N62/Z32 MAF Sensor

[modulation]

I was wondering what those who have N62 mafs changed your raw injection multiplier from/to in order to get it to work.

I have a NA ka24de and I am trying to put a N62 MAF on it.
I know I have the wiring right but something isn't working correctly with the ECU/Software as it idles really rich and dies if I don't give it gas..

I know I'm changing it (mafs map) successfully in the ECU because when I change it to the z32 one and use the KADE MAF it won't idle correctly unless I use nistune to change the AFM back to the KADE one.

The mafs might be bad, but I put the mafs on a bench, gave it 12 volts, and the voltage from the output would change from 0-1.5Volts when I put a shopvac on it.

Do I just need to play with the injection multiplier until I get a smooth idle, or will I need to retune the whole A/F table?

[Matt]

I'm not familiar with the N62 MAF... Is this the same as a Z32 MAF?

If not, can you get a ROM image with the VQ map for this?

You will need to adjust the injection multiplier from the looks of things firstly, and make sure you have the correct voltage to load calibration (VQ) map secondly

[datsunboy]

the N62 maf IS the Z32 maf.
RB20 mafs are N60.....e.t.c.

[Matt]

Is that the manufacturer part number?

You should be able to select Z32 from the drop box and run from that. If thats what you did, then your injection multiplier will need adjusting until it is running correct AFRs throughout the rev range

[modulation]

Is that the manufacturer part number?

You should be able to select Z32 from the drop box and run from that. If thats what you did, then your injection multiplier will need adjusting until it is running correct AFRs throughout the rev range

Ok that is what I was wondering.
I know the drop down box selects the VQ map for the MAF but why can't it also modify the injector value the proper amount too?

I would think the value for one Z32 mafs would be the same for another, obviously not so please explain why so I'm not so stupid.

The N62 I think does have to deal with the P/N.
N62 = 300zx
P60 = q45
http://lh3.ggpht.com/jonhamilton/SCOYZ1 ... C02184.JPG

[Matt]

It does adjust the injector multiplier, but with the HP its using, that may be incorrect

There is a horsepower (HP) number associated with each VQ map. Most of the Japanese ones are known, but the American models still need more information to get it right

This is defined in your vqmap.def file located in
C:\Program Files\NIStune\VQ Maps

That file contains estimated HP flow through the meter. eg.
Z32_VG30DETT_VQ_MAP.bin,Z32-VG30DETT,500

I currently have S13 KA24DE
S13_KA24DE_VQ_MAP.bin,S13-KA24DE,190

That looks to be too low, probably around the 280-300 mark. It depends on the max HP that the MAF can read

When the max numbers are spot on, the auto selection will work well. However for now you will need to do the adjustment and let me know what K ends up being

If you can tell me what you end up using as a multiplier to get your mixtures better, I can work out the estimated KA24DE MAF HP against the known Z32 MAF HP and update this file

[modulation]

Matt,

Thanks for the response I understand now. One thing that I never would have imagined about nistune is the excellent customer support.

I will play around with the K constant injection multiplier and let you know what number works the best for me. I have a lc-1 (which works great with Nistune btw) and I'll use it to find the right injection multiplier. From what I understand I need to go lower with the injection multiplier right?

Might be this weekend before I can get around to it but I'll let you know the number once I get it.

[Matt]

Larger injector changes the multiplier goes smaller
Larger Mass Airflow Meter changes the mulitplier goes larger

[modulation]

Larger injector changes the multiplier goes smaller
Larger Mass Airflow Meter changes the mulitplier goes larger

Thanks I guess I had the two confused..

Ok another stupid question.
My KCONST Raw Injection Multiplier seems very high? When I see screen shots in the nistune user guide the kconst there is in the hundreds (I know it's a different engine/maf.) When I look at mine it's 39720. When I switch to the Z32 MAF it only changes to 38990 (it goes down.) This seems opposite of what you said which is why I decided to mention all this.

[Matt]

The K constant (Injection Multiplier) is a magical number used in the whole pulsewidth calculation.... and is very different between different types of ECUs. For example the R31 value is something like 768 decimal

All changes are based on percentage of adjustment, which is why we added the 'percent' field to the constant values so you know how much you have changed them by

Using the auto box comes in handy when the engine is just running and you can use + or - on the key board to increase/decrease until it starts idling better

I checked with S13 CA18

Injection multiplier calc:

Current K 183 * (new 500 hp / current 190hp) = New K 481

So you can see an increase in K here

Your calc would be 39720 * (Z32 500 hp / current 190hp ) = 104526

We've hit a problem here though. The ECU uses a '16 bit number' which is a number between 0 - 65535. The final calculated number falls outside of the range

Looks like the calculation overflow is a result of 104526 - 65536 = 38990 which is what you got.

Thats interesting.... theres an upper limit for this ECU on the K constant. I'm going to have to add a warning box in for this one....

Lets assume that your AFM is capable of measuring 280hp

39720 * (Z32 500hp / current 280hp) = 70928... thats still going over the top. The most you can adjust K to is 65535 with that current K constant

Let me have a look at it later tonight and I'll get back to you on this one

[modulation]

I checked with S13 CA18

Not that it matters that much (or at all since they are both 16 bit) but I have a ka24de. Thanks for checking into this!

It seems to me that a work-around would be to upgrade to larger injectors first and then upgrade the MAF.

[Matt]

Yeah thats fine I knew you had a KA24DE but I didnt have that on hand when double checking what everything did

The second set of calcs above was using your K constant. You are right, if you do the injectors first and then the MAF afterwards then you should be okay