Air Temperature Sensor - Improving Engine Performance?
 

Did I read where some board members added a resistor to their air temperature sensor to simulate riding in colder temperatures? The outcome was an increase in fuel richness and a change in engine timing?

Is my understanding correct? :confused:

If it is correct can someone provide a description and pictures so an electrical/electronic novice would be able to select the correct resistor and properly install the modification? Would any one with real world experience want to describe the change is performance?

Thanks!

PS - I have a 2004 R1100S Twin Spark

Oh, boy................don't need another thread on this:

http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/495368-power-frk-product-review.html

Instructions on how to do it would be very welcome!

Have these been posted elsewhere?


It would be really useful to have the info regarding pin outs, model/part numbers for the connectors, and which resistors are needed.

From glancing at the lengthy mobius "FRK" thread it is clear that OwenM has spent a considerable effort on this topic. Although I've read his description on how he did it, I'd love to have more DIY info...is anything documented anywhere?

Bosch spec sheet is all you need. But only you can do the next step: just pick the temperature you think suits your bike as modified. Or ask Foster.

"Pin out" is two pins. Wire resistor in series with either wire or if you remove the sensor, between the leads from the ECU. With a big resistor, just won't matter much to the "temperature" if you choose to keep sensor in the circuit or not (but size of resistor will be a bit different).

Can't get much simpler.

if you know enough to take if from there, then you can take it from there. But if you don't, you shouldn't try.

How many times and for how many months have I posted this same information?

Which pins on the connector??? Are there only two showing?

The sensor only has two wires connecting it, a resistor needs to placed in series with either one, it makes no difference which. A 10k ohm resistor should be enough but you may need to go higher depending on your bikes needs. The simplest and cheapest method is to cut one of the wires in the harness, solder the resistor in place and insulate it will heat shrink or tape. If you really don’t want to cut a wire you will need a male and female pair of connectors (they are the same type as used on the fuel injectors), this will enable you to put a resistor in series with one wire and simple length of wire in series with the other. Another alternative is to use a 20k ohm variable resistor (pot) in place of the fixed resistor; this will give you ample adjustment to cater for most needs.
I should get around to implementing a more permanent setup for my RT, when I do I’ll take photos and post.

How much difference does a fake FRK make? :D Well that depends on your bike, anything from almost none to a significant amount, it depends on how well your bike is running now. On my standard RT the difference was insignificant, but with Lennies sprockets installed there was a noticeable improvement.

Sorry Ben. I must have missed that.

Excellent info. Thanks!

The connectors have been ordered.:p

Bosch Type EV1 Injector Connector MATE Connector Pigtail $5.99
Bosch EV1 Type Injector Connector Pigtail Push to seat $5.99
Shipping $ 4.90

Total so far $ 19.38

Yikes!

Adjustable pots have three connectors! Is one not used? What do the three connectors connect to?

The connections are shown right on the side. Full Resistance is between the far pins. The center offset pin is the slider.

You will want to connect between one end and the slider.

Thanks Bill!

If I understand this theory correctly, Andrew and I are just coming into prime riding weather!;)

Andrew -

Great moves.

With those connectors (forming an "extension cord" configuration with the sensor), you might retain some cold weather function, if the external resistance ends up being low.

Pretty inexpensive connectors. Hope they are right ones. Length of wiring not critical, but might be helpful to add a ferrite bead taken from an old computer cable.

It is proper practice to connect the slider lug to one end lug in this kind of application (won't affect resistance).

You have to measure resistance each time you set it and so you have to disconnect both plugs. With that pictured pot, you won't be able to eyeball the setting and re-setting, esp. since you are likely to be choosing among resistance values that are low and close (on that pot), too bad/ You have to think of human factors when humans are involved and maybe you can get away with a tiny paint dot to mark the settings.. esp if you can do this beforehand.

