Please define two terms for me - light throttle and limp

Can someone, or several someones, give me a definition of what the term "light throttle" actually means in terms of the amount of throttle that is used?

OK - let me try and explain a bit more. I'm sure it's common knowledge that they say that you can lean your bike out a bit more when using a light throttle (light load on the engine). I'm trying to put that in numbers. For example, does that mean 20% or less throttle? 30%? 40%?

Like I said, I'm trying to do a bit of custom tuning and I want to lean it out a bit (closer to stoic - whatever that term is - you know - 14.7:1) but not necessarily going to stoic (or much over it). I mean, if I can cruise along at 10 - 20+% throttle all day long, why can't I lean it a bit for better mileage?

Also, I've heard of something like "limp along mode" - where the computer stops using inputs and just relies on a pre-programmed map to get you to the dealer. Can someone enlighten me a bit more on that? Does it tend to make your bike run a bit richer than it should?

Thanks.

Light throttle and Granny gets off the line faster than your bike and she's using her walker.

OK - only ONE comedian here and that's me.

I'm talking about cruising here. I can see where one might have been confused.

Now, any serious respondents out there?

I'm not quite sure what you mean. If you let off the throttle, then assuming you have the same parameters in all other categories (load, wind resistance, grade either +/-, rolling resistance, and so on), then you will simply just go slower and your engine will be at the same load for the amount of fuel being used. Which could lead folks to think something strange is going on, maybe the engine is running leaner since less throttle is being used, but really there is just less wind and rolling resistance at the lower speed.

But right along side the less fuel at lower throttle openings, is also less air since the butterfly isn't open as much. Now you could have spots in the RPM range where the computer is actually metering things slightly richer or leaner, but that doesn't seem to be what you are asking about.

Limp mode (most of the time anyway) is usually tied into the timing of the spark. If a bike is equipped with limp mode it will usually retard the spark so pre-detonation does not occur. Sometimes it can be a metering back of fuel, which is also accompanied with secondary butterflies choking back the airflow as well.

For custom tuning, if it were me I would just run something designed to modify the fuel pulses and then have it dyno tuned. Presto, no more guess work, and it won't get any better.

I've had it dyno tuned before - never was happy with it. The tuner seemed to skip a bunch of ranges and I tend to ride with an easy throttle - the same way I drive a car - easy on the peddle (highest vacuum possible). Now, if I could be in charge of the throttle when it's being dynoed, then that might work, but the last tuner I had seemed to think that I wanted it to act like a sport bike and it's not. I don't ride like the tuner tuned.

Let me give some examples from today, hopefully that will explain all.

I'm cruising around town - doing about 35 - 45 mph and I'm only at, say, 15% throttle opening - no lugging. To me, that would be a light throttle. There's probably another name for it but I don't know it.

Another example: I'm going down the interstate doing about 60/65 mph and I'm only at about 20 - 25% throttle opening - no lugging. Again, to me, that would be a light throttle.

In contrast, I've got a nasty headwind and I've got the throttle opened up around 60% - that is not a light throttle opening.

Does that help explain what I'm trying to find out? I can't give exact speeds since I have no way to record them.* I can record throttle position, A/F ratio, RPM and (just for kicks, Lambda).

* Something about my sense of preservation prevents me from writing notes while riding. I don't care how many YT videos show folks doing crazy stuff, not me. I have too much respect for my (literal) skin and body parts.

happytech, I would think with the ctv drive, you would have to open the throttle more to get more response than if you had gears that would allow choosing a better rpm range that would result in better mpg's. Low rpm's do not equat to better mpg.

So you are talking about light engine load which translates to using less throttle.

I still don't know what you are really asking for.

What programmer does your Burgman have on it that got tuned? I know on the Stroms you can do a basic tune with a Yosh box and nothing else, but that is far from the capabilities of running something onboard like a Power Commander.

