Questions on TFI

[glider]

The TFI comes with pre set instruction settings for your application and from there you can tweak the settings to the leaner side to get the better feel of the throttle crispness.

There isn't a need for a dyno using the TFI and anyone that knows basics about tuning can set the TFI up where the bike runs the best without using sniffers etc to test AFR.

Like I have stated many times, the TFI is all that is needed for a street ridden bike to add some fuel. If you are concerned about AFR the way you seem to be then other more sophisticated tuner choices and a dyno tune would be your best choice.

As far as setting pot#1 at 1800rpm, in this area the pot effects the low speed to mid fuel delivery and at that rpm, it is easily to detect the engine speed changes that the settings are making. It's not rocket science and I think you are reading a bit much into the picture. The intake has sensors like mentioned above that will adjust for varying loads and throttle positions and compensate with different pulse widths to the injectors (time opening). These pulses are sent out by the ECM and the TFI will modify them to the pre set values that the unit has been set to by the user.

 

[harley@16]

I think it is in closed loop because the resister alows a normal reading to be picked up by the ECM. The only thing is its' value never changes

 

[recharge]

Here's a couple questions. First where do most people put the TFI, under the seat or should you be able to see it when riding, and how is the best way to tell your rpm without a tach or just the best guess.

 

[glider]

The 1800 rpm's isn't that critical, just use a higher than normal engine speed to set the #1 pot.

The TFI can go anywhere as long as it fits, it doesn't have to be in sight but what I do is ti use a piece of stick on velcro and attach it to either the tank or air cleaner until you get the adjustments done then move it to the area where it fits and bundle the excess wiring up with a tie wrap.

 

[harley@16]

1) What exactly does the O2 bypass do?

2) How is the idle mixture adjusted independently from cruising RPM's?

3) They make claims of the fuel metering being accomplished by load rather than RPM's. Can someone explain exactly how the load is determined or sensed.

I'm sure I'll have more questions so bear with me.

Thanks...Jim

I was curious so I e-mailed the manufacturer and the answer is: the resistor in the o2 bypass gives a reading of 3 volts which the ECU considers unreliable information so the
ECU runs in open loop at about 14.5:1.

 

[Bud White]

I was curious so I e-mailed the manufacturer and the answer is: the resistor in the o2 bypass gives a reading of 3 volts which the ECU considers unreliable information so the
ECU runs in open loop at about 14.5:1.

14.5 to one isnt much open loop its barely richer at all .. but i guess since its adjustable with tfi they are just trying to force it to open loop .. which doesnt make much sense why not start about 13.8 and go from there


I put mine right next to my fuse box

 

[glider]

It's not recommended to try to adjust the TFI as you ride. I think what Steve was saying is that it is accessible doing it this way but pull over and make the changes.

 

[harley@16]

that's what I thought but I just had to ask because I wanted to do it riding but never imagined it would be poss.

 

[slimjim47]

I was curious so I e-mailed the manufacturer and the answer is: the resistor in the o2 bypass gives a reading of 3 volts which the ECU considers unreliable information so the
ECU runs in open loop at about 14.5:1.

Everything I found says the ECM will set up at 12:1 if the sensors are disconnected. Going from 14.7 to 14.5 sounds a little flaky.

The TFI comes with pre set instruction settings for your application and from there you can tweak the settings to the leaner side to get the better feel of the throttle crispness.

There isn't a need for a dyno using the TFI and anyone that knows basics about tuning can set the TFI up where the bike runs the best without using sniffers etc to test AFR.

Like I have stated many times, the TFI is all that is needed for a street ridden bike to add some fuel. If you are concerned about AFR the way you seem to be then other more sophisticated tuner choices and a dyno tune would be your best choice.

As far as setting pot#1 at 1800rpm, in this area the pot effects the low speed to mid fuel delivery and at that rpm, it is easily to detect the engine speed changes that the settings are making. It's not rocket science and I think you are reading a bit much into the picture. The intake has sensors like mentioned above that will adjust for varying loads and throttle positions and compensate with different pulse widths to the injectors (time opening). These pulses are sent out by the ECM and the TFI will modify them to the pre set values that the unit has been set to by the user.

I know you're high on this unit and sell it on every post you can, and that's fine. What I don't like about it is that it's guess work at best. Install it and mess with the settings until it either feels better or sounds better (RPM). Increase the pots to hold the injectors open a little longer. I've yet been able to find an explanation of how to richen up the idle.

Like you said "anyone that knows basics about tuning can set the TFI up where the bike runs the best without using sniffers etc to test AFR." Anyone thats been around tuning bikes for a while wouldn't rely on sound to tune a bike either. Get it in the ballpark, maybe. Tune, not likely. Plugs will tell a little, but not truly reliable in giving a visual of lean/rich based on color. So, back to relying on how it feels and sounds, but not knowing for sure if it's running the way it should. If just getting it close it acceptable, then maybe this unit has some merit. I guess that's up to each person to decide if... close enough...is good enough.

I just don't see the sense in spending 20k on a bike and then relying on a unit that's set up based on feel and sound, which by the way, could very well be different from what you hear and feel compared to what I hear and feel (same bike). Now, if this unit told me somehow that my bike was running xAFR at idle, xAFR at low speed, xAFR at cruise and xAFR when I cranked the throttle...then I'd be okay with that. But this unit tells me nothing. I'm just not really thrilled about the guesswork, or the "it feels better, it must be okay" approach.

 

[Grillfish]

SlimJim: I think your best bet is to go to the HD dealer and get them to install the SERT and dyno it. Then you have no worries.

Ride Safe and Have Fun.