Scaling tune or buy 4Bar MAP

I made a post a few months ago about tuning my 2009 G5 with the 2.2 LAP engine with a supercharger and LSJ injectors. I got good advice but now i'm stuck between Scaling the tune because I am using the stock MAP, or Buying the 4 bar MAP sensor from ZZP and not have to scale the tune.

To scale the tune i read i have to scale by 50% because it is much simpler to do the math. I have 61 lb/hr Deka injectors at 43.5 PSI so i will have to scale if I have the limit to 63.5 lbs. So i multiply the VVE table, MAF table by 50% and then adjust the spark tables as the cylinder mass will change. Is there anything else i have to scale? I know retard tables and other table that have to do with airflow will have to be scaled as well. But what do i do about VVT?

I have not pulled my stock tune out so i do not yet know if i have the 63.5 lbs limit on the flow rate or not. I will post my tune once work on it tomorrow and scale it by 50% to get some advice if i am on the right track. Just buying the 4 bar MAP and tune with it seems to be much more simple, But this is my first forced induction tune so looking or advice.

Thanks.

map sensor....1) you dont have to retune your existing data 2) you can actually read the pressure above where the sensor has run out of data

So i can adjust my tune for the 4 bar MAP and have the ecm read cylinder mass above 1.36 g/s for spark tables? Or are those seperate readings?

I also read the ecm has a limit for airflow, is that true?

kpa/psi is separate from g/s
if you exceed the g/s cap you will have to either re-label the axis for g/s or scale.
try to edit the g/s axis...it should allow certain maximum value to be entered...once that is exceeded then your stuck with scaling.

I just tried to edit the g/s and it wont allow me to do it. So i guess it is time to scale the tune?

I am currently scaling my tune and i noticed some setting based on Barometric pressure. do i have to scale those settings as well? they are under the VVT settings. i scaled the VVT low, med, and high tables already.

any table that has a g/s axis has to be scaled or else the scaling wont work properly

yes i did every table that has g/s in them. Thanks for the help.

I am attaching my tune, if you could have a look and let me know if i missed anything? I think i did everything but since it is my first time scaling a tune i want to make sure i do it right.

Thanks again, you have been a big help!

sorry mate, i just got back to this thread. i work 40 hour weeks and go to school full time for engineering. i just haven't had any time to look into anything in depth. i pop in and out to offer minor advice. thats about all i got time for, sorry mate.

Its alright no worries here. I understand the toll of working full time and going to school, i been through it for the last 3 years. Glad im finished and now have time for my self haha.

I made some changes to the tune i had posted already. I kept researching scaling and kept finding things i had missed. I adjusted some more tables i hadnt changed but i think i am ready already and will be flashing today and see how it goes. Ill be sure to post how it went.

Thanks again for the help its much appreciated!

awesome! good deal man, hope it ends well

Started right up and drives good. The only issue i have is slow response from the throttle, and a little rough idle on start up. Other than that it runs pretty good for the first tune.

Need to adjust fueling, but having trouble setting up the tune file to log vve. Do i copy from LTFT or STFT? I started doing a maf only tune for now to get it running smoother.

you can read both in vve for logs. if your doing short driving then look at the stft as it responds quicker and thus you dont have to wait for the ltft to sort itself out. if you adjust stft enough ltft will fall into place.

I see, so for short drives use STFT. And to fail the MAF i just fail it at the lowest frequency?

Fixed the throttle response by having the ecm go into PE sooner. Was bogging down then taking off, now it takes right off.

An issue i just noticed is when i give it full throttle and the tires spin, the car controls itself by closing the throttle i believe. I already shut off all torque management and traction control. Also got rid of it controlling wheel hop by spark, and still getting cut off. Any thing else i can check? Thanks for the reply btw!

not really that familiar with these newer ecu's. a lot of people claim gains from knock airmass if you have that table available and some of the max boost/pressure tables. you could look into those as well.
its really hard for me to explain stft calibration techniques. at the moment im not coming up with the proper way of describing it and if i rolled with it it would likely provide a false understanding which could cause issues.

I figured out the wheel spin issue. There is an option to enable and disable diff scoring, which is what was shutting my car down when one wheel spins more than the other. Turn it off and it keeps spinning the wheels now. I dont get on it that much so my trans should be fine as i am careful even at the track.

I am trying to get the vve sorted out during the week. Im on maf only tune right now and its running smoother except for start up, where it starts really rich and black smoke comes out the exhaust for a second and then idles fine.

I scaled by 50% and im not even reaching the 1.36 cyl airmass limit. I think i didnt even need to scale 😅

I would recommend calculating the actual Linear and Offset values of your sensor and not just using the product data values. Actual can be a good bit off and changes over time.

Build a PVC pressure chamber with a calibrated pressure gauge, that you can mount the MAP sensor too. Then use a pump or air compressor to charge the chamber while taking readings from the MAP sensor with DMM.

Here is how to calculate the scalar and offset for a MAP sensor.

1. Find the minimum and maximum voltage and absolute pressures.
2. Convert the pressures to mbar.
3. Subtract the minimum and maximum voltages to find the range, then do the same for the pressures.
4. Divide the pressure range by the voltage range to calculate the scalar.
5. Multiply the minimum voltage by the scalar to calculate the offset. Note that a positive voltage gives a negative offset.

Example for a 3.5 bar MAP sensor:

1. For a 3.5 bar data sheet:
0.5V @ 0 kPa (absolute)
4.5V @ 345 kPa (absolute)

2. 345 kPa = 3450 mbar.

3. Voltage range = 4.0V, pressure range = 3450 mbar.

4. 3450 / 4.0 = 862.5 = scalar

5. 862.5 x 0.5 x -1 = -431.25 = offset

So scalar = 862, offset = -431

Plug in the minimum and maximum voltages to check your work:
0.5V x 862.5 - 431.25 = 0 mbar @ 0.5v
4.5V x 862.5 - 431.25 = 3450 mbar @ 0.5v

If you have trouble then draw a graph and extrapolate the lines until they cross the pressure axis.

I can make a How to if there is enough interest.

--Christian

CDNITE, A how to would be great. This is what to do when i get the 4 bar map sensor?

On another note, i am inputting the injector data into my file for the 60lb injectrs and i have a question on how to figure out the "offset vs volts vs map" table. The injector data i have says the offset is .67 ms but im having trouble understanding how to get that fixed. Maybe just leave it stock?

he pretty much did that already: http://www.hptuners.com/forum/showth...ase-file/page4

So i installed my 4 bar map and runs fine. But i am tuning the MAF and the car seems to have a small misfire once it enters closed loop. I dont get a CEL but i can feel it. I tried adjusting the MAF and it just keeps doing it. Maybe my injector tables are wrong? I did get them from a tune a friend of mine sent me that had the same injectors but were ev6 and mine are ev1