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CVO Technical => Intake/Exhaust/ECM => Topic started by: SIX38 on October 23, 2011, 08:31:45 PM
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On a recent trip out west I noticed that the oil temperatures would climb as I rode at higher elevations, even though the ambient air temperatures were dropping. Question is, is this due to the higher elevation or is it just a result of the bike working harder going uphill to these evevations?
2009 SEUC, ventilator AC, no cat, 1 3/4 Fullsac cores, TTS Mastertune, 90hp/107trq. Dyno'd by JD Cycle in PA @ 300 foot elevation. Bike ran great, just got hotter the higher I went, around 12500 ft max.
Thanks,
Tom P.
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stock they adjust for elevation and the o2 sensors should adjust for the lower oxygen
with a pc tuner they o2 sensors are eliminated and the bike will run with too little oxygen at high elevations
so im wondering what type of tuner you used?
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stock they adjust for elevation and the o2 sensors should adjust for the lower oxygen
with a pc tuner they o2 sensors are eliminated and the bike will run with too little oxygen at high elevations
so im wondering what type of tuner you used?
He stated he's using a Mastertune, so the ECU should be adjusting for altitude. It could be just the climbing that caused the highter temps. Do you use a alot of engine braking when doing the down slopes?
:devil:
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Hmmm, normaly higher altitude means less compressed air => engine should run richer (i.e. cooler) if anything at all.
If it's running hotter instead you will have to look for another cause I suppose ::)
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As the air gets thinner, the higher you go, it doesn't cool the engine as well as it does at sea level where the air is much denser....so the bike will run hotter as it works harder climbing those grades. Fuel has nothing to do with it in this case because I know the tune was done well if Dave at JD's did it, he is a premier tuner without a doubt. When the tune is right the fuel delivery is based on the MAP sensor and the INTAKE AIR TEMP sensor. The MAP sees the altitude changes which reports to the ECM that the air is thinner or denser and the ECM adds or subtracts fuel to match, the INTAKE AIR TEMP sensor sees how much oxygen is in the air....warmer air has less air molecules than cool air so the ECM will add or subtract with the change of temperature. The 02 sensors only keep the AFR on target...it does not control the fuel delivery do to atmospheric conditions. The bike will not run leaner or richer due to the ambient air or altitude....the ECM will adjust the AFR to what ever air the engine is getting at a given time.
Not to worry as long as your bike is not running above 285~290 degrees climbing those high grades....if it is add 2% to your VE tables and that should bring your temps down quite a bit.
Doc
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Hello Doc and others,
Thanks for all your responses. Where else can you get such a wealth of knowledge other than CVOHARLEY?
Yes, Dave of JD Cycle did the tune and like I have said, the bike runs GREAT under all conditions. I was just curious as to what was affecting the oil temperatures. Temps never got above the 270-275 range and cooled down as I descended. Thank you Doc, for your excellent description of what was going on with the ECM. This site is like a Masters course in HD motorcycles!
Best wishes,
Tom P.
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Tom
Oil temps of 275 are extream...I was talking about engine temps. The oil temp should not exceed 230~240 at the most in that situation...but again the thin air doesn't cool as fast as thick air.
Doc
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Hi Doc,
270-275 was the highest temps I experienced, most of the time it would be in the 230-240 degree range. I was running fully loaded and we were driving fairly aggressively, so the motors were getting a workout. But there was a definite link between altitude and temperatures and your explanation make perfect sense to me.
Thanks again,
Tom P.
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Hmmm, normaly higher altitude means less compressed air => engine should run richer (i.e. cooler) if anything at all.
I agree. :2vrolijk_21:
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Hmmm, normaly higher altitude means less compressed air => engine should run richer (i.e. cooler) if anything at all.
I agree. :2vrolijk_21:
No....the ecm sees the engine is getting less air so it compensates and delivers less fuel to maintain the AFR that is requested in the AFR Table.....the engine doesn't run rich with altitude changes or temp changes or air density changes. The fuel will follow the quality and quanity of air keeping the requested AFR in the map at operating conditions.
Yes....the compression is down which makes the power less with higher altitudes but this doesn't effect the fuel delivery.
Doc
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Hi Doc,
that true in open and closed loop?
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Hi Doc,
that true in open and closed loop?
