PC III AccelPump

[lemppari]

Says Manual: 'The number of engine revolutions during which fuel is added.' According to the Manual, some use 15, others 20 and I can decide which.....In plain English please, what do they mean by number of revolutions etc.

 

That cannot be a specific RPM, neither a range where within the accel pump feature would function. Once again I feel I'm dumm or downright stupid, but I just can't get it. Somebody please explain, I'm beggin'ya!

[gstallons]

You can trim the fuel injector pulse function to 15 or 20 crankshaft revolutions.

Well....... number of revolutions means= the number of revolutions.

What do you not understand? I think it pulses the injectors for a specific # of crankshaft revolutions before it ceases to pulse in case the engine does not start. This will stop the engine from flooding if it does NOT start.

BTW, 15 crankshaft revolutions is a LONG time..............

[lemppari]

You can trim the fuel injector pulse function to 15 or 20 crankshaft revolutions.

Well....... number of revolutions means= the number of revolutions.

What do you not understand? I think it pulses the injectors for a specific # of crankshaft revolutions before it ceases to pulse in case the engine does not start. This will stop the engine from flooding if it does NOT start.

BTW, 15 crankshaft revolutions is a LONG time..............

Yep, that was explaining it in plain English. I should try to find a 'Fuel Injection Control for Dummies' book, perhaps! Well, the rest is good old trial and error testing.

[gstallons]

No problem, ask questions, we will help........ I will help as much as possible.I am not sure if these injectors are sequential, if they are triggered with every ignition pulse or every crankshaft revolution. EMRY (a member here) is also a good help on these matters

[luhbo]

Does "acceleration" in plain english mean "starting"? Is it a problem of language at all? If acceleration translates to what I think it should to, then 15 turns normally turn out as a rather short time. 20 is not much longer btw.

Of what amount of additional fuel are you talking? Can you adjust this value as well?

 

hubert

[gstallons]

As I understand the term as written: it would mean the same as pumping the accelerator on a carb. engine with a acc. pump. to put more gas than normal in the intake to help with starting.

[felix42o]

On a carburator, the accelerator pump functions (as I understand it) to squirt a little extra juice on initial throttle openings to compensate for the lag in engine vaccuum right after the throttle plates open...maybe this is the same idea? It's supposed to help keep the engine from leaning out while Bernoulli gets his crap together in that first few seconds after you stab the throttle.

[luhbo]

No, it has nothing to do with starting the engine, although you can use this pump in case you don't have a choke (older Porsche engines e.g.) nor a starting (secondary) fuel circuit/carburetor (as featured by Dell'Ortos).

Bernoulli on the other hand is "thunder-fast", what for the small distances in a carburetor or inlet duct is quite the same as the usual lightning-fast (in relation to the speed of the rest of the parts, valves, pistons,..).

So basically at the same moment as you open the throttle the pressure inside the inlet duct rises, also at the same moment the vaporised fuel condenses and either falls out at the duct walls or floats around as rel. heavy dropplets, staying way behind the still lightweight and because of the now higher pressure quickly accelerating airflow down the combustion chamber.

 

Anyway, the WM15 has a well working pump emulation implemented, so why don't you just set the PC thingy right to zero?

 

hubert

[lemppari]

After two test rides, the thingy got disconnected altogether and I'm continuing with the Tuneboy theme. As I've written in another thread, I had some mysterious cut-outs previously. Then I took the PC III off and rerouted it's cables and sat it on the tooltray trying to eliminate any pressure on cables and connectors.

 

I was riding to work on a curvy B-road today that's nice and bendy, and in one particular righthander I leant out going about 110 kmh, the engine doing 4100-4200. At the apex I slammed the throttle wide open and had a total injection cut-out. NOT a nice thing to happen on a narrow road when you're hangin' out with all you got. After that I began testing and yes, the engine would cut almost every time when opening the throttle fully, between 4250 and 4750. So the PC actually works as a decelerator pump and I believe that's what brakes are for!

 

In the afternoon I took the same road back with the PC disconnected and had heaps of fun, no cut-outs but the initial hesitation at little over 3000 which was the reason for purchase of the Thingy in the first place. I can live with that. Litterally.

[luhbo]

Sometimes it's hard to tell an engine dying of starvation from one simply drowning. Most people are drowning their engines (it's easy with carbs).

What you describe could be drowning as well. With the standard ecu. They're usually well on the 'safe' side. If the PC pump makes things even worse then this may be another hint in this direction.

 

Hubert

[lemppari]

Sometimes it's hard to tell an engine dying of starvation from one simply drowning. Most people are drowning their engines (it's easy with carbs).

What you describe could be drowning as well. With the standard ecu. They're usually well on the 'safe' side. If the PC pump makes things even worse then this may be another hint in this direction.

 

Hubert

 

That was just what I suspected. The thingy probably drenches the spark as I have set the TPS a bit high to 532 mV at idle and looking at the chart values, the PC gave substancially bigger squirts at between 4-4500 rpm. I have been trying various maps from the PC site and from this forum, but the wisest thing is to insert a zero map and do a dyno ride, after which one knows exactly what needs to be altered, if anything.

 

As things are now, I get a crispy throttle response and enough power from the stock ECU too, only experiencing the slight drop at around 3-3200. Then again, that's what the gearbox is for....