Moving Air Sensor Bad Idea? Probably... - Kawasaki Vulcan Forum : Vulcan Forums
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post #1 of 17 (permalink) Old 10-10-2012, 03:09 PM Thread Starter
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Moving Air Sensor Bad Idea? Probably...

I am guilty of moving the air inlet sensor on my classic. I have been tempted to move it again on my vaquero to the front of the fairing. However, this will just be an exercise in "doing stuff I read on the internet" more than rooted in any facts. I have seen absolutely no factual information on this forum related to this mod. I myself am guilty of suggesting this move out of ignorance. When I made the move on my classic the bike seemed to run about the same as it did with it in the air box. If there were changes I have no data to back up just how this move "tricked" the ECU into dumping more fuel into the bike. Here are some questions I cannot answer yet I went ahead with this mod mostly out of desperation to try anything to make my classic run better.

1. Why would I want to move an air inlet sensor from the most optimal place it could be located where the actual temperature of air entering is read just before entry? If this is to trick the ECU into dumping more fuel in why would I want to do that? I know, I know, to make it run less lean right? Leads to number 2...

2. Why would I want to make the ECU run less lean by tricking it that my incoming air is cooler than it is? What kind of correction/adjustment range does the ECU have? How do I know if I'm taxing the ability of the ECU to dump compensated amounts of fuel based on ambient temps?

3. What happens when I'm riding my bike in wide ambient temp ranges like 40 degrees? It's not 40 degrees very long where the inlet sensor is. What effect does fooling the ECU to think that air entering breathed in by the motor is always 40 degrees. When the motor has been running for a while?

4. Does the ECU ever figure out that it's been fooled about the inlet temperatures and begin to ignore values such as constant 40 degree temps?

5. It seems whatever advantage I would have over a richer running ECU would be null once any form of fuel processor was added. In my case I'm using a FI2000r which is older technology. I would assume I would want the ECU "on my side" and as accurate as possible rather than having it dump more fuel in the bike and then simply adjusting my Cobra down to try and compensate for the increase in fuel added. This defies what little logic I have.

6. What effect on the ECU/motor does turning a sensor designed to read INLET air temps into one that reads AMBIENT air temps have mid/long term.

Nobody has a clue just how the ECU works on our bikes. Kawasaki has that under lock and key. We all assume the they run lean and there has been enough evidence to support that. But where? Certainly not in the upper RPM range as evidenced by Cobra's lack of adjusting the 3rd pot.

My vaquero has given me VERY consistent FI performance. No lag, no hesitation, etc. I have the occasional popping on decel that I believe can be eliminated with a PCV and map. All leaks have been eliminated.

I have to admit this is the first mod I did without any actual knowledge of what I was doing. I mean, I have not the slightest clue when you get right down to it. Basing a mod off others saying "It runs better", "I can tell it now runs richer." and then providing no Dyno numbers is wishful thinking.

I did find a few places that discussed IATs and this one on an automotive board provided some data and interesting analysis...

For now my sensor will remain an air inlet sensor rather than a ambient air sensor. Maybe someday someone will do a study on how this mod really effects what's going happening on our bikes. Or any bike for that matter!

It seems to me the most consistent readings would be where the sensor is now. The ECU compensation on those really hot or cold days would not be nearly as great due to the radiant engine heat which is always fairly consistent plus or minus ambient air. I'm not sold on consistent temps when moving it making any real difference. No one knows what the ECU can account for. If I'm riding in 30 degree weather my sensor is always reading 30 degrees rather than someplace over 200 degrees which I have seen in the air box using an infrared thermometer. The first person to tell me exactly how this ECU reacts to 170+ degree temperature changes on a warm motor could only be a Kawasaki ECU engineer.

