Changed injectors, MAF Translation?

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my1path
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Changed injectors, MAF Translation?

Post by my1path » Sat Jun 08, 2019 12:54 pm


SETUP:

VG33e Running 1990 M30 ECU
Stock injector size 185 CC (stock vg33e)
New injector Size 344 cc, as tested by the cleaning service(stock VG33er).
Been Sitting about 200 hp N/A and I changed because I'm getting ready for a little boost from a supercharger

Chasing 14.7:1 AFR under light load I've now got the K Const at 230 (was 345) and latency is 800 (was 750) to get the idle close.

I understand K Const also effects the TP scales... Now only 2/3 of my existing load scale is being used and I'd prefer to stay close my existing load scales rather than adjust everything down. I do not have the feature pack, which I suppose would have made this easy, so I guess I need to adjust the MAF Translation (VQ?) map. I have not touched this map before and I want to make sure I'm taking the right approach.

I see a peak of 4.2v in Trace on a WOT run. So I guess I should start moving the top of the MAF Translation curve (5120mV) so that it peaks closer to 4.2 (4240mV) until I can reach my desired TP cells on the TP scale?

I'm sure if I move it all at once the bottom of my curve will start messing with idle/ low RPM and there's
like 50 cells in between to keep smooth... Its not linear and I do not see a % change option.

Is there any specific strategy to this?


To muck things up even more (lol), I have another MAF on the way that I'm curious in trying. I think it will fit my plumbing better than the M30 MAF I've been running. This other MAF is plentiful and cheap here. It also removes from the housing allowing easy use of custom housings, if needed.
I don't know if its listed in Nistune, comes from lots of 98-04 3.3L Nissans/Infiniti including the supercharged models.
Nissan PN 22680-7B001, HITACHI PN MAF0025 (OEM)

Before I get flamed with ways to throw money at my plumbing situation: Stock Air box is a must and Stock looking MAF to intake boot is desired.
I have part of an M30 boot glued to shortened stock boot, It looks stock but after ~6 years that solution is beginning to fail me. I have a new stock boot and I'd like to use it unmodified this time, In that way it should last "forever".

my1path
Posts: 41
Joined: Fri Apr 06, 2012 8:06 am
Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Wed Jun 12, 2019 6:25 am

No advice? I'm guessing not a lot of people have had to mess with this map. I tried moving the MAF Translation numbers a little bit but I didn't get good results. This will take some time so maybe I should hold off until I get my final plumbing configured....
For the time being, timing seems to be close enough, I made some fuel scale and fuel map changes. I runs good which gives me time to get other things sorted before try again with the MAF Translation... Hopefully someone will chime in with a good strategy by then.

Pic is the vg33er supercharged MAF I'm contemplating.
It's more compact than the n60 so I hope I can make it work for my plumbing.
VG33ER Stock MAF.jpg
vg33er stock maf
VG33ER Stock MAF.jpg (83.78 KiB) Viewed 231 times
Attachments
KIMG1426~2.JPG
vg33er supercharged MAF
KIMG1426~2.JPG (847.96 KiB) Viewed 231 times

my1path
Posts: 41
Joined: Fri Apr 06, 2012 8:06 am
Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Wed Jun 12, 2019 10:29 am

Google is telling me that "afh70-16" is also found on the SR20ve MAF.
I'm hoping this means I may already have a working MAF table for this MAF...

Matt
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Re: Changed injectors, MAF Translation?

Post by Matt » Thu Jun 13, 2019 5:28 pm

Landed in hospital, hence the delay in my reply
Now only 2/3 of my existing load scale is being used and I'd prefer to stay close my existing load scales
You may have toe adjust the load scales if you are only using 2/3 of them to get full use of them

Adjusting the load scales themselves is not the kicker, it is where load runs through in the closed loop and knock regions which usually don't have adjustments available, so I added TIM to a limited number of ECUs
I need to adjust the MAF Translation (VQ?) map
Adjusting VQ is similar to adjusting K, they both change the final TP load result. So if you increase whole VQ by 10% or K by 10% it does a similar thing since
TP = MAF (VQ) * K / RPM

I've not used that MAF. You would need to extact the VQ curve from an ECU which ran that MAF. That way you can then use the VQ curve directly with Nistune. Given its around 98-04 you may need to use K-Line with the ROM raider tools to connect to the same vehicle to dump the ROM and then get the file. I don't have those ECUs here (or the matching file)

my1path
Posts: 41
Joined: Fri Apr 06, 2012 8:06 am
Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Sat Jun 15, 2019 7:22 am

Matt wrote:
Thu Jun 13, 2019 5:28 pm
Landed in hospital, hence the delay in my reply
OOF! I hope to your fast recovery, are you ok? I realize you have probably have a full plate even on your best days.

Thinking it out typing it in the forum helps me process some ideas and formulate new ones (see below) even if replies don't come. After toying with it the some more I realized TP scales were not as off as I thought and it was easier to leave the MAF Translation alone. The Fuel scale was larger than the timing scale so fueling was more effected. The timing scale I left alone, a trace shows everything sits really close to the way it used to be. I ended up copying the timing scale to the fuel scale so they are now the same and it was really just that simple, AFR's are just where I want them to be thru the range. (I got lucky?)

