MicroSquirt.com read only forum (Jan.15,2018)

Hi,

I'm running ITB's on a 2.0L 16v VW engine and I had some questions about acceleration enrichments. I am using Megasuirt 1 on a v2.2 board with extra 029q and edis for spark and I'm using speed density. What are other people on ITB's using for AE? I been playing with it a little bit, trying each one out but I'm not sure which one would be best. Also would it help to give my map signal more resolution(not sure if that is the right word to describe it) if I were to have a large vacuum canister between the four ports on the throttle bodies and the line to the megasquirt? As of right now I just have the 4 ports coming together with small tees and then going to the megasquirt. Right now my MAP reading is about 50-55kpa at an idle and at a crusise it is about 80-85 kpa. The reason I am asking this is that in the AE wizard window in Megatune I don't get that much action from the mapdot bar on the side unless I really pound it. So I'm thinking that MAP based AE isn't really for me. Any thought's?

Thanks's in advance,
-Dan

Here is your problem. You have two choices of AE activation. Mapdot that is normally fairly good for predicting a need for AE but you don't have much map to work with. Or Tpsdot that is not much use on a ITB setup as there is very little need for AE as the throttles go from 50% to 100% or in the higher RPM range. You will just have to play with the combinations to see what works. The new 2.66 or later code has the x-tau stuff that may be just what you need.

AW

he's running msns-extra.

And there IS a pretty big change in need for fuel between 50 and 100% throttle, at least on my ITB setup.

The only reason to use a vacuum canister really is if your MAP is bouncing.

My car idles at 35kPa, and cruises between 75 and 90 kPa. That's all below 20-25% throttle position. I've written some code that will allow me to use 2 separate tables, one that's Speed Density below a certain throttle position or kPa, and then switches to alpha-n above that throttle position or kPa. (the code can also be used for any combination of speed density, alpha-n or MAF). The idea behind this was that below about 94 kPa, or about 25% throttle, I have good enough resolution with MAP to actually tune with speed density, but above that, the resolution goes to crap, so I need alpha-n to cover the change in fuel requirement from 25% to 100% throttle opening.

Code like this should give you decent steady-state tunability.

As far as accel enrichments go, so far I've had the best responsiveness with TPS based and cycles instead of a set amount of time. For me RPM based didn't work because I could only tune it for one speed of throttle stab and have it work right, MAPdot works alright, but because of the vacuum canister I'm using to get rid of MAP jitter, it lags a bit, so quick jabs at the throttle cause large lean spots (think rev-matching for downshifting), and poor response.

Nothing I've done so far has given me perfect results. Once I get around to testing my dual table hybrid alpha-n/speed density code, and get something tuned, I'll move on to accel enrichments and see if I can't do something there to get good responsiveness AND good control of the AFR. I doubt it'll be perfect but I'm sure I can get something better than the current schemes.

Andy might be right about x-tau though. It may be one of the only ways you can get "perfect" AE behavior with your ITBs, and since you're running EDIS, you could easily switch to ms2.