Last edited by 1700Classic; 10-10-2012 at 03:22 PM.
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post #2 of 17 (permalink) Old 10-10-2012, 06:32 PM
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Dont move it. I did on my 2011 Nomad. Ran ok in wisconsin, but lost 3-4 mpg. Did'nt really notice that it ran any better. That was the least of the problem. I took a trip to the black hills SD. Being in the high altitude. My bike could not get out of its own way. I had no power to climb the mountians. Was in the 70-80 temps outside. Racnray told me it was running to rich and the timing would retard and i was useing premium fuel which the engine could not burn. I was down to 27 mpg at times and 32 at best the whole trip. Put it back in the airbox when i got home. My mileage is back to normal. My bike is stock other then Racnrays throttle mod.
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post #3 of 17 (permalink) Old 10-10-2012, 08:51 PM
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For the most part I agree with 1700Classic.

There was only one time when I was tempted to move the air temp sensor, and that was when I briefly experimented with a "Stock Air Cover" BAK (I have since gone back to the stock intake and couldn't be happier).

The aluminum backing plate on the BAK quickly got hot and remained so until I did some highway miles to cool it off with air flow. When the backing plate was hot, however, the bike was extremely sluggish. Especially after a ride and restarting the bike...with the bike sitting and the plate absorbing engine heat, the Air Temp Sensor got so extremely heat soaked that the sluggishness described earlier got even worse.

At the time, I didn't have a fuel manager, so moving the Air Temp Sensor may have helped. Getting it to a position off that "Aluminum Hot Plate" couldn't have hurt.

However, with the sensor where it belongs in the stock air box, away from any hot metal plates, the bike has plenty of snap and runs more consistantly.

Last edited by Vulcan Hammer; 10-10-2012 at 09:42 PM.
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post #4 of 17 (permalink) Old 10-10-2012, 09:18 PM Thread Starter
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It took me quite a lot of fooling around with the first pot on the Cobra to get it to a tolerable point on the classic. Shortly after I moved the sensor and a whole new round of tweaking the first pot resulted. So it certainly did something. I never found a satisfactory setting on the Cobra with the sensor relocated. I assumed since I had issues with the classic that this was just one more problem with the bike. It never occurred to me that doing stuff you read on the Internet that has no factual data behind it may be a bad idea. Based on my experience I would assume moving the sensor changed the fuel at some point in the power band. Where? Who knows! How much? Beats me! All I know is popping increased and I was back at adjusting my fuel processor. I ended up adjusting it down under the assumption that I was running richer.

Jp your experience lines up with other things I've heard. When I moved mine I only ran the bike in 80-95 degree ambient temps on mostly flat grounds. I have a suspicion that the air inlet sensor is where it is for a reason. It's not an ambient sensor. I don't think they simply put these where they are as an EPA conspiracy. The only way to have true control over rich/lean situations is with a power commander on the dyno. I certainly don't understand moving the sensor AND running a pc custom map. Why not leave it alone and run the custom map?

This may be a trick to richen up the mix but how can it be advised with no knowledge of how the ECU behaves with such a change. I hope nobody did this based on my previous endorsement. Until I see DATA suggesting otherwise my OPINION would be to leave the sensor alone.

2011 Black Vaquero
V&H Slips, Thunder Stock Air, Cobra Fi2000r
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post #5 of 17 (permalink) Old 10-10-2012, 09:39 PM Thread Starter
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I can see your thought process as the aluminum BAK plates do get warmer than the stock box as verified with my Fluke infrared thermometer. That situation is similar in that how would an increase in radiant heat effect the ECU? Would it be enough or negligible and within the ECU's compensation bounds? I wonder how sensitive the IAT is when sending temps back to the ECU? I lack an understanding of what temp ranges trigger some sort of communication with the ECU.

I still have the stock air box on the Vaquero but have the thunder 51010 in a box left over from the classic. I'm still undecided about whether or not to put it on. Of course there is the intake noise. Then Bob the Amsoil guy got in my head about the dramatic increase in dirt using K&N filters. So on the one hand you have voices telling you these engines need to breath. On the other you have people saying K&N filters couldn't filter an asteroid. I am very pleased with how the Vaq performs with slips, Cobra box, and stock box. If I do end up putting the BAK back on I will be leaving the sensor alone.

