In theory yes, but added it because I am tired of the noise and smell.

I run the same CAT on my GTR, but with a 4" dump prior to the CAT, which I have posted a picture below. I control the boost actuated dump with a Mac Valve so it can be turned on or off with a switch. Additionally, I have a Hobbs Switch in series with the Mac Valve so when I turn it on it doesn't actually open until ~12psi.

https://cimg2.ibsrv.net/gimg/www.evo...e3817150ad.jpg
https://cimg6.ibsrv.net/gimg/www.evo...6429679971.jpg


I ran it on the dyno with the Valve Open (bypasses the CAT) and with the valve closed (through the CAT and out the exhaust). The result on the HP at the top end was less than 10hp loss when the car is making ~700hp@wheels. I did get an improvement in torque on the initial hit, but didn't lose much on the top end. With the EVO likely being down at least 150hp@wheels vs my GTR I don't think I will have an issue with power loss. Red is valve open (bypass CAT) and Blue is valve closed (through the CAT and out the exhaust).
https://cimg1.ibsrv.net/gimg/www.evo...0e0afdf083.jpg

I've seen a gutted cat cause more power loss than a cat. Lol

Started the day by draining the oil at ~150 miles and replacing with another round of VR1 10W-30 conventional for the next ~350 miles before converting the Mobile 1 "FS" 0W-40 Synthetic. Drain plug magnet looked good and cutting open the filter revealed random specs of silver, which are the rings so I expect this until about 500 miles so so far so good.

I had removed the factory O2 sensor right off the turbo and placed my Bosch LSU 4.2 there, but after reading they don't like extreme heat I moved it back below the car right behind the engine. I have the PLX running the wideband to the rear O2 input and the narrowband output of the PLX to the front O2 input. I went ahead and stuck the stock (dead) O2 sensor back in the front just so I would have another unused connector.

Next step was to turn my lift around in preparation for adding the CAT and Varex muffler. The days of doing exhaust on my back are over!


https://cimg8.ibsrv.net/gimg/www.evo...7b2fde1120.jpg

I have the same arrangement on my Evo where my wideband is located about 1.5-2 foot from the start of the DP and feeds a simulated NBO2 signal to the ECU. The extra distance from the engine does somewhat affect the O2 feedback correction responsiveness. I've thought about putting the wideband in the stock O2 location to see how long it lasts.

Love how you still giving Evo attention even after the Gtr! What lift are you using?

Didn't buy it here, but same one.....
https://www.bestbuyautoequipment.com...l-6k-mr-38.htm

The GTR is full time closed loop (except in limp mode) with the widebands (Nissan Denso 211200-7100, but some people use DENSO 234-9071 as non factory replacement) right off the turbo, but not old school LSU 4.# sensors. I ran the old sensor in the current location (below the car) since 2011 and never had an issue using it for tuning so not too concerned about a 100ms delay.

I was actually thinking about you and wanted to get your thoughts. My GTR uses the Hitachi MAF sensors (pre turbo in stock form) and it stock form will support ~350hp/per in a 3" tube. Therefore, thinking in stock form they can support perhaps 600hp in a 4" tube (need to do actual calculations). I had mine recalibrated so they support ~450hp/per in a 2.75" tube (currently running as blow through after the BOV). Anyway, they are 5 wire and use a 12V power source, output a 0-5V MAF signal (coorelating to grams/s and I have the tables), and a 0-5V output for temperature (I have the tables).

My EVO is on SD, but I would love to be able to run a single MAF on the EVO for ease of tuning and accurately measuring air density. Is this something that interests you or something that can be done in ECU Flash?

Are the calibrations for preconfigured maf sensors allotted different resolution than maf tables you program in haltech?

Not sure I understand the question and I only ran SD with the Haltech. I pulled the Haltech last year and put it in a box because I got tired of swapping in the stock ECU every year and changes a bunch of things to pass inspection. Since then I am running SD using V5 Tephra 2D with ECU Flash.

The Magnaflow muffler was way to big for under the car so just added the CAT for now. Made good progress, but still another 3-5hrs of work as I want to raise a portion of the back section.

Old Setup is 3.5" 18g 321ss with Magnaflow muffler
https://cimg5.ibsrv.net/gimg/www.evo...e45d55be03.jpg


Adding the CAT just after the 3.5" vband clamp
https://cimg2.ibsrv.net/gimg/www.evo...ded8fb48b7.jpg


Adding the bellow just after the CAT.
https://cimg5.ibsrv.net/gimg/www.evo...6b737bdce5.jpg

Oh yea, I welded below the car.

https://cimg6.ibsrv.net/gimg/www.evo...3c9fb1597f.jpg


Integrating it back into the old exhaust. I was off in my measurements by ~0.5", hence the 0.5" spacer I had to add. Doh, another 30 minutes of work.
https://cimg1.ibsrv.net/gimg/www.evo...60377961e6.jpg


