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Re: [Tigers] Fuel Injection

To: rfraser@bluefrog.com
Subject: Re: [Tigers] Fuel Injection
From: Theo Smit <tsmit@shaw.ca>
Date: Mon, 15 Feb 2010 10:17:24 -0700
Ron, and Cullen,
The Powerjection, like my BossEFI, has a learning mode. It uses a heated 
oxygen sensor and PLX O2 sensor module and feeds its output back to the 
controller.

A downside of the BossEFI system is that while the fuel map is finely 
quantized over RPM and manifold pressure (it has bins for every 300 RPM 
and every 2 inches of vacuum), the feedback mapping is coarsely 
quantized (there is one bin for idle, RPM ranges are 
0-1900,1900-3000,3000-4500 and 4500-redline, and there are only 5 
manifold pressure bins). The problem with that is, if you have a couple 
of points in the base map that are wrong, the feedback compensation will 
fix it but then it changes the compensation factor for a broad range of 
engine operation, and it causes a big shift in the mixture when you 
enter an adjacent bin. The system also appears to not do much 
interpolation between adjacent points (other than for RPM) so with a 
mixture gauge connected to the PLX you can clearly see it change from 
one bin to the next if you have a big step in the base map.

So you need to start with a fuel map that at least generally reflects 
the overall demand curve from your engine, and THEN the self-learning 
will allow it to tune itself as you drive.

The BossEFI does come with a datalogging feature that I haven't yet 
fully explored, but I think that it will be a fairly important tool. It 
shows the input parameters (RPM, temp, throttle, vacuum) and the output 
pulse width as well as the O2 sensor reading. The plan would be to turn 
off the feedback, do some RPM sweeps at various intake manifold pressure 
levels, and see where the holes are.

Cheers,
Theo

Ron Fraser wrote:
>       You need to look for the learn as you go systems.  The earlier
> systems needed a PC to tune the system.
> The newer EFI is using the learn as you go system.   There should be a user
> interface with the unit that lets you scroll through initial parameters and
> then the system tunes itself as you drive.
>
> I'm simply relaying information I have seen in Hot Rod Magazine.  I have no
> experience with any of these systems.
>
> Clearance to the firewall seems to be the only real issue.
>
> Ron Fraser
>
> -----Original Message-----
> From: tigers-bounces@autox.team.net [mailto:tigers-bounces@autox.team.net]
> On Behalf Of Cullen McCann
> Sent: Monday, February 15, 2010 10:16 AM
> To: Wally Menke; Tiger's List
> Subject: Re: [Tigers] Fuel Injection
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