Engine Temp Sensor

Just wondering how this affects how the motor runs. I'm wondering if it takes readings until the motor gets warm enough and then goes to closed loop and uses 02 sensors. I also read somewhere that if the oil temp got to hot that the motor would just shut down. Is there any truth to the motor shutting down? Just curious what the sensor does. The more I know the more dangerous I am.

Ride on

Engine temp sensor will have a lot to do with cold start fuel ratio. This will depend on how cold, and how long at idle, and what the Engineers decided that the engine needs to start and pass EPA tests.

Like you said, once it warms up, what ever that temp is or time from start, then it will go into closed loop and just read the O2 sensors. The temp gage feedback may affect spark timing (proly does).

When it gets too hot it will shut off the back cylinder - or is that the 09s?

I have never heard that it will shut the engine down if it gets too hot. That would be interesting to know.

asked yer question to a Harley Mechanic that works at a dealership.
Here is what he said.

The ECM reads head temp constantly to determine which fuel map to use, wheather in warm up, op temp or over temp. There is no oil temp sensor so, no, it wont shut down if the oil gets too hot!

Hey Cardboard:

Thanks for finding out what the temp sensor does. Good to know that if the oil gets to hot that the bike won't shut down.

Kevin

You shouldn't let yer bike git over 300* while runin or sittin in traffic.

sensor

o8xmod,,,just worked on a 05,,,would not idle worth crap,,,up ,down ,,,die,,,so after much tinkering put an old sensor on it and it has ran well for three days ,,,so guy took home and not complained yet,,,,pops point being i think sensor does more than one thin

When a cold engine starts it is in open loop. The ECM uses a preset map. Once engine temp starts rising and the 02 sensors are warm enough and the temp sensor is satisfied the engine will go to closed loop and get signals from all the sensors.

Kevin

Whats the water Temp !
No water in my bike.

Closed loop operation means that the computer is trying to achieve an air/fuel ratio and adjusts the injectors according based the feedback signal from the O2 sensors. You are correct - the O2 sensors have a heater so they can heat up in about 60 seconds. Once the O2 output signal is within range, regardless of engine temp or anything else, the computer can rely on it and control the injectors by it. That's is all closed loop is. A base map is used in both closed and open loop and as the variables change such as throttle position, engne temp, air temp, gas quality, etc. the O2 sensors will fine tune the air/fuel ratio in order to achieve the best emissions. Being to rich causes to many hydrocarbon emissions and too lean causes to many NOX emissions.

Open loop will occur in two ways - when the O2 sensors are too cold like I just mentioned or when the throttle is wide open. Now this second open loop condition is dependent on how HD programs the computer and the ability of the O2 sensors to read beyond the EPA air/fuel ratio of 14.7 to 1.

If the engine needs 12 to 1 air/fuel ratio at wide open throttle then the computer will have to ignore the O2 sensor for that moment if it can't read that rich. Thus going back to open loop. The EPA will allow this because wide open conditions aren't typically used in the test cycles. Your car used to be that way but with better engineering and wider band O2 sensors most cars can stay closed loop at all throttle positions. As far as your HD is concerned I don't honestly know if they do or don't stay in closed loop at all throttle positions. Something tells me that they don't need to ... yet..

To clarify what I meant was that I think most newer cars, as of the last 5 years or so, can stay in closed loop ALL the time - as soon as the O2 senors are hot enough of course. And I think that HD is close loop ALL the time except when at wide open throttle. I think this because the EPA standards are not as tough YET on bikes as they are on cars.

Other than that I am not sure what you are asking.

Here's a little info I found via Google.......
An Oxygen sensor is a chemical generator. It is constantly making a comparison between the Oxygen inside the exhaust manifold and air outside the engine. If this comparison shows little or no Oxygen in the exhaust manifold, a voltage is generated. The output of the sensor is usually between 0 and 1.1 volts. All spark combustion engines need the proper air fuel ratio to operate correctly. For gasoline this is 14.7 parts of air to one part of fuel. When the engine has more fuel than needed, all available Oxygen is consumed in the cylinder and gasses leaving through the exhaust contain almost no Oxygen. This sends out a voltage greater than 0.45 volts. If the engine is running lean, all fuel is burned, and the extra Oxygen leaves the cylinder and flows into the exhaust. In this case, the sensor voltage goes lower than 0.45 volts. Usually the output range seen seen is 0.2 to 0.7 volts. The sensor does not begin to generate it's full output until it reaches about 600 degrees F. Prior to this time the sensor is not conductive.