Right now I've got a PC III USB and a Wideband 2 with the LCD screen. I wish Chris made an autotune but he doesn't and said he probably never will. Oh well - that makes being a tweaker more challenging.

Anyway, that's where I'm getting my readings. It wasn't bad to wire in once I gave up and just attached two of the wires to the wires coming out from the ECM. The only problem there was my wiring diagram and the pin assignment took a bit of experimenting but still accomplished. Now that I know my tach is also off by about 10% (roughly the same as the speedo - actually 12%) I can get a better idea of what the bike is doing. It can hum along all day at 5,000 - 5,500+ RPMs. I think that's about 70/75 indicated (I don't remember - I couldn't take notes) and it redlines around 8,500.

Once I get this set, and I'm getting close to where I want it, then I need to take a trip back up to Colorado and see what happens. The last time I was up there I was dying at altitude. The problem started at 2K feet and just got worse. It's like the altitude sensor (or whatever they call it) wasn't talking to the computer. Ditto when I played around down in Death Valley. Sorry, didn't mean to get started on the tangent. Must be time for bed.

PS: "What programmer does your Burgman have on it that got tuned? I know on the Stroms you can do a basic tune with a Yosh box and nothing else, but that is far from the capabilities of running something onboard like a Power Commander." - did the above answer your question sir?

If I get your line, you are looking for a method to stretch your mileage by leaning out the fuel feed, and you have fuel injection.
In that CCC system, the fuel computer is reading the tach, throttle position sensor, and Manifold absolute pressure adjusted by coolant temp, possibly humidity (some systems have a 'hot-wire' system that collectively figures air density and humidity and temperature of the air through the variable resistance of the heated wire) and FINALLY corrected by the one or two Oxygen sensors in the exhhaust system reading the residual O2 before and after the catalytic perverter.
What you're looking for is a way to adjust the fuel mix for optimum LEAN-side mix.
Yes?
Then you have to alter the computer OR an input to make a difference. The computer would have to have an alteration to the program. The inputs are the easier adjustment BUT you would need to decide when and how much to alter them.
You could change the resistance of the throttle position sensor by placing a potentiometer in line, or a switched defined resistor, or reduce the resistance in the first O2 sensor with a by-pass resistor parallel to it, OR mechanically lean the mix through induction of additional combustion air downstream of the butterflies by way of a vacuum take-off. A cruise-air-compensator used on the early Virago engines might work. It added a small amount of air during steady cruise ABOVE 3000 RPM on both the 750 and 920 engines. Most owners never knew what it was and took it off in trying to simplify the system. You could find one on E-bay and try it. The key to not screwing up the system would be an EGT sensor to monitor the temp of the exhaust to prevent over-lean spark knock.

Of course, with that automatic, what you really want is a lock-up when it gets to it's highest (lowest numerical) ratio.

WHEW! I didn't mean to cause this much confusion.

1. I have a bypass installed in the O2 system so the ECU thinks there's a working O2 sensor and that it's reading LAMBDA = 1;
2. The PC III USB is adjusting the fuel injector either +, 0 or - depending on what I have that range set to;
3. I'm running a wide-band O2 sensor that came with the wideband 2 kit from Power Commander and that hooks in to an LCD display that's wired in to the negative coil, the throttle position sensor ground and positive, etc. so that I can see my throttle position, my A/F-Lambda and RPMs in real time. (BTW, as with the speedo, the tach is also off about 10%.)

So, going by TPS (throttle position), would a light cruise be something between, for example 5% and 25% of maximum throttle position opening?

yes


leaning it out more than it was already will cause it to burn more fuel and just plain burn up the engine.

if you are a better engineer than the Suzuki engineers you already knew the answer to your question.

the mid 80's Kawasaki voyager 1300 (mega land yacht) had a buton that did what you are wanting to do, that the burgman already does.
it was "jetted" pretty good in normal mode and when up to speed on highway you could push the "cruise" button that was not a cruise control, but switched maps in the ECM to a leaner one.
it was recommended that it only be used in cruise because it caused lean run issues at lower speeds.
the bike had a instant mpg display (among others it was a advanced bike for its time) and switching to the lean mapping was good for a couple mpg at interstate speeds.
the one thing the voyager was missing was a O2 sensor.

the burgman was made to constantly control the ratio and keep it at the most efficient ratio for economy and emissions already and you and eliminated that thinking you can do a better job than the computer can?
everyone else puts that stuff on so they can run richer and boost power, not leaner.

