MAF can be 10% off and the car will track AFR targets perfectly fine. These WOT trims have a range of +/- 10-12% from what I've seen.

On gen1 cars there are some WOT trims but they take a lot longer to learn so in gen1 cars it is more important for the MAF cal to be closer to actual than in gen2 cars and fuel variations affect it more. However in gen1 cars there are also some trims that act at WOT and after enough WOT runs the car starts to track AFRs even better.

So what is the lesson here?

The MAF cal should be within +/- 10% in closed loop and I would say +/-5% in open loop. I would not strive for a perfect calibration because the weather, motor aging, gas used, A/C being on will change STFTs and LTFTs. The car does not run any "better" if the LTFTs are 1% versus 7%.

The learning mechanisms of the ECU are in place to allow for these variances in he MAF cal and adjust all the time. It's a smart machine

[CamSpeed360]

Well that makes it easier to wrap my head around. That was kinda what I was thinking but your explanation makes it much more simple. Thanks!

[JDW1]

Just to be clear, these calibrations should be a good starting point for bigger turbo's also? Would it be prudent to decrease boost while dialing in wot afr's?

[Lex]

Originally Posted by JDW1 Just to be clear, these calibrations should be a good starting point for bigger turbo's also? Would it be prudent to decrease boost while dialing in wot afr's?

The MAF will read the same regardless of what turbo sits behind it. Also when making any map changes you should ease into the throttle and watch the vitals: Boost, AFR, Fuel Pressure, KR before stomping through a full high gear pull.

Also be aware that a larger turbo will flow more air so it will place the sensor reading into an area of the MAF curve that was not used previously. What I find is that if the curve is reasonable (not hacked up) a curve that matches the intake at low airflow levels will also match it at higher airflow levels.

[Voltwings]

^^ this. Going from my 3" intake, after scaling my MAF and then just 2 maf cals (was trying to be safe and rich but wwaayy over shot it) i was running just as close to target AFR with my 4". Granted going from a 3" to 4" i dropped a ton of MAF voltage so that was already a frequently traveled area that was well dialed in. Hell even now im barely touching 4.0v at 25 psi haha.

[JDW1]

For me the HTP values are pretty close, I was pretty rich at WOT in the upper RMP but I was ok with that. I know there's a lot of factors in place to get it dialed in for each car but it was a great starting point, thanks @Lex;

[Lex]

From what I've read the HTP has a smaller ID than 3." Can someone measure the MAF ID and post it here for the HTP and I can make a better MAF cal.

[JDW1]

Inside diameter looks like 2.75"

[DamagedGoods]

Sigh I was hoping it was an honest 3"


Tappin

[Lex]

Originally Posted by JDW1 Inside diameter looks like 2.75"

I heard 2.8" from someone else. Did you verify this with calipers?

[JDW1]

All I had was a tape measure. 2.8 may be more exact

[GODspeed7]

@Lex; would having the HTP 3" intake actually being 2.8" but scaling for 3" explain my rich condition at WOT?


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[Lex]

Originally Posted by GODspeed7 @Lex; would having the HTP 3" intake actually being 2.8" but scaling for 3" explain my rich condition at WOT? Tapatalk LIKE A BOSS!

Yes sir.

[GODspeed7]

Originally Posted by Lex Yes sir.

Spoke with Matt at HTP and the inner diameter of the intake is 2.87" so take that for what it's worth!


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[Lex]

I am getting a quite a few customers here that have issues with the MAF cals fpr the HTP intakes and I posted in their section. From my calculations the ID of these intakes is somewhere around 2.75." The ID should be measured right where the MAF sensor sits, not where the pipe is bead rolled - so measure further in than the bead rolled section.

For you guys that have them can you please measure the ID with some calipers? I want to settle this and get some MAF cals out for people to use and stop the confusion. A MAF cal for a 3" ID MAF won't work well at all for a 2.75" ID MAF.

[Deldran]

Originally Posted by Lex I am getting a quite a few customers here that have issues with the MAF cals fpr the HTP intakes and I posted in their section. From my calculations the ID of these intakes is somewhere around 2.75." The ID should be measured right where the MAF sensor sits, not where the pipe is bead rolled - so measure further in than the bead rolled section. For you guys that have them can you please measure the ID with some calipers? I want to settle this and get some MAF cals out for people to use and stop the confusion. A MAF cal for a 3" ID MAF won't work well at all for a 2.75" ID MAF.

I have the 3.5 inch HTP. I was just doing my own maf cal but I think I messed it up again so was going to use ur jbr 3.5 cal and see where it got me.

As far as measuring the ID because of the honeycomb straightner it will be hard to get it.
@HTP; what the ID of the 3.5" intake

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[alfre127]

Gotta say thanks, used CPE 3.25 MAF Cal for My Sure 3.25, Wow AFR almost spot on barley have to do any MAF Cal, Thanks LEX.

[JDW1]

It's looking like for me and the HTP, around a .9 multiplier for the cruising breakpoints, up to 70 and .6 for WOT to get me to my comanded 11.8.