I use Solar Flux B instead of purging and it is very effective. It is the grayish tan powder on the inside of the pipe and circled in red. Circled in Blue is an area that I realize I can tuck up much better so gonna go back and redo this section. It tucked up nicely to the sway bar so that portion is good.
https://cimg1.ibsrv.net/gimg/www.evo...61f0cefe06.jpg



Bosch LSU4.2 wideband about 9:30 on the pipe. Wow, now I remember how much of a PIA it was to make my midpipe. Gonna have to do some of that in the rear as well to tuck the pipe up higher. I have mandrel bends, but sometimes easier to pie cut those directional changes.
https://cimg5.ibsrv.net/gimg/www.evo...b77b298609.jpg

CAT is officially in the system.
https://cimg0.ibsrv.net/gimg/www.evo...f24cf5cbd4.jpg

A blow-through hot wire MAF wouldn't be any harder to do than setting up a MAP sensor for SD. Where/how do you have these MAF sensors calibrated?

Thank you for the response....PM Sent.

BTW, I've been starting to read up on how you tune the EVO with MAF, but have yet to find a definitive post showing step by step.

For the GTR I have essentially two tables that I care about for tuning fuel. I have the "Fuel - High Det" map, which is the targeted AFRs (GTR is full time closed loop). This table is RPM vs Theoretical PW as the GTR use TPW for load. I also have two "MAF Calibration #" tables, which are just left and right MAF. This table is 2D and is MAF voltage vs Mass Air Flow (g/sec). Once you define your targeted AFRs you then drive the car and log MAF Voltage and STFT. Using log viewer I plot these (x axis MAF Voltage & y axis STFT) and then look at each MAF voltage and see the corresponding STFT. If my STFT is 110% at 4V then I go into my MAF table and increase the (g/sec) value by 10%. There is also a VE table that is used a part of the ECU calculations, but it is never modified.

From my reading thus far is this essentially how you tune the EVO with MAF?

I'm sure all the tuners out there have their own recipe. Mine is probably the most in-depth, or perhaps to put it another way, the most overkill. And its probably better to call it calibrating than it is tuning. For me, tuning is setting timing, AFR, MIVEC, boost to optimum values. That's all fairly straightforward. Calibrating is what's needed to get the car to follow the timing, AFR, MIVEC, and boost requests. And the only aspect of the Evo ECU that really needs to be calibrated is fuel. People like to think that a MAF is a direct measure of air flow, and I suppose it does tell you how much air passed through it, but the problem is that all the air does not necessarily end up in the cylinders. Just like with SD, changes to cams, exhaust, turbo that affect pass through or reversion will all affect how much of the air makes it into the motor. And of course with MAF cars, changing the intake can affect the MAF scaling. So the bottom line is than tuning a MAF Evo isn't much different that tuning an SD Evo - the first step is to sort out the fuel calibration.

Up until maybe 5 years ago, most people didn't pay much attention to the injector linearization calibration (not the flow rate and dead time but the partial pulse linearization values). That calibration has a big effect on off-boost drivability especially with big injectors or when changing to a high-Z injector that can have much different linearization values than stock injectors or some low-Z injector. The linearization values provided by the aftermarket injector suppliers are a good start, but for best drivability, the values usually need some tweaking. The other big part of the fuel calibration, probably bigger than the injector settings, is the MAF scaling. What everyone calls the MAF scaling is actually a fuel flow rate vs MAF signal scaling. There is a true MAF scaling, but its a single multiplier that no one every touches. Anyhow, the stock MAF scaling (as everyone calls it, and I'll use the term here) is off by miles for a highly modified Evo. It needs a lot of work to make AFRs correct (match target values in the fuel table) both in boost and out of boost. Its pretty easy to dial in the in-boost scaling. The hard part is off-boost. It requires a lot of time to dial in. Most people don't realize how much the STFT and MTFT are making up for bad MAF scaling values during off-boost. Dialing in the off-boost makes the car drive much better. It took me maybe 5 tanks of driving around off-boost to get mine dialed in. It requires spending a lot of time gathering STFT, MTFT, LTFT, and AFR data at different MAF Hz readings. Anyhow, no point in describing it in gory detail here. I think I posted my method somewhere here, and if not, I can send you a copy.

Definitely love to have a copy and I assume you are referencing the injector latency when you say injector linearization. I do understand your differentiation of tuning vs calibrating and that is the biggest issue, not real clear as to the relationship of all the tables as it relates to fueling. Is there a formula you have developed that shows the algorithm used for final fueling? For the GTR, COBB was nice enough to have the MAF Calibration A/B tables that are a 1:1 relationship (raise g/sec 10% and you get a 10% increase in fuel) with fueling although there are other tables that can be accessed that influence those calculations.

BTW, I sent you a PM regarding the Ford Hz based MAF sensors so wanted to get your thoughts.

I think your PM bounced because my mailbox was full. Try again. Include your email.

Not sure how easy it would be to adapt another frequency-based MAF sensor. I know that there were some kits along time ago, but I'm not sure how well they worked. I believe there was a converter box.