Actually, in some cases, I have boosted power.

I'm now almost sorry I asked.

I think Leon hit the nail on the head if in fact you want better MpG. But.......a much leaner burning engine will run excessively HOT with the ensuing melting pistons, etc. For a burgman, I also say leave it as Suziki designed it. Just my .02, YMMV. Good luck!

Before I started messing with this (I still have the last tuner's maps) I set a zero map and noticed several issues. I've tried to get Suzuki to talk with me about them but gee, the dealerships don't want to mess with my machine. I still wonder if the thermostat either opens too soon or never fully closes.

For example, the low end TPS openings (2 - 10%) run very rich - somewhere around 11.5 - 12.5:1+. That's fine, but when that's the range that you're riding in a lot of time, it can easily foul a plug on these machines. Between that and the less that optimal air intake design (3" off the flippin' road and draws in a LOT of road junk to foul an air filter in a heartbeat), I can foul out in a hurry. I've set those low ranges and RPM ranges to a bit leaner and using a light touch on the throttle I'm not expecting to have a problem. In fact, my Burgman feels and acts peppier. I, ahem, tend to ride a bit past the speed limit when I lean it out a bit. Again, a turner isn't going to tune the way I ride - see my previous post.

Another example, going down the highway I again can keep a light hand on the throttle (remember, I'm watching a monitored TPS/RPM/A-F ratio settings so if I'm running a bit leaner than say, 13.8 then I'm not worried about it. When the throttle starts opening, then I start making the mixture more and more rich - all the way up to almost 12.5 at full throttle.

Actually, I was planning on making some test runs today (my LCD display logs the runs on and SD card) but I've been grounded by a nasty two ear ear infection.

If I do notice what may be a problem (done that before) I can always plug in my little 9-volt battery and override the mixture settings on the map in 2% increments. I ride easy most of the time - thus the original question about light throttle.

Actually, I'm shooting for what the MPG meter says - more is better but I'm NO WHERE NEAR one of these hyper-miler folks. If I wanted a machine with gross power, I would get one. I'm just trying to make mine the best it can be.

Oh yes, on my last trip, when I was in Colorado, I could barely hit 60 mph indicated and had to close the throttle a bit to do that, and I was running the O2 sensor without the Power Commander. In addition, my poor plug looked so white - not really burned/eroded, but white.

I also keep a check on the plug color and as long as it's close to light brown/tan, then I'm not overly worried about leaning out the mixture. I'm from the school that reading a plug, especially if the O2 is not active, is a good idea when you're tweaking.

I couldn't read the last few posts so I'm just going to say my part.

First Id you are looking for a good tunner take it to steve kan in Lewisville @ prt performance. He's really good I've taken my race car to him for nearly a decade now.

Anyway, what you are seeing is am x y graph map. Horizontal is usually rpm and vertical is usually MAP/Kpa/psi (manifold absolute pressure, kpa and psi are basically imperial and metric pressure) the pressure is the load which is usually controlled by the amount of throttle given, ie 10%-20%.

Don't install an egt sensor, that is old technology and the use of a wideband negates the need for that sensor, which is what was used 20 years ago before wb02 was invented.

what you are experiencing in altitude is not uncommon when you have an aftermarket ecu installed. It is similar to what was experienced in the old carburetor days with the need of refining your jets. Unless your ecu now has a map for altitude adjustment (usually labeled as a trim map) you will have to create a map for that which can't really be done unless you are there running asset that time