After you post your preferred resistance values, people can buy pots in that range (plus maybe 30%) or use a fixed resistor plus a far smaller, eyeballable, pot.

Based on my Techlusion tuning experience (a little scoot circling Lake Superior), it might take 3-5 tries to get the right setting. Since this is such a crude approach, it is likely to be different from different routes and even bad on some. So to reduce your testing confusion, optimize for one route before trying on another kind of route. An AIT spoofer might be a suitable mod for people who do nothing but ride two-lane twisty country roads in warm weather but less suitable for guys in Boston with much more variable routes and weather.

If you can figure out any way to see if spark timing is influenced by adding the resistor, that would be great.

Good luck.

Andrew, maybe you could find a 3 position switch and apply full partial and off positions for the added resistance. What a great test bed that would be on the dyno.

Andrew is going to need a dyno, a large range of variable resistors and a great deal of time to make anything that resembles an FRK.

Perhaps. I'm just trying to richen the 3 - 5k rpm range where I spend most of my fun time. If it works, great. If not, Ill have wasted $20.00 that I should have put toward sprockets and beer.

The FRK is clearly much different , being much more well thought-out and involved.:D

Nope. That's wrong in almost every sense.

We are talking of a single variable: temperature (AKA resistance). That's pretty straightforward to track, eh.

Little that an inertial dyno can tell you about the sort of benefits you might get from gross changes of the sort BMW built-in to compensate for ambient temperature and which Andrew is hoping will track with the mods on his bike.... lucky if it does. Inertial dyno curves might bulge here and there, but not likely to find orderly and interpretable results or bulges big enough to be worth bothering about. Test rides, on the other hand, might show the sort of benefits that others have claimed. Same is true for Techlusion.

It is no trick at all to duplicate an FRK: with some testing, you can hit the same temperature set point. The trick is to find a temperature that kind of tracks what your engine wants. That's hard (or impossible) with a single variable. With Foster's FRK, he mails you replacement FRKs (each FRK has a different temperature.... if your unit is too rich, he mails you a warmer one) till one suits your mods and your riding style, as we have seen. With a pot, you twist the knob up and down till you like the results. Then you measure the resistance and post here (including details of your other engine mods, state of tune, test ride route, etc.).

when you guys are done with this thread we will ask Roger to splice it on the end of the FRK review, where we just had 600+ posts worth of the same discussion.

give it a rest dude ;)

Right you are Bill!

It takes a lot of data to analyze and perfect!

R&D is not riding around a lake!

Without repeatable verifiable empirical data you can not quantify anything!

The Dyno is the only way you can quantify!

Then you can take a ride around the lake with a portable 5 gas analyzer/data logger to proof your work.

Ultimately, only then you can have the data needed!;)

Ben, please bash the FRK in the FRK thread! Not here!

Dr. Foster, please stop with the spam! This thread is not about the FRK!

This is not spam!
 

Sorry Andrew,

I see no spam here!

Just good advice.

Best!

Andrew, I hope you follow this to some kind of finish by taking up Robert and his FRK's return policy and actually comparing what you have done with what the FRK can do.

Now there's a good idea. Owen and Andrew do the very best temp sensor mod they can using whatever resources they care to throw at the project. Evaluate. Then, get an FRK and evaluate. Good news is if you don't like the FRK, send it back for a full refund and all you've invested is your resistor research. I'd be all ears.

+1 to that. I don't see how you could tune it, without at least an exhaust gas analyzer though. We just bought a new one at work that I use on boilers. ($5000).

Seat of the pants is no way to tune an engine. It's just asking for a melted down piston.

Adding a resistor in series with the temperature sensor can never make the bike run leaner than it would without it, you can only go richer which will not melt pistons or cause engine damage.
If you go too rich you will feel it, but it appears there is just not enough trim factor available with changes in temperature sensor input to give a significantly over rich condition.
Using a conventional pot which gives a visual indication of what setting is in use rather then the multi turn trim pot shown in the pictures above is a better idea until you work out what setting to finally use. Remember that you must allow 30 seconds or more for adjustments to take effect as the temperature sensor input is very slow to react, you can’t just turn the pot and get an instant reaction.

