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Discussion Starter · #1 ·
Has anyone cut out the choke at the MAF yet? Here is my theory.
Cold air enters, it is suppressed to 2/3 of the tube then the tube is bigger then goes into a smaller tb of my case a 90mm tb and adapter.
Is that not choking the cold air to allow only the amount at the hotspot not to allow expansion at the TB?
I mean that is how jet engines work , they dont choke the cold air before the mix.

Anyway I cut that mass of crap out. Didnt run/ Or Rev. Hahaha.
But I got Pro tuner, I tuned out that and in 10 mins got solid idle .8 ft and cruise 3-4 ft.
That was about 30 mins workout. Tomorrow I will finish the matrix and report.
Oh, and side effect. I dont have to tap throttle on cold startup, it rummm, idle. :)
 

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yes its been done. did you search? Jauntybishop aka milenkogt did it i believe.
 

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Apparently he didn't search... This was done when the kit first came out years ago. You cannot remove the MAF reducer and expect the truck to run without a MAF scaling compensation prior. But atleast you fixed the issue. Not sure what " .8ft and cruise 3-4ft" means..

You change MAF scale and set AFR tables in fuel compensation to 100, change MAF voltages and go from there. Fuel compensation is the last reference UPREV should look at and is for fine tuning. Anything over 100 is increasing fuel, anything under 100 is decreasing fuel.

The airaid tube is designed that way with a taper because of a venturi effect. Larger to smaller taper increases velocity.

The reason the MAF reducer is there is because the sensor is calibrated to read a 3'' diameter tube vs a 4.8" ID which is what the tube is once the reducer is cut out and you measure from the inside of the slot flange opening to the bottom of the tube floor.

JOSH19K was the first person to do this mod back in like 2013 if I recall, he even made the base map for his truck. (same person who's tuned my truck for years and has taught me)
The problem I had when I removed the maf reducer is the idle searching or wanting to stall under deceleration off throttle at random. This was from oncoming air turbulence over the MAF sensor.

When I installed the 5'' Mishimoto CAI setup (custom) it came with air straighteners in the MAF housing to direct air across the maf sensor more evenly, thus reducing or eliminating turbulence over the sensor.

The truck with 90mm TB, MGT90 90mm inlet and big a$$ 5'' mishimoto intake drives like stock when i first bought it, but with added response and power.

The incoming air charge is moving so fast, doubtful there are going to be hotspots. Plus its plastic and the intake manifold is Nylon 55 composite.

You're IAT sensors is built into the MAF sensor and its exposed to heat soak.

Best thing you can do is ram air mod, which you'd have to search for and it pulls air from behind driver side of grill area.


I'm doing an intake manifold project soon to help with heat soak and i'will post up my data.

So in summary, don't ever cut the MAF reducer out of the MXP airaid tube unless you already have Uprev Tuner software and know what you're doing OR you have the supplied MAF scale to start with prior to removing reducer. Also, VENT THE ENGINE BAY... get rid of heat.

Other than that, all this stuff has been tested and thought of over the years. But it is really cool to see people still posting and showing interest in projects like this again. KEEP IT UP!
 

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Lol by the way on how jet engines work, I understand what you're saying, but the intake tube doesn't have an assortment of Impeller/compressor blades as well as fuel being dumped into the tube.

Plus the engine is probably only pulling in around 600 CFM ish at full song.

Also GM/S is useless as a comparison now because you've changed the maf scaling. Nissan silly way of avoiding using CFM... like "BURN TIME"... why...
 

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Discussion Starter · #5 · (Edited)
Thanks for the input you gave me, it means alot. I did search with no luck :(
So they say , you learn from your mistakes , hehe.
I would love to see the MAF scale table that was made after doing what I already did. I am having trouble dialing anything over 30% Throttle and with the 90mm TB it makes it all that much rockier :)
I did take your advise and 0 out the fuel table to 100% to get a true MAF to trim reading and also dropped my max AFR to 11% until I get it right so I dont melt a valve into Japanese goo
 

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I haven't even looked at Uprev Tuner in over a month. There for a while I was balls deep into learning about it all, but other priorities took place.

My truck is flex fuel, so I also scaled the MAF table and fuel compensation table to zero out the ethanol mix ratio. Don't want to have to fight with the ECU trying to take over.

If you have time or even a passenger, take your laptop and have someone ride with you while you do the live tuning datalogging with the tuner and watch log the tracers on your fuel compensation table.

I spent a lot of time adjusting MAF voltages in small increments to rid the engine of what I thought was a lot of knock lol, Well it wasn't much at all so i was chasing my tail for a few days.

Then... I installed those new 370Z 380cc fuel injectors out of a VQ37VHR which were flow tested and cleaned and had 1% variance between all 8. That made a HUGE difference overall in the way the truck started initially as well as hitting my fuel targets.

Its kind of crazy, but I haven't tuned the truck since the injector install because after reviewing my logs the truck is doing what its supposed too. Plus the start up time freaks me out time to time, as in you bump the key and it fires off immediately. Not the typical, turn turn turn fire, or even turn turn fire. Its like the crank rotates maybe 180 degrees and bam.

Not sure if injector latency, different K-Fuel multiplier, etc... but I don't really want to mess with it much anymore until I get the cams installed lol.
 
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