127.5 in 0 TPS Column

[VDeuce]

Something that's bugged me for a while in my PV map...

- 2007 Street Glide, 120R, 662-2 cams, HPI 55mm, Boarzilla -

I have a TPS based PV cal and am getting maxed out VE values in my 0 TPS column from 1500-3500 RPM. Using auto tune pro with widebands. AutoTune wants to max out the values in this decel column. Absolutely no exhaust or intake leaks (verified).

Is this something that is addressed in the MAP bias? Ideas?

[rigidthumper]

It's just trying to flood out the decel pop. Not a huge deal.

[Jamie Long]

Cannot use O2 sensors to tune the decel area

[Gordon61]

Hi Jamie, I've seen you say this before and about setting the minimum MAP value higher when autotuning so as to avoid collecting that data

I found I got a smoother tune if I DID collect the Decel data, and I've negligible pop fart or otherwise

I've seen someone else's VE tables that were done by TT and they seemed waaay too high compared to mine even though the builds should have been reasonably similar ...is this a PV and Wideband vs Narrowband phenomenon? ...I only have the stock narrow

Rigidthumper, I presume it is trying to richen a lean reading from the O2's given the PV doesn't actually sense pops n farts, surely

[harleytuner]

That's one of the problem with auto tune systems,.  When you let off the throttle the bike goes lean and AT want to add fuel.  It's doing this in the other areas as well just not as bad as the zero column. 

[Gordon61]

I suppose that raises the obvious question ...so how do you properly tune the VE tables in the decel area, even with a dyno??

Is this anything to do do with the response time of narrowband being much better than wideband that I seem to get ok numbers with the built in autotune routine, but widebands maybe don't?

VE(TPS) tables must also present a complication in that many of the cells are trying to cover a range of KPA, so the VE is only an average, of presumably quite a range? no?

[rbabos]

That's one of the problem with auto tune systems,.  When you let off the throttle the bike goes lean and AT want to add fuel.  It's doing this in the other areas as well just not as bad as the zero column.

Yup. This very quirk makes road tuning a vrod a complete pain in the ass. Been there, done that.  Knowing what values are more in the norm rather then accepting the AT crap can make a huge difference. It will always overshoot a decent afr to one that's too fat and the resulting engine running suffers. Dyno tuning, the load / fueling should have more control. In theory. I can only comment how much AT devices suck in light load areas when road tuning. That, I have plenty of experience at. My big twins suffered the same fates but those engines are more tolerant of less then stellar afr mapping.
Ron

[Jamie Long]

The decel area is volatile, there is much more in this equation. There are transients, decel fuel cut, reversion, & other characteristics of the decel region that are very different than when under load, you need to give the motor what it wants whether this is more fuel, less fuel, or cutting the fuel off completely.

[VDeuce]

I should just go back to a damn carb 

[rbabos]

The decel area is volatile, there is much more in this equation. There are transients, decel fuel cut, reversion, & other characteristics of the decel region that are very different than when under load, you need to give the motor what it wants whether this is more fuel, less fuel, or cutting the fuel off completely.

There in lies the problem with auto tuners in general. Knowing what the engine wants comes with a "Potty mouth" load of trial and error road tuning, or several means of sampling on a dyno again with an experience operator that knows what is going on from years of experience. Seldom, it will be what the auto tuner gives you in the low end and light load areas and will bite a first time user in the ass 9/10 times.  My case, data was not even close evident by engine behaviour  so even a cabbage head like me will eventually will make use of the software to produce the effect needed to cure a certain conditions. Did I mention road tuning a Revolution engine sucks and is quite challenging. It can be done but takes a while.
Ron

[rbabos]

I should just go back to a damn carb 

Where's the fun, aggravation in that?
Ron

[Gordon61]

None of this actually answers the question "...so how do you properly tune the VE tables in the decel area, even with a dyno"

If the O2 sensors report x ...you can do whatever you want but CLI and AFF are going to bring whatever you do right back to x ...and probably mess up other parts of the tune because the AFF block tables are not detailed enough to segregate different areas.

Ah ok, unless you switch off closed-loop ...now, just how many combustion engines don't use closed-loop again...?

[VDeuce]

I should just go back to a damn carb 

Where's the fun, aggravation in that?
Ron

I ran a Mikuni HSR48 with DTT ignition on this bike for a short time. It ran extremely well but there were some annoyances that turned me back to fool injection. It was hard to start, ran out of fuel at WOT due to the small bowl and also produced fuel standoff that you could smell under certain conditions.

But man, that thing made for NO low speed issues at all - smoother than any EFI combination I've tried. It gave the engine exactly what it wanted.

There is something to be said for the analog world, lol!

[joe_lyons]

Look at the trends that are happening in the 2, 5 and 7% tables and work down towards the left.  The is a feature called decell fuel cutoff that shuts the injectors off at a certain KPA and TP.  With the injectors shut off the afr shows lean and the widebands record this and tries to alter it.  What are your KPA values on decell?  Please post your map also.

[Gordon61]

What are your KPA values on decell?

Hi Joe, I've heard mention of this once before ...what were you thinking they should look like if you have a minute to explain?

ta