Kraut
Yes it's the same in both.....remember the 02 sensors only report to the ECM what the oxygen is in the pipe compared what oxygen is outside the pipe at the sensor location, it does nothing to change fuel, the ECM has the job of making the changes, so closed loop is no different than open. Bikes that are pre 06 without closed loop capability also work in the same manner. The MAP tells the ECM the altitude change and the ECM takes fuel away the higher you go, and adds fuel coming down that mountain. The INTAKE AIR TEMP sensor tells the ECM the quality of the air....better air more fuel, thinner air less fuel is delevered. The MAP and the IAT work together, as the bike climbs the ECM compensates for the quality of air and quainty of air...... The ECM will delever the air/fuel RATIO that is requested at all times no mater what the altitude is, no mater if the ambeient temp is hot or cold, as long as the VE tables are correct. If the VE tables are off EVERY THING is off.
Doc
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thx, Doc,
always nice to know someone who knows ;)
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"The INTAKE AIR TEMP sensor tells the ECM the quality of the air."
You sure about that Doc1??
If the intake air temp sensor could modify the map for o2 content, why have o2 sensors?? How does a temp sensor measure the O2 levels at any given elevation when it is essentially a "thermometer"?
Not trying to be a wise a$$, just want to know? ???
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"The INTAKE AIR TEMP sensor tells the ECM the quality of the air."
You sure about that Doc1??
If the intake air temp sensor could modify the map for o2 content, why have o2 sensors?? How does a temp sensor measure the O2 levels at any given elevation when it is essentially a "thermometer"?
Not trying to be a wise a$$, just want to know? ???
The intake air temperature is one parameter used to fine tune the mixture. Higher temperature air is less dense and thus there is less oxygen in the combustion chamber. To maintain the AFR the map calls for, the ECM reduces the amount of fuel as the intake air temps go up, and adds fuel when the intake air temp goes down. This along with adjustments for actual engine temperature, manifold absolute pressure (air pressure and load), etc. make up the basic ECM automatic adjustments to the mixture. All of these are dependent on the accuracy of the various sensors used to collect the data for the ECM, as well as the capabilities of the persons doing the ECM programming. This stuff is one big reason why EFI bikes don't need to be retuned for major changes in altitude and temperatures like the old carb bikes did. But it isn't precise enough on it's own to assure compliance with emission standards, since sensors can drift and things like fuel pressure can change over time and air filters can become restricted, etc. So the feedback loop (O2 sensors) adds another adjustment to the mix, measuring the result of actual combustion and fine tuning the mixture again. In more sophisticated systems, there is another sensor after the catalytic converter to make sure the converter is working. Your Harley doesn't have that yet, but I imagine it's only a matter of time before the EPA and CARB start requiring that as well.
Jerry
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"The INTAKE AIR TEMP sensor tells the ECM the quality of the air."
You sure about that Doc1??
If the intake air temp sensor could modify the map for o2 content, why have o2 sensors?? How does a temp sensor measure the O2 levels at any given elevation when it is essentially a "thermometer"?
Not trying to be a wise a$$, just want to know? ???
There is a difference between quality and quantity.
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The intake air temperature is one parameter used to fine tune the mixture. Higher temperature air is less dense and thus there is less oxygen in the combustion chamber. To maintain the AFR the map calls for, the ECM reduces the amount of fuel as the intake air temps go up, and adds fuel when the intake air temp goes down. This along with adjustments for actual engine temperature, manifold absolute pressure (air pressure and load), etc. make up the basic ECM automatic adjustments to the mixture. All of these are dependent on the accuracy of the various sensors used to collect the data for the ECM, as well as the capabilities of the persons doing the ECM programming. This stuff is one big reason why EFI bikes don't need to be retuned for major changes in altitude and temperatures like the old carb bikes did. But it isn't precise enough on it's own to assure compliance with emission standards, since sensors can drift and things like fuel pressure can change over time and air filters can become restricted, etc. So the feedback loop (O2 sensors) adds another adjustment to the mix, measuring the result of actual combustion and fine tuning the mixture again. In more sophisticated systems, there is another sensor after the catalytic converter to make sure the converter is working. Your Harley doesn't have that yet, but I imagine it's only a matter of time before the EPA and CARB start requiring that as well.
Jerry
Very well said Jerry.....I could of sworn I said the same thing twice in this thread.....lol...lol
Doc
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I love this site. What better experts to answer my question but the combined talents of Doc & Jerry. Great information. Simply put, air at higher elevations is less dense and therefore carries away less heat. Engines will then run hotter. I got it.
Being in the HVAC business I should have known this, but having spent my entire working career at less than 1500 feet, the issue never came up. But as they say, one is never to old to learn.
Thanks again,
Tom P.