I've decided to re-tube my N60 MAF and make adjustments to that since the curve is known. I know, most folks re-tube larger but I'm re-tubing smaller to fit stock plumbing. This should have the opposite effect on my K value compared to my injectors. If I end up topping out with the N60 Re-tube then I can do the same with an N62, again working with known curves.

Speculation: I don't think I would top out a re-tube MAF... Not right away.
If the n60 is good to 300 HP and my re-tube is 10% smaller I'll theoretically be capped at 270 HP.
I'm pushing about 200 HP N/A after I add 4 PSI boost I'll probably be in the 250 ballpark...
Close, if I swap blower pulley's I would certainly need more headroom.

Matt
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Re: Changed injectors, MAF Translation?

Post by Matt » Sat Jun 15, 2019 9:09 am

Thanks. Going to be a long one... foot got pretty messed up and needs multiple ops

With the MAFs, once you change the tube size, it will need recalibration.

To get an idea of what it looks like, play with the MAF scaler tool using the HPX/R35 sensors. With the HPX I have the polynomials to generate any curve, but the other models just get lifted from the donor ECU (which Nissan put the curve in)

The only way I can see that you can recalibrate on the dyno is to have your current fuel map exactly what you need, and then adjust the VQ curve to the new map to get it back to the same

my1path
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Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Sat Jun 15, 2019 4:57 pm

I was certain It would need adjustment after re-tubing but will the curve change dramatically or just need shifting?
I'm hoping the Curve will be similar and just need shifted a little.

Dimensionally the other MAF was not what I thought it was and I do not have the capability to extract the correct curve from its parent ECU. Two good reasons to send it back.

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Re: Changed injectors, MAF Translation?

Post by Matt » Mon Jun 17, 2019 8:43 pm

Looking at changing the MAF tube size with the HPX, the whole curve gets shorter/longer

my1path
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Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Tue Jun 18, 2019 10:25 am

Interesting, sounds like this could get challenging. So I'm thinking of running a trace against a flat fuel map with my old MAF and then again with the re-tube and make changes until they match? Does that work? I figure that would rule out cell averaging as a variable.

I did some digging and found out the RB26 (J70) MAF is the correct smaller diameter but price and availability make it less desirable to me.
BUT is it possible the J70 MAF has the same internals as an N62 just a smaller housing?

Matt
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Re: Changed injectors, MAF Translation?

Post by Matt » Wed Jun 19, 2019 12:33 pm

I'm not sure last question. Yes if you ran races and compared old/new MAF with adjustments until resulting AFRs were the same in the trace then you should be fine (injection time should also probably trace the same between old/new)

my1path
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Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Thu Jun 20, 2019 12:14 am

Odd, I'm not getting email notice. I've checked and double checked that I'm subscribed. There's nothing in my spam folder but I have to come back manually to see replies...

my1path
Posts: 41
Joined: Fri Apr 06, 2012 8:06 am
Location: Southern CA, USA

Re: Changed injectors, MAF Translation?

Post by my1path » Mon Jun 24, 2019 2:54 pm

UPDATE:
Got a spare z32 MAF to play with, I got a deal because the housing was drilled and screens were missing... won't matter anyway. I hooked it up and tested it today. "Chang MAF" worked pretty good and the unit peaked at 3.38v on a trace. Instead of a complete re-tube I'm going to cut the last inch (25mm) off the MAF and bond a reducer inside it. The tube diameter will remain unchanged for at about 1.5" (38mm) before and after the MAF element.

Pic Not 100% accurate, but quick visuals help.
MAF housing.jpg
MAF housing.jpg (30.02 KiB) Viewed 118 times
Blue= Z32 MAF housing (2.8 ID)
Purple= Removed portion of housing (2.8 ID)
Red= Reducer (2.8 ID to 2.5 OD)
Orange= MAF sensor element

my1path
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Joined: Fri Apr 06, 2012 8:06 am
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Re: Changed injectors, MAF Translation?

Post by my1path » Sun Jun 30, 2019 12:53 pm

New housing is the same ID as the factory housing (2.83")
Trying to reduce the stock housing and have it end up the length I need was getting too troublesome so I just cut the mounting flange and electronics box off of and put them on my own custom reducer tube...
Add some black paint and some road dirt and hopefully it shouldn't look too obvious
Z32 Custom MAF housing_sm.jpg
Z32 Custom MAF housing_sm.jpg (163.77 KiB) Viewed 89 times
I'm not sure how far before and after the sensor the diameter matters so I gave it 1.5" in either direction from the center of the sensing element and this is why it sticks out behind the flange. I also left the reduced end long because it extends past the bellows and keeps the air smooth on its way to the throttle body.
Test drive went great, maybe I didn't notice it the first time but my AFR's are fluctuating less than they used to on the right side of the fuel map. I assume this is because the N60 and N62 have different sweet spots for accuracy.

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