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V&H Slips, Thunder Stock Air, Cobra Fi2000r

Last edited by 1700Classic; 10-10-2012 at 10:08 PM.
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post #6 of 17 (permalink) Old 10-10-2012, 10:02 PM
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Originally Posted by 1700Classic View Post

I still have the stock air box on the Vaquero but have the thunder 51010 in a box left over from the classic. I'm still undecided about whether or not to put it on. Of course there is the intake noise. Then Bob the Amsoil guy got in my head about the dramatic increase in dirt using K&N filters. So on the one hand you have voices telling you these engines need to breath. On the other you have people saying K&N filters couldn't filter an asteroid.
Since you are steering your thread in that direction...

I'm now of the opinion that many who rave about their BAK's are influenced to at least some degree by a placebo effect or the power of suggestion. It sounds louder so it must be performing better, right? Not always...

You cannot dispute RACNRAY's charts showing that peak power increased, but that is only in the very top end with wide open throttle. Who rides at WOT all the time?

My brief experimentation with a BAK was all I needed to show me that my bottom end suffered. Even with the RACNRAY Throttle Mod, it seemed I had to crack the throttle more with the BAK to get meaningful acceleration. The BAK seemed to behave like a turbo that had to spool up before it produced power. And then there was the obnoxious noises it made...

At least for me and for my type of everyday riding, the stock air box has better low end torque and more predictable bottom and middle range acceleration.
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post #7 of 17 (permalink) Old 10-10-2012, 10:25 PM Thread Starter
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And that comes right back at least in part to that magic box the ECU. I have quite a bit of experience with the 09 classic. I put a BAK on later in ownership expecting some real seat of the pants increase in torque. Wrong! The difference between the stock box with K&N and BAK was not felt in seat of the pants riding all other mods aside. In fairness it was never dyno'd so I cannot comment on what it actually did. What I can comment on is how much better the vaquero rides all the way through the power band seat of pants than the classic did. Is it the fact that different bikes of the same brand just make more power. Is it the different gear ratios on the Vaq? Is it the documented fact that the ECU is different on these bikes and produces peak torque later? Something else? I have no idea. The difference is enough where I'm considering the BAK to see if it wakes it up or not. Many Vaq owners have had positive things to say with some dyno numbers to back up the BAK.

I'm looking through my shop manual now to see if I can gain anymore insight into the ECU questions I have. I would email someone at Kawasaki with my questions but they probably wouldn't answer how their ECU works.

I could see this trick possibly helping if the air getting sucked into my bike was at ambient air temp but that's assuming I knew the ECU calibration was cool with this!

2011 Black Vaquero
V&H Slips, Thunder Stock Air, Cobra Fi2000r

Last edited by 1700Classic; 10-10-2012 at 10:49 PM.
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post #8 of 17 (permalink) Old 10-11-2012, 08:39 AM
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Hi guys. I have been following this subject as well since the purchase of my 2012 Voyager. I am stock except for Rays throttle mod. I HAVE been considering two mods to my bike, but am hesitant on the one. The Cobra Fi2000r. I ran it on my last bike and I did like the differance it made in performance (also had exhaust and K&N stock replqcement). I also liked being able to tweak the pots myself to gain in my opinion maximum throttle response. My question here though is, Will the Cobra make a differance on these bikes at all with everthing else stock ie. exhaust and intake? My other question, maybe more a ststement, I have always used a K&N stock replacement filter with just a mist of thier oil spray on it. Again in my opinion, this would catch the larger particles that might get by compared to the stock paper filter. I always thought that more air intake was better. Going back to the days of flipping the lid on my 4banger Vega in the 70's. At least it sounded better So, am I wrong in this assumtion of more air is better? Are these two mods a waste? What are ya'lls opinions on this?
Thanks, Frank

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post #9 of 17 (permalink) Old 10-11-2012, 09:05 AM
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Well, to rehash my opinion from earlier in this thread, I personally feel that the 1700 BAKs (Big Air Kits) are "more Sound than Substance". There are a few on this forum and the Vulcan Bagger forum that have removed the BAKs because they are so hard to live with...primarily because of the noise, but also because the real-world performance increase is either exaggerated or unsubstanciated (at least with just stock exhaust; BAKs may only be truly effective combined with aftermarket exhaust).

