Dual MAF + Skyline R32 ECU technique for dual intakes

[tg]

My tuning guy said, and he is VERY knowledgeable on the subject and has tuned several high HP Z's and skylines, that the absolute best way to go is to get two MAF's (instead of 1 maf and an ecu tune that doubles the signal) and use a modified GTR (89-93) ecu with it as it has dual MAF inputs on it. You basically wire the second maf back to the ECU harness where there are extra pins for it. This eliminates all issues of irregular idle + stalling at highway speeds with the clutch in etc. since the skyline had two maf's (one for each 3 cylinders and turbo) this method works particularly well because you can seperate the two intakes (unlike the 'doolz') and have your ecu manage fuel independantly for both banks of the engine, keeping everything parallel.

Thought i was a good piece of information to share for those looking to push over 500hp and looking for a reliable setup that is even better than the 'dual maf translator' they sell.

The reason for this is that the maf signal is not linearly proportionate to the amount of air coming into it. To explain it further, say you have the stock single MAF setup. With the engine OFF and the key ON, the signal is 1.0V, which means the ECU thinks 0 air is coming in.

Now, say the car is idling and there is 80cfm going into the MAF, which registers only 1.2V, letting the ECU know that its taking in enough air to supply enough fuel for say 800rpm of activity at idle. At redline, the car is taking in 650 cfm of air, the maf will register 5.0V (estimated). This lets the car adjust for the right amount of fuel to supply 350 cylinders per second.

Now, say you have one MAF on one side of the dual intake, and you have an ECU mod to accommodate for that (the map is changed internally, so it will say at 1.1V, supply enough fuel to accommodate for 800rpm and at about 2.5v supply enough for redline [just for example, not definitive]). In theory this technique works well because you are changing the ECU to accommodate, but this technique does two things that are undesirable. Firstly, it doesn't take into account the fact that one side might be taking in more air than the other... un-even filter wear, air disturbance in the front facia at speed (stalling at highway speeds, anyone? ). Secondly, you lose your 'resolution'. Think of resolution as just what it implies, the amount of points a MAF can register between 1.1V and 2.5V is less than between 1.2 and 5.0V. Furthermore, if your MAF isn't in perfect condition, the inaccuracies are DOUBLED with this technique. Say our MAF is burned out slightly, what would have been a slight lean condition before just became twice as bad. There is also the issue that a MAF at 40cfm will likely not register 1.1V instead it will be closer to 1.05 or so, but the ecu is tuned for this so it doesn't matter.

SO, the other alternative thus far has been an adapter that allows you to put two MAF's and connect them both to your ECU along the normal MAF adapter and you don't need to tune your ecu (unless you change your injectors, which everybody who NEEDS to run dual intakes has to). SO this method is superior because it takes the average of the two MAF's and send it to the ECU which fixes the problem of having uneven airflow etc, but this causes another problem. At Idle, your MAF's are only registering 1.05V each, and when sent to the ECU at 1.05V it thinks your car is doing 400rpm instead of 800 or whatever, because it is non-linear, but in general it works better than the aforementioned method. It costs about 280$, and an extra MAF, making it more expensive than the previous method.

Now, the Skyline GTR ECU method solves both these issues because it has two inputs for MAF sensors and takes into account the idle issue and the disambiguation between both sensors. Disadvantage is that you need an R32 ECU (about 140$) and you need to run an extra set of wires to the ecu. The result though is a completely reliable idle and perfect metering up to 1000hp. It is a bit less expensive than the adapter method but requires more work+more knowledge on the matter of wiring and tuning.

I'll let you guys know how it goes next week along with details and some dyno vids!

Modified by tg at 2:38 PM 12/4/2009

Modified by tg at 2:38 PM 12/4/2009
Modified by tg at 2:41 PM 12/4/2009

[tmeyer29]

very very interesting, keep us posted!

[ztommyx]

can we run two MAF w/o the GTR ECU?do we have to tap in the wires to the modified Z ECU?

link us to the write-up. i saw it awhile back. sounds interesting.

here's the dual MAF adapter

[tg]

can we run two MAF w/o the GTR ECU?do we have to tap in the wires to the modified Z ECU?

link us to the write-up. i saw it awhile back. sounds interesting.

here's the dual MAF adapter

I mentionned this in my post, but it also has a drawback.

Either way I'll do my best to write up the process, I haven't found one online yet so I'll just be following my tuner's instruction.

[Ace2cool]

GREAT info, tg. Definitely let us know how it works out.

[ztommyx]

I mentionned this in my post, but it also has a drawback.

Either way I'll do my best to write up the process, I haven't found one online yet so I'll just be following my tuner's instruction.

i know there was a write-up on it. this set-up does not need the skyline ecu.

here's a few pics i took from them as a note and visual.









i have a few more pic but this write up is for DYI. i just lost the bookmark for it.

[tg]

yeah i'm a bit worried bout mine because I use the doolz so it might negate the benefits of having separately measured banks and make one side run rich/lean ;\ We'll see I guess.

[txQ45]

I have modifed dual intake "Doolz" removed the Neo and all the wiring from dual intake and installed the saline

No problems

I also have Nistune (Nistune Dealer) with a 91 TT ECU no need for the Skyline ECU ,,,

[Jim (Selin Design)]

Tg,

It appears you have misunderstood how my dual MAF translator operates as it does not have the idle disadvantage you have described below. For general clarity, the translator adds or averages the corrected flow value, not the signal voltage. The non linearity of the sensors output is mathematically defined in the translators memory allowing the processor to output exactly the right voltage at all times. The translator has no dissadvantage here and provides the same idle improvement and smoothness that you are seeking. Your example of averaged 1.05V signals makes the incorrect assumption that averaging is used with the stock ECU when it is only appropriate for dual intake tuned ECUs. When using the stock ECU, a small switch is thrown to put the unit in flow addition mode, resulting is an output of something more like 1.2-1.5V

SO, the other alternative thus far has been an adapter that allows you to put two MAF's and connect them both to your ECU along the normal MAF adapter and you don't need to tune your ecu (unless you change your injectors, which everybody who NEEDS to run dual intakes has to). SO this method is superior because it takes the average of the two MAF's and send it to the ECU which fixes the problem of having uneven airflow etc, but this causes another problem. At Idle, your MAF's are only registering 1.05V each, and when sent to the ECU at 1.05V it thinks your car is doing 400rpm instead of 800 or whatever, because it is non-linear, but in general it works better than the aforementioned method. It costs about 280$, and an extra MAF, making it more expensive than the previous method.

[Z32TT]

Cant wait to get the Selin, its my next mod.

[BigTDogg (MA)]

Cant wait to get the Selin, its my next mod.

2nd

[TTkickedin]

Bump for 2012. I'm just wondering if this method actually does work?

I've been trying to find other ways to go with a dual intake setup, and if this method is cheaper and works just as good, i'd rather go this route. Has anyone verified this?

Thanks.

[BigTDogg (MA)]

Null and void since the Selin came out, IMHO.

[TTkickedin]

So, you don't know of anyone that attempted this mod?

It doesn't say above that it doesn't work. Then again, not sure how well the vg works on the skyline ECU either. also not sure how this limits further modifications, if at all.

I'm assuming this to be more cost effective than the translator, yet provide similar results..

[BigTDogg (MA)]

Marginally less expensive, and more headaches, IMHO. Especially if the blue connector is different (not sure if it is or not).

I don't know of anyone who's attempted this mod because people usually either:

A) get a SAFC and run two MAFs that way, or ideally
B) get the Selin translator