Still in the process of getting it within my tolerancees but that should have it very close.

[Lex]

Originally Posted by JDW1 It's looking like for me and the HTP, around a .9 multiplier for the cruising breakpoints, up to 70 and .6 for WOT to get me to my comanded 11.8. Still in the process of getting it within my tolerancees but that should have it very close.

So you're noticing that it is very rich in the WOT regions correct? I am running into this as well. The MAF curve for these intakes doesn't seem to follow curves for other MAFs which is a little troublesome. The shape of the curves should not change.

[GODspeed7]

@rfinkle2; this is a good thread too. This intake is proving to be a pain in the ass!


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[rfinkle2]

Originally Posted by GODspeed7 @rfinkle2; this is a good thread too. This intake is proving to be a pain in the ass! Tapatalk LIKE A BOSS!

No worries. As long as it is consistent, it is just a matter of making some changes to the curve.

[GODspeed7]

Originally Posted by rfinkle2 No worries. As long as it is consistent, it is just a matter of making some changes to the curve.

You have an email man!


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[rfinkle2]

Originally Posted by Lex So you're noticing that it is very rich in the WOT regions correct? I am running into this as well. The MAF curve for these intakes don't seem to follow curves for other MAFs which is a little troublesome. The shape of the curves should not change.

Yes. I do see the 3" version especially rich @ wot.

I agree in theory. If we can get some sort of consistency, we will post our findings.

[JDW1]

Originally Posted by Lex So you're noticing that it is very rich in the WOT regions correct? I am running into this as well. The MAF curve for these intakes doesn't seem to follow curves for other MAFs which is a little troublesome. The shape of the curves should not change.

I mis typed, it's .96 at WOT not .6 but apparently I'm flowing more air than most at WOT, logged over 380g/s last night(curiously I know). My AFR's in that log were 11.7-11.6 mainly, I scaled back another 1% to get me ~11.8. In my first log with your Sure cal i was at 10.9 AFR by redline, maybe low 11's prior, I've just made my 3rd revision. I've seen LTFT's cruising ~-9 so those break points are definitely spot on for pulling that much.

[Deldran]

@Lex;

I am going to flash your 3.5" curve at lunch today.
Hopefully I can get some miles on and post some initial results of the difference.

I always seem to have trouble calibrating the area of the curve between a 2nd gear maf log and wot. That is where I screwed up last time and the curve had a bump in it so I figured I would start fresh I hope I can help out with this. I do love the 3.5" htp the fitment it great.

What could make it so much different than the jbr other than the built in honeycomb

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[Lex]

Added the HTP 3" BETA calibration to OP. At least it's closer to the truth but not fully developed.

[ledfootrob]

Cheers for this, works well on my car. Idle is fine, C/L is only 3-5% off just gotta do some WOT logs but so far so good. Even managed to fit intake inside the Corksport Airbox, just had to make the hole slightly larger.

Im using the HTP 3" TIP 3" Maf housing and AEM Dry filter.

[Deldran]

@Lex;

So here is some initial stuff, no logs yet waiting to get some more miles.
It appears to be a bit rich at idle. LTFT at idle is -3
Then it appears to be lean at city cruisng aka 40 mph in 5th. LTFT there is 10
Then the couple times i went woot it was also a bit rich. I target 11.8 was getting 11.5-11.7.

Also this call does not like cold starts. Previously on an OTS cal the i modified for this intake i didnt have any issues. This morning i went out to start my car, it started then died a couple seconds after. It did this twice. It threw a CEL but it started on the third try and the CEL was no longer there. I was a bit late for work so i didnt try and check it before I started it for the 3rd time. I gave it a bit of gas and it stayed running.

This is odd to me because I took my previous stock intake cal i had did and just multiplied it by 1.66. This got me started, it spat and sputtered for a bit on first startup but after that never had a cold start issue and it was added almost 20% ad idle.
temps here today are 23 degrees so if it does it again when i go to leave work i will be sure to check the CEL

[Lex]

The 3.5" JBR calibration zeroes out the MAF curve up to 0.9V to avoid a CEL. If the HTP MAF is smaller that section might get into the idle regions and this may be causing the stalling. Take a MAF cal log including idle and a WOT log and I will see if I can come up with an HTP 3.5" cal that works better.

Does your intake have the honeycomb?

[Deldran]

Originally Posted by Lex The 3.5" JBR calibration zeroes out the MAF curve up to 0.9V to avoid a CEL. If the HTP MAF is smaller that section might get into the idle regions and this may be causing the stalling. Take a MAF cal log including idle and a WOT log and I will see if I can come up with an HTP 3.5" cal that works better. Does your intake have the honeycomb?

Yes all of the HTP intakes have a built in honey comb. I will look and see how far up I zero out my old maf. I think it wasn't up to .9

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[sleepyspeed6]

I have a 3.5" intake and if it is under 15°ish it will start and die once then starts fine.