I see no need for a dyno or gas analyzer for set up unless you are only interested in numbers; most riders want a setup that feels the best to them for the way they ride. You are more likely to find that point by experimenting with different settings your self rather than using a predetermined setting with a FRK.

If you have a GS-911 code reader or go to your dealer/mechanic who has the factory diagnostics tool (GT1) you can see exactly what temperature the FRK or your resistor is sending to the ECU. If you have a FRK plug it in and measure what the ECU sees, then plug in your home made adjustable FRK and dial in the same temperature reading, you have then established what resistance is required to do the same job as the FRK.
Some mechanics may offer to do this for you free of charge just out of personal curiosity, but even if they don’t it only take a few minutes so it cant cost much.

Picture of GS-911 data showing input intake air temperature (21 degrees) as seen by the ECU on right.

http://www.hexcode.co.za/products/gs...ts/904/904.png


GS-911 site.
http://www.hexcode.co.za/


Personally I would much rather spend $299US on the GS-911 than $293US on a FRK.

The goal of this project is not to prove that I can make a cloned FRK, or to discredit anyone (either those in the pro-FRK camp, or those few vocal anti-FRKers). Dr. Foster insists that his devise is much more involved than a simple resistor dongle. I’m willing to take him at his word. I don’t have a dog in this fight either way. If it works, great. If not, Ill probably just live with my flat spot and move on to something else.

Noting that, there are already accounts on the web from FRK owners that have compared their FRKs to resistor dongles. There wouldn't be much that I could add...

I had the pleasure of riding X-Triple’s BCR that has the FRK installed, and came away extremely impressed. It was buttery smooth from idle all the way to the rev limiter. Also, for the few seconds that I was behind X-Triple on his BCR, there was no overly rich smelling exhaust smell. It seems perfect. The FRK is a great product that works.

I am more than willing to document one version of how a resistor dongle might be built, and will provide as much seat of the pants feedback as I can - but I am not really prepared (nor committed) enough to do a full comparison between the two. Also, I'm not sure how valid any test between the two would be without any hard dyno figures (which will inevitably be demanded). Again, I'm just trying to make the bike more rideable within a particular rev range, and couldn't begin to address all of the issues that the FRK portends to improve on.

Regardless, I am more than willing to send the dongle to anyone that might want to invest some time in comparing the two.




I will be employing Tuning 2.1:D

I have access to a GS-911, and will initially calibrate down to -25C (I think - Ill verify this later).

I went shopping today: I got a mixed bag of resistors, a 10 ohm pot (single turn, with fancy knob), and a hobby box. Now all I need are my Bosch connectors to arrive,...and some beer.

Is it German or Belgan Beer!
 

Greetings Andrew,

I admire your enthusiasm. I really do!

However, I think that you have been misinformed.

Owen - You mean parallel don't you?

Definitely not, I said series and I meant series, using a resistor in parallel with the temperature sensor will give a lower overall resistance and make the ECU think air temperature is high thus causing a lean running condition and possible engine damage, and we would not want that now would we.:eek:

Anyone would think you are deliberately attempting to lead people astray there Robert.;)

I do hope that’s a typo, you need a least a 10k ohm (10,000) lin pot to get about -5C, a 10 ohm pot will do nothing.
If you want to simulate -25C a 20k or even a 50k ohm pot will probably be required.

Since you have access to a GS-911 can you do some testing and let us know what value resistance is required to get the ECU to see -25C without the temp sensor in circuit.
Or if the temp sensor is in circuit the required resistor value and current ambient temperature (with the engine cold).

It is not likely that many bikes will need so much fuel that simulating -25C will be required, but it’s useful info none the less.