Sort of like your Vega with the inverted air cleaner cover. By the way, I had basically the same car, a '73 Pontiac Astre, which I try to forget about
It had a fully sealed air cleaner shell with non-serviceable filter (one of GM's worst ideas) and you could not simply invert the cover to let in more air. Was yours, perhaps, the later Iron Duke 4-Banger?
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post #10 of 17 (permalink) Old 10-11-2012, 10:08 AM
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Fuel injection systems on our skoots are pretty simple and relatively archaic as compared to what cages have. FI systems rely on signals sent from the various sensors to the ECU. These signals are based on either voltage levels or frequency. Ambient, intake and coolant temp sensors are infuenced by the temperature of the medium it is measuring, and a voltage signal is recieved by the ECU. Sensors such as camshaft position and crank speed sensors are responsible for their frequency of voltage signals sent to the ECU. Throttle position sensors send varying voltage signals to the ECU that represent how the throttle is being operated. Pretty simple stuff.

It is erroneous to state that an ECU can be "tricked or fooled" as it does not have a mind. Living breathing creatures can be "fooled", ECU'S can only take in the signals from the sensors, match those signals to the internal mapping parameters and send out the map's pre-determined signals to the injectors and ignition system.

The EPA does it's emmission testing in a VERY LIMITED rpm/throttle position area. This is normally a "cruise mode" which would be representative of a vehicle "cruising" down the road. The rpm/throttle positions affected by EPA emmission requirements are usually up to 20% throttle, the rpm range is detirmined by taking the rpm at which the engine makes it's peak H.P., divide that by 2. On the 1700's they make peak power @ 5200 rpm, divide that by 2 and the range of rpm that may be "compromised" extends to 2600 rpm.

I have seen many stock skoots, and also on these 1700 the a/f ratio is a bit rich outside the areas affeted by EPA requirements. On the Vaquero we installed tri-ovals and documented the change in power and torque and was also able to see the a/f ratio. It was too rich above 3000 rpm, and on many sportbikes we see the same richness on completely stock bikes.

Moving the a/t sensor is extremely benificial on skoots with ram air intakes. When the ait sensor is located in the airbox above the engine and sealed behind lots of bodywork, the sensor experiences "heat soak", yet the engne's air supply is from outside this area, the air temp the engine inhales is closer to ambient than what the sensor is reading. On the newer R1's Yamaha has located the a/t sensor to the front in one of the ram air tubes, pretty much where we have relocated sensors for years. I started relocating a/t sensors on ram-air sportbikes about 12 years ago.

On the 1700's the stock intake supplies relatively hotter (as compared to ambient temp) air to the engine so keeping the a/t sensor in it's stock location may offer the best performance and mpg. On skoots with BAK's there is usually a benefit to moving the a/t sensor to another location as there is a reduction in intake air temperature with most of these kits.

Thes 1700's are no different than other skoots, but Kawasaki's decision to utilize a single spark plug in such a huge bore was certainly a mistake on their part, but was probably necessitated by asthetics and manufacturing costs. Two plugs per cylinder on big bore engines offer superior combustion characteristics, allowing better performance, reduced emmisions and minimizing how the a/f ratio has to be compromised( i.e. "leaned out" ) to meet those emmission regs.The plug the 1700's use is indicative of how a spark plug is designed for a particular engine. When we have sufficient space between the ground electrode and the piston dome we always utilize "projected tip" plugs in place of standard reach plugs found in most skoots. By "lighting" the fire deeper in the combustion chamber we see better performance. The 1700 use an "extremely" projected tipped plug which is their attempt to make up for the decision to use a single plug.

These 1700's are just about the simplest skoots we work on, but in many ways Kawi has made decisions that I see has and is still causing problems for some.

My skoot runs absolutley flawlessly with my own design of BAK, highly modified V&H 2-1 exhaust and custom mapping. My a't sensor was relocated about a year ago. My skoot makes impressive power and on a ride down to Key West is saw over 50 mpg.I consistantly can go over 200 miles on a tank of gas, and that is on 87 octane, the cheaper stuff!!


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