aloha,

i have set up a web page with graphs generated by crome software that illustrate
differences between fuel and ignition control data for the above mentioned ecus.

there are 4 graphs: each graph overlays the p28 d16z6 vtec obd1 data in a lighter color over that of the p08 d15b vtec obd1 data for comparison purposes.

the horizonal axis is rpm and the vertical axis for fuel is milliseconds ( theoretically) that the injector is open while the verical axis for ignition is spark advance in degrees.

each curve represents data for a given manifold pressure ranging from closed to wide open throttle.

so, for example, the top curve of each graph is manifold pressure/vaccum at wide open throttle while
that of the lowest curve is for closed throttle.

i started this thread to encourage others to post graphs of similar data for their custom setups or comparisons of stock setups or whatever floats the old boat.

Njoy:

http://home.insightbb.com/~johnny8ch/p28vp08.html

 

Nice, would be cool to see an overlay of P28 vs P2P ECU as a lot of people use the P28 for D16Y8 swaps without the P2P basemap.

 

i will try to do that this weekend --

 

Sweet, could you possibly give an overview of what the graphs are showing? I kinda dumb to the whole timing/fuel curve chart. Like why the multiple lines?

 

Replying to sub.

And would have happen to have the crome map for the p08 I may be getting a obd2 d15b vtec at the end of next month.

And would also love to see the p2p since everyone thinks a p28 stock will run a y8 just fine.

 

In order to read graphs:

So, crome spits out 4 graphs for vtec ecu-s. Those are:
Fuel- Low Cam
Fuel- High Cam
Ignition- Low Cam
Ignition- High Cam.

The Low Cam is the NOT VTEC cam and the High Cam is the VTEC cam.
Low=Vtec Off
High=Vtec On.

The Fuel Curves can be read as follows:

1) Look at left side vertical axis label and note that it says Duration(ms).
This is the duration in milliseconds that each injector stays open.
2) Look at the bottom horizontal axis label and note that it is RPM.
3) Observe that there are a bunch of curves or solid lines that connect points:
a)The points represent the input/output data for the ecu. The inputs are manifold
pressure and rpm, and the output is the duration that the injector is open.
b)The curves are created by connecting the points at a given manifold pressure across the rpm spectrum. For example, take the topmost curve. That curve is for Wide Open Throttle(WOT) or low manifold vacuum/high manifold absolute pressure. For each rpm at WOT the computer will "look up" in its "map" the approriate or designed amount of time to pulse the injector. So, follow along the curve and note from low to high rpm that the injector stays open longer giving you more gas in the cylinder. The lowest curve represents closed throttle or high vaccum/low absolute pressure, and those in between are for manifold pressures between closed and wide open throttle.

4) Topmost image shows the manifold pressure points used in maps and confirms that same pressure points are used in each map so that overlay is meaningful. E.g. 4th curve up for p28 manifold pressure ( 519 mbar) is same as 4th curve up for p08 pressure.

For Ignition:

The idea is the same except the left vertical axis is spark advance in degrees.

The interesting deal is that i have OVERLAID the p28 curves onto those of the p08 and you can get a visual feel for the differences.

The p28 curves are lighter in color than their corresponding p08 ones. So, to appreciate this, take the highest, lightest color curve and that represents WOT for the p28 then take the highest darker color curve and that represents WOT for the p08.
You can do this for low and high cam. Note on low cam how the lighter colored p28 curves are generally higher at low-mid rpm than those of the p08 leading to a slightly rich mixture.

Of course, the condition of an mods done to your motor will change all this, but its interesting to see the differences for the stock setups.

Hope this helps.

I am looking at replacing d16z6 with d15b and wanted to know the difference between the ecus.

NOTE:
i dont really know why points exists for vtec on at low rpm and vtec off at high rpm --
anyone know ?

 

Thanks that help clear it up a bit for me. You may or may not have access to this but another great layover would be the P2P vs P2J (SOHC 3 stage VTEC) as many people just throw the P2P in there when they do the swap. I'm gonna post the pics from your site just in case people don't have outside link from their workplace.



P28 VTEC OBD1 ECU DATA OVERLAID ( lighter color) ONTO P08 VTEC OBD1 DATA
USING:
JDM D15B VTEC OBD1 (P08-001-237.bin) for P08 and
D16Z6 (304stock.bin) for P28
from pgmfi.org with crome1.6.5 ( thanks)
ENJOY

 

ATTENTION ---

I JUST NOTICED THAT I MADE A MISTAKE IN OVERLAYS --

i assumed that the extents of the duration graphs were the same for all graphs and that was wrong --

so, i am will fix ,

but, disregard these overlays for now they are off --

i was working on P28 over P2P and realized that i had f**d in an upwards direction -- its always better to do that in a downwards direction i guess ?

sorry for confusion

 

ATTENTION AGAIN --

I FIXED THE GRAPHS ---

So, please remove inline images that represent erroneous graphs, thanks for your patience.

I Plotted Fuel Value vs RPM --

does anyone know what the fuel value translates to in the real world -- i mean, i understand that it relates to injector duration, BUT .. say you use a p28 ecu with stock maps for d16z6 and control a d15b with it. Do the "Fuel Values" from crome directly correlate to the fuel injector pulse duration?

If so, without any tuning, it appears that the p28 will be giving a rich mix for the d15b over almost all rpms and manifold pressures. Of course, in closed loop, O2 sensor will lean the mixture i guess, but wouldnt it be better to have a target closer to what you want ?

I dont think that i will run a d15b off of this p28 without p08 maps on p28.

Any inputs will be appreciated, thanks.

 

ADDED another set of graphs for p28 vs p2p

spark timing looks whacked but it matches data.

check it out:

http://home.insightbb.com/~johnny8ch/p28vp2p.html

 

this is excellent information to have. Sticky?

 

i dont know what "sticky" means or how to implement it