How To: Add Pressure Input for PC-V

[barbagris]

I'll report later on how the first test goes today, but, I may end up just using this as a tool to refine the TuneECU pressure (L) tables and going back to AlphaN mode in PC-V, depends which gets me the best results.

Depends maybe on what you are aiming for. But if I can eliminate the slight "snatch" sometimes at very low TPS/RPM etc then I will be all for it.

 

[Claviger]

First rides done, gave it 20% authority +\- and left the TPS fuel table at where the it was. Set AT to work from 1750-8000 and left the left most 2 columns in the pressure target table at zero.

Within 20 miles it’s already considerably smoother than it was just trying to tune with TPS table only.

Snatch on throttle pickup from closed throttle is almost completely gone already!!

Definitely worth doing @barbagris !!

Since the pressure columns I made match the L-table in TuneECU transferring the values over to the base tune will be very simple so you can dial the base tune as close to perfect as possible l and then use the AT as just an O2 sensor or give it very low authority like 5% for seasonal changes etc.

 

[Kenneth67]

Wonderful work

Question: if this is a much better way to operate, how come bike manufacturers, Dynojet etc don't use MAP vs RPM instead of %TP vs RPM?

thanks
Ken

 

[Claviger]

Alpha N tuning, TPS/RPM is the most crude method and makes the most assumptions, however, it works reliably with engines that use individual throttle bodies well and with engines that change RPM the extremely quickly, like motorcycles.

Most companies now are using a mix of Speed Density MAP/RPM and Alpha N, which is how the Rocket ECU works. This is why we have F and L tables, the F/L switch is the point at which it transfers from running speed density into running alpha N.

Speed density is better at fueling when there’s a strong and smooth MAP signal, something most ITB motorcycles struggle with, however the Rocket seems to be an exception to the rule for whatever reason.

Almost all cars made these days use a different hybrid method of Speed density combined with MAF fueling, I’m not aware of any bikes that use MAF based tuning.

There was a trend in the late 90s and early 2000s to get away from Speed Density and use one of the other strategies, though, that seems to be now flipping the other direction, and increasingly more companies are offering SD tunes for a variety of cars these days.

 

[barbagris]

Definitely worth doing @barbagris !!.

Then so it shall be. Was looking at the maps etc this afternoon. I force the use of MAP/RPM more than OEM - so doing this with the PCV makes sense.
What I am trying to decide is where to cut the F/L values now. I think I'll leave it as is for now and just flip the PCV mode.
I also have my @Speedy inspired MAP variable volume damping plenum sat untried. Though it sounds as if it is not necessary.
No ruddy positaps - I am going to have to remove something like the Fuelbot harness!

 

[Claviger]

The MAP buffer you have will help. I’m getting a little bit of surging at one point where it swing lean/rich/lean back and forth as a result of vacuum going back and forth.

It may not happen to you at all, it’s caused by reversion... big cam issue.

 

[barbagris]

The MAP buffer you have will help. I’m getting a little bit of surging at one point where it swing lean/rich/lean back and forth as a result of vacuum going back and forth. It may not happen to you at all, it’s caused by reversion... big cam issue.

I'll start without then. And take it from there. If you need a MAP buffer it wont be a hurdle to make another.

 

[Claviger]

I’m so close to perfect I’m just going to transfer today’s values over to the base and cut authority to 5%, this seriously fixed 99% of the tune errors I had. Runs beautifully now.

 

[sleeves]

Nice post and explanation thanks am going to experiment with this, was reluctant to try and tap the stock MAP sensor into the PCV but looks like its OK.

Good job there.

 

[barbagris]

I’m so close to perfect I’m just going to transfer today’s values over to the base and cut authority to 5%, this seriously fixed 99% of the tune errors I had. Runs beautifully now.

Dynos - we don't need Dynos. We got a @Claviger - more useful, definitely cheaper.

What's more is he is obviously used to making complex stuff comprehensible (if not actually understandable) to those with occasionally lapsed mental acuity. This is a rare skill in any technophile.