I also wonder how low a temp the ECU can accept before it bottoms out and won’t go any lower.

Wrong!
 

Greetings Owen,

Don't do this at home...

I did not see that you are including the IAT sensor and not eliminating it.

Key word "Dongle".

In that case SERIES is the way!

Thanks Mate!

Yes. That's a typo! The 10K pot and a 10K resistor should get me to -25C. If not, Ill just add more/different resistors. The pot is only temporary.

Why is ambient temperature important?

I was only interested in the air temperature at the time you where taking measurements because the temp sensor is adding its resistance along with the resistor. If I know the temperature I can figure out approximately how much resistance is due to the sensor if you tell me what value resistance you are adding to the series circuit, does that make sense?
What I want to know is what is the total resistance (sensor plus external resistor) required for the ECU to see -25C.
The sensor on my bike reads about 17k at approx. 0 degrees C, I have not tested it to lower temperatures yet and a deep freeze is only about -18C.

That does makes sense. :cool:

I've been bench testing the pot that I got, and am fairly confident that I can accurately measure 0 - 10k to the 1/100ths. Beyond 10K, I will add a fixed 10K resistor in series. The pot appears extremely accurate and exhibits consistant, repeatable results.

I will chart resistance all of the way down to -25C. (edit: and beyond).

Of course, I will be converting all of my results to Fahrenheit (because metric hurts the melon, and is just silly).:D

all gas laws relating temperature, pressure and volume, use a temp value in Kelvin, neither Farenheit or Celsius will work for these calculations. If your result isnt linear, that will be why

I second the idea of letting the truly technical guys explore and trade facts.
The conjecture stuff will be tossed. Thanks to Owen and Andrew etc for keeping it real.
Interesting.

Some suggestions:

Wire the fixed resistor in, but keep the ends accessible so you can jumper them with alligator clips. That way, you have the advantages of both a 0-20Kohm range and a eyeball readable 10kohm pot. Unless your bike is highly modified, I'm betting you won't end up near 20kohms.

Given the challenge of doing A-B comparisons, the trick is to make the switch as quick as you can - even on the run. So I'd mount the pot on your upper triple clamp. If picking up RF is a concern, just short the wires with small silver-mica cap and use the ferrite bead I suggested earlier. Best place for the cap might be the junction of the pot and the fixed resistor.

shreddr - you're right about gas laws, but the ambient temperature trim factors are arbitrary values that BMW kind of thought were about right and they don't follow any "law," Kelvin or otherwise. Likewise, the NTC sensor (and the inverse network inside the ECU) may not be strictly speaking arbitrary, but they are "unlawful."

It may be fun to "track" resistance vis a vis temperature on that GS-gizmo (I'm not sure what it is). But there is no necessary relation between temperature and the butt dyno, because BMW's trim "curve" is an intervening arbitrary variable. Each rider mostly just wants to see what resistance feels right and, if you own a GS-gizmo, you can find out the temperature later on (or just look it up on the Bosch spec sheet... I may have mentioned this before).

I hope that we are not dealing with extreme enough factors were linear deviations relating to temp scales is a huge issue. Besides, I'm not sure that the GS-911 can display in calvin. :D

Ben, it has been reported that the ECU can take 30 seconds (or longer) to register changes at the Temp Sensor, so having a pot that can be adjustable on the fly wont really help (particularly in the early going).

I have a "fun" route near my house that is about 30 miles. My idea is to run the route, get home, and then collect my wholly subjective impressions. At that time, Ill either add or subtract resistance, and then go on another run. It may take a while. Perhaps a dozen runs, maybe (much) less.

I'd guess (after reading various interweb accounts) that something under 20k ohms should get me to -25C. My pot and a fixed resistor should allow no hassle, quick adjustments from 10kohm to 20kohm. Seeing that my bike runs in stock trim, I should be well below 20k ohms of resistance when I'm done. Or not....