Juicebox?

[txknight67]

How sophisticated is the engine management system on the Spyder?

On an automobile, if one puts in performance mods, (ie K&N air filter, duel exhaust with free flow cats, and upsize the tubing) the engine computer can take advantage of them because all the computer cares about is the stoichiometric ratio sensed via the amount of oxygen at the O2 sensor. The computer then "learns" over time how much fuel to inject for the amount of air being sucked into the engine to maintain that ratio. Thus, bigger cylinder, more fuel and air to maintain that ratio....if I am remembering my high school math and physics correctly.

One can put in a performance computer which then can cut the O2 sensor out of the loop and set the fuel flow, spark advance, etc (depending on how sophisticated a system you buy) to optimize top end performance or low end performance depending on the application.

So why does the Spyder need an aftermarket fuel metering system for just the addition of a freer flowing intake and exhaust? Does it not have an O2 sensor or a MAF or MAP sensor?:dontknow:

 

[ataDude]

... Does it not have an O2 sensor or a MAF or MAP sensor?:dontknow:

Yes, yes and yes. However, the O2 is a narrow-band sensor and affects only the lower RPM band... about 3,000 RPM and below. Over that, it's all mapping.

.

 

[NancysToy]

What AtaDude says is exactly correct. Another thing to keep in mind is that it is not always that easy, even with the autos. Depends on the mapping in the engine management system, and the how far the fuel tables were carried out. It also depends on the degree that the engine is "detuned" by the knock sensors, and whether valve timing is variable. There is a reason that so many performance "chips" are sold. Even if they can respond to freer air flow, modern engines are set to run too lean, due to emissions standards, to really get with the program performance wise.

 

[txknight67]

What AtaDude says is exactly correct. Another thing to keep in mind is that it is not always that easy, even with the autos. Depends on the mapping in the engine management system, and the how far the fuel tables were carried out. It also depends on the degree that the engine is "detuned" by the knock sensors, and whether valve timing is variable. There is a reason that so many performance "chips" are sold. Even if they can respond to freer air flow, modern engines are set to run too lean, due to emissions standards, to really get with the program performance wise.

Gotcha. Appreciate the feed back.

Just wanted to say quite a few of those performance chips take care of exactly what you just described. It takes out the lean burn and like you said either extends the fuel mapping or changes it for whatever application it is advertised for. Also many of them take the engine out of closed loop faster than stock when one is accelerating hard....or just takes it out of closed loop on any kind of acceleration. Many auto computers try to keep the engine in closed loop as much as possible so unless one is really on the accelerator, it stays in closed loop. The performance 'puter for my Dakota also took out the fuel cut off at red line.

I bought the performance computer when the OEM crapped out and I could get the performance 'puter for half the price of the OEM. Go figure.:dontknow: Not for any lack of "go" with the OEM after I rebuilt the engine.

Anyway, after reading some of the threads on here concerning just an air filter and exhaust change, it seems like the Spyder needs a performance chip just to even run right for something I consider simple, mild changes. Something I hadn't noticed in all my tinkering on cages. Maybe I was mis-reading the threads.:dontknow:

 

[NancysToy]

Anyway, after reading some of the threads on here concerning just an air filter and exhaust change, it seems like the Spyder needs a performance chip just to even run right for something I consider simple, mild changes. Something I hadn't noticed in all my tinkering on cages. Maybe I was mis-reading the threads.:dontknow:

It is true, to some extent. Part of the reason is the very tight feul management on the Spyder and the narrow band sensor and/or fuel tables. The other part is that this 61 cu in, two cylinder engine, not a big V-8. It is more sensitive to everything.

 

[txknight67]

It is true, to some extent. Part of the reason is the very tight feul management on the Spyder and the narrow band sensor and/or fuel tables. The other part is that this 61 cu in, two cylinder engine, not a big V-8. It is more sensitive to everything.

Gotcha! Thanks again. That about the fuel management explains allot.

Ya know, as far as the engine size, I hadn't really thought about that.pps: And I should have. Small = much more sensitive to airflow changes.

I also have an ulterior motive for asking this question. I am running the Hindle exhaust already and was going to get the K&N air filter, but was starting to wonder if I would induce problems doing that.

 

[bone crusher]

Gotcha! Thanks again. That about the fuel management explains allot.

Ya know, as far as the engine size, I hadn't really thought about that.pps: And I should have. Small = much more sensitive to airflow changes.

I also have an ulterior motive for asking this question. I am running the Hindle exhaust already and was going to get the K&N air filter, but was starting to wonder if I would induce problems doing that.

Get the green filter (more air flow) or even the K&N...either way, it will help the bike breathe more...

Oh, and get the juicebox...you'll love it...it's fun to play with to tweak what you want to do with your bike. I have found that it does affect mileage a decent amount and performance is really affected...

I haven't been out enough in the last several months to really fine-tune it since the update, but I'll get it down sooner or later...I was at about 32mpg before the update, with tons more performance. I'm thinking that setting 4, which controls fuel during coasting, should be turned down to help with fuel efficiency...I am still playing with the numbers though...