shakuya88

Prob a stupid question, but how will I learn if I don't ask. What am I suppose to do with this transfer function table? Tuning is a new area for me, but I'm working on it piece by piece

Also, djamps, your tool you have online, it asks for a file to be uploaded. I'm assuming this is meant to be a log file, yes? If so from ROM editor or cipher and a full RPM run?

Massairdirect

I understand your point, but I do not have access to one of those cars. That's why I'm here.

If I could get the voltage points in the ecu I can also make a better excel spreadsheet that has the correct data for the ecu making tuning a lot more simple.

Massairdirect

A transfer function is a 2D table that gives an output vs measurement for a given sensor. For a nissan maf it is voltage output vs. airflow.

An ecu only understands a voltage input from a sensor (or DAC counts) it then goes to a pre-programmed table in the computer code to calculate the units of whatever (airflow/temp..etc.) for a given voltage from the sensor. It then uses math to calculate fuel, timing etc. to run the engine. This sensor lookup table is called a sensor transfer function.

When you change a sensor you need to change this table in the computer code so the computer knows the new data for the different voltages coming from the sensor.

In the case of a MAF equipped engine, it calculates engine load. it takes actual airflow entering the engine from the maf vs. how much air the engine can hold and comes up with a percentage of load. Simply, actual engine airflow vs. theroretical engine max airflow.

load= (maf flow)/(engine displacement)*(air density)*(RPM)

Massairdirect

Does anyone have the stock 64 point maf transfer function?

boostedforlife

iTrader: (3)

I know z1 said the uprev gt handles less whp, but some other tuners I spoke with in Cali say otherwise.....


I have the pmas and don't have any idol problems. Just the hot start where I have to blip the throttle to get it start.

My tuner said if I get the uprev gt I won't have the hot start problem any more,
I'm making about 460 on low boost and going to go e85 plus more, looking to make around 600-700.

Wil I have any issues with the uprev gt?(already purchase it, but can always sell it and stick with pmas.)

djamps

iTrader: (1)

The Uprev GT maxes out somewhere around 500-550whp according to users here. If you plan on making 600-700 stick with the PMAS. The PMAS absolutely does handle more flow than the uprev GT, so whichever tuner told you otherwise should be avoided.

And the hot start issues have nothing to do with the MAF, it's all in the tune... so one more tuner to add to the 'do not use' list.

binder

iTrader: (8)

yep, been hearing a lot of people blame the pmas lately for any issues with tuning. I'm not sure if it's just a crutch to explain their lack of detail in the tune or if they are just trying to milk more money out of the customer by suggesting they need a "better" product.

pmas is fine. tons of people have it with no issues. The tune needs adjusted.

boostedforlife

iTrader: (3)

I don't want to call any names but the tuner that told me was one of the two tunners we have in cali(church automotive and Gtm)

Don't want to make anyone look bad. I thought they both have god names and i doubt they would make things up. But maybe that's the case :/

350z006

iTrader: (79)

Well, it wasn't Church...Church did my previous tunes with the PMAS before the MAF GT came out, and they told me that the PMAS had potentially 800-1000hp capability, at the price of tune resolution and hot start issues.

I have switched over to the MAF GT, only because Church has an easier time tuning them; with the stock MAF pipe the MAF GT maxxed out at about ~550whp, so I had to get a bigger MAF pipe to get it to work past 600whp. If you don't want to change your MAF tubing then stick to the PMAS; it can be tuned, just needs a bit more time and work.

djamps

iTrader: (1)

Tune resolution is indeed different, but hot start issues are very avoidable.

boostedforlife

iTrader: (3)

Pm'ed


So all and all, the PMAS is harder to tune but can handle a lot more power and it really is up to the tuner to fix it from what I compliled here on the forums.

mean while I also ended up emailing up-rev and this was Jared's response.



"Surely a tuning issue. The GT MAF actually adds to the complexity of getting it properly dialed in.

More often than not hot start issues are solved with the "Cranking enrichment mode 1-4" tables. These tables effect the "injector priming pulse" which usually needs to be reduced with larger injectors. The ECU does a "dance" between all the tables, but we don't know when it's in what table so you will have to adjust all the tables at the same time. I usually start by reducing them all by ~15-20% and then making 5% adjustments up or down until it starts to fire up better.

Good luck. "


So according to uprevs response they are saying that the GT is actually harder to tune.....

which one is it? Should I ditch the gt then and try to fix it my self? rather than try to get retuned on it and ditch my pmas?




But this also means that since I have the tuner version I can try to work out my hot start issues my self than trying to get my tuner to do it, as I am in the bay and have to drive back to socal to convince them its them not the maf. Shurgs v

pez1111

iTrader: (2)

Hope the OP doesnt mind me asking a MAF related Q. I have an '06 fitted with an HKS S/C, DW 600's, Cosworth Plenum. I dropped the supplied Fcon in favor of the OEM ECU being tuned by my tuner ( he has written his own software ). He achieved 340HP on the factory MAF. The car has been running really well. Then i got the notion of relocating the MAF from pre blower to just before the TB ( post IC ) I had an 80mm inlet pipe fabbed with a new MAF flange welded in. With the new tune under way my tuner, just before he called it a day couldn't get an idle , said it was all over the place. So until tomorrow i'm reading up and i found this thread. What i have found is the ID on the original OEM pipe and the HKS pipe is 70mm not the 80mm that i had fabbed up, and the IC pipe now steps up from 60mm to 80mm at the TB.
I'm just trying to do some research here so does the change in the ID or a sudden step up of the inlet pipe playing havoc with air flow around the MAF?
Thanks in advance.

350z006

iTrader: (79)

If you're up in the bay area I suggest you go to a closer tuner, like they guys at Z Car Garage...it's just too much hassle to go all the way down here just for a tune, and they may be better at tuning the PMAS as well...

350z006

iTrader: (79)

Sudden drastic changes in piping size can screw up the clean airflow through the MAF, particularly if the change is really close to the MAF sensor...

pez1111

iTrader: (2)

Thanks for that , the step is within about 5-6 inches of the re located MAF.
Here is a pic of the new pipe before i drove it to the tune shop. MAF not yet in.

Massairdirect

You can also send in your HPX or a stock maf and I can recalibrate it. I can put the HPX curve on any stock sensor. It's a lot less money to do it this way then buying another new sensor.

djamps

iTrader: (1)

I always thought this should be possible given my HPX is exactly the same as my OEM maf if you put them both next to each other. based on the failure rate on the GT MAF's I'd venture to guess they are reused OEM's.

Massairdirect

I didn't know people were having problems with the MAF GT. It could be a problem with where they are sourcing their mafs.

Massairdirect

BTW I've noticed a lot of people have tuning problems with the HPX. I also noticed the wrong transfer function was floating around. You will have big problems with tuning and idle if you use the incorrect transfer function.

This is the FORD HPX and the incorrect one http://www.massairdirect.com/resourc...ls/HPXtool.XLS

This is the correct one for the original HPX-N nissan http://www.massairdirect.com/resources/HPXNISSAN.xls

and this is the one for the second generation HPX-N2 stock idle resolution but range of the original HPX-N http://www.massairdirect.com/resources/HPXn2.xls

Hopefully these can get circulated around so you guys aren't chasing idle problems so much and having such a hard time tuning.

350z006

iTrader: (79)

^Thank you sir...good useful info and resources for MAF stuff...