I agree with this.

This is a good point - and that is why I said that the computer uses a base map to quickly get to certain air/fuel ratios that are needed when you are moving the throttle around too fast for the O2 sensor to respond. So you could say that for this instance the computer goes to open loop. Right?
This is also called "feed forward" in the controls world.

Another good point. But we could add that if you are at WOT long enough - and we are talking milliseconds - the computer could go back to closed loop here and control the A/F again if it wanted to, if the HD Engineers wanted too.

I also agree with your light switch analogy, however at idle or at WOT the computer can still go closed loop if it is programmed to do this. Again, it is a better control over the A/F if the computer chases the O2 sensors. The A/F can get affected by many things and when the manufacturers are reporting to EPA that their engine emits only 4 parts per million hydrocarbons then that means ALL the engines in that engine family that are produced will get 4ppm (within some tolerance) and to do that they need feedback control as much as possible which means idle all the way to WOT if they can do it. (I only use 4ppm as an example. usually the reporting is in grams per mile)

Even if the light switch is on, that doesn't mean it stays at the same brightness. It may wander with voltage or current etc. so we would need closed loop to keep it at the same brightness

Are we having fun yet :roflmao:
I think I need to smoke a blunt to keep up with you PAz :roflmao:

How much difference do you see between the Car 02 sensors and the WB Bosch sensors.

I've had Carbs and TB Both, I will take TB any days over carbs.

TB cranks easier too.

What are they makin that has carbs anymore.

Sleep and work get in the way of life. The boss is not around so I am back. I like this conversation because it makes me think, but remember I am not an expert, I am only trying to help. If you know better than me then by all means let me know. I won't take offense.

I have experience with Ford EEC IV calibration when I worked at Ford back in the ninties. Many things have changed since then but the basic FI and O2 sensor closed loop theory remains the same. So let me say this, the computer processor has functions and maps to read first and then it will look at the O2 signal to dial it in closer and this all happens in milliseconds.

Now you can say that without the O2 sensors (like my 98) that this is closed loop based on the inputs from throttle, barometric pressure, temps etc. but these are inputs for the computer to look up the map and then output an injector pulse width for those conditions and as we know those conditions are always changing. Is this closed loop? Not really since the tables and functions are created with one engine on dyno by one engineer and his testing conclusion (actually a small team of engineers). It does not take into account all the variability of running conditions and manufactuing processes of engines in the real world conditions. For example if you manufacture 100 engines on an assembly line with the same workers, same tooling, same materials and castings you don't get 100 engines that are all the same. Every one will be different and run differently

The advent of the O2 sensor allows the puter to look away from the tables and functions and derive an injector pulse width by the O2 sensor alone. This will bring those 100 engines to run a LOT closer to being the same way. And this is what is meant by closed loop. The loop is closed on the O2 sensor alone until something changes. (I might be stretching on this point though).

I am wanting to switch to carb on my 98 because the Magnelli Marelli FI system is slow and limited. I think a carb would be much better than this. However, the newer FI systems from Delphi are 10 to 50 times faster and more comprehensive then my MM. So these systems I think are superior to carbs.

Chuck, don't get too cocky. You actually do have a computer on your bike I found out. I don't know everything about it but I do know it handles the VOES operation and altitude compensation.

The best thing about all this is that we can breath. I live in LA and you live in Houston. These are two of the worst air quality areas in the nation.

Gotta go again .....back to work :witsend:

Yeah, I checked into the Thundermax and it does sound like a great system to have. I know I can get it from other states, but the price is still $1500 bucks which is down by 300 since I last checked 6 months ago but it is still too high. And that doesn't include the auto tune kit.

This MM has actually been very good to me, but here is my issue. With modifications (heads, cam etc.) you need a PowerCommander or similar. this is just more electronics on top of other stuff that i worry can go wrong. The PC that I have is fine cept I don't think it is retarding spark for the added compression. The taple is there but it doesn't seem to be working. The throttle enrichment function does not work for MM. You also can't upgrade the ignition system for multi spark or better coils.

So I want to upgrade the ignition system and be able to control the spark curve better. Or, at least that is what I hope I can do with the carb and dayton ignition and better coil.

The biggest problem I am having is finding a carb wiring harness. I ordered one from SpeedSupplies.com last month but haven't seen it yet. Tomorrow I will call them. If they can't get it (HD is out of stock and discontinued) I will have to make it. the rest of the parts should be easy to get I hope.