I'm just curious. How the sophisticated ECU software is to know oil viscosity?
New car, 2014 Mustang 5.0 Track Pack
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Originally Posted By: SteveSRT8
The last line says it all.
The mfgr has PROVED that the engines can tolerate almost any weight of oil by their own specs!
Unless you have the moolah to buy a new Coyote engine out of pocket I'd be sure to use the correct oil.
I see we're on the same page.
The last line says it all.
The mfgr has PROVED that the engines can tolerate almost any weight of oil by their own specs!
Unless you have the moolah to buy a new Coyote engine out of pocket I'd be sure to use the correct oil.
Originally Posted By: KrisZ
I'm just curious. How the sophisticated ECU software is to know oil viscosity?
There are many possible answers to that question. My guess is that it just looks at oil temperature, and if exceeds a preset limit, the ECU limits engine revs, richens the mixture, retards the spark, and generally makes sure that the car is no fun to drive in that condition. Ford probably makes the worst-case assumption that the oil is end-of-life 20-weight and would have the lowest viscosity that could be in the engine. If the engine actually has thicker oil, there is margin built in with that assumption.
I'm just curious. How the sophisticated ECU software is to know oil viscosity?
There are many possible answers to that question. My guess is that it just looks at oil temperature, and if exceeds a preset limit, the ECU limits engine revs, richens the mixture, retards the spark, and generally makes sure that the car is no fun to drive in that condition. Ford probably makes the worst-case assumption that the oil is end-of-life 20-weight and would have the lowest viscosity that could be in the engine. If the engine actually has thicker oil, there is margin built in with that assumption.
http://www.obd-codes.com/p0026
There's more.
Basically the ecu knows how something should respond when commanded. It then infers oil pressure from that value.
There's more.
Basically the ecu knows how something should respond when commanded. It then infers oil pressure from that value.
Originally Posted By: KrisZ
I'm just curious. How the sophisticated ECU software is to know oil viscosity?
Every time the ECU moves a cam, or both of them, engine power rises or falls a bit. The ECU has tables that compensate for that, adjusting the throttle so that you get smooth, even power delivery even as the cam swings through as much as 30 degrees. Without it you'd get a stumble or a lurch on every cam position change.
That power compensation process relies on knowing where the cams are now (via cam sensors) and where they're going and how long it will take to get them there. The "how long" question is dependent on oil viscosity - the thicker it is the slower they move. There's a table that provides the necessary information for the rate-of-change calculation that is programmed in at the factory based on the specified engine oil viscosity. An engine spec'd as 5w-50 has a different table than an engine spec'd for 5w-20.
Knowing the engine temperature and oil viscosity, every time it changes the cam phaser settings, the ECU estimates the future position of the cam. Then it figures out the corresponding changes in throttle opening to deliver the right amount of air to smooth out power delivery as the cams change position.
All of that said, I've never seen a complaint about poor running as a result of a different viscosity. Personally I never went more than 1 grade away from spec, and when I did I edited the tables appropriately.
I'm just curious. How the sophisticated ECU software is to know oil viscosity?
Every time the ECU moves a cam, or both of them, engine power rises or falls a bit. The ECU has tables that compensate for that, adjusting the throttle so that you get smooth, even power delivery even as the cam swings through as much as 30 degrees. Without it you'd get a stumble or a lurch on every cam position change.
That power compensation process relies on knowing where the cams are now (via cam sensors) and where they're going and how long it will take to get them there. The "how long" question is dependent on oil viscosity - the thicker it is the slower they move. There's a table that provides the necessary information for the rate-of-change calculation that is programmed in at the factory based on the specified engine oil viscosity. An engine spec'd as 5w-50 has a different table than an engine spec'd for 5w-20.
Knowing the engine temperature and oil viscosity, every time it changes the cam phaser settings, the ECU estimates the future position of the cam. Then it figures out the corresponding changes in throttle opening to deliver the right amount of air to smooth out power delivery as the cams change position.
All of that said, I've never seen a complaint about poor running as a result of a different viscosity. Personally I never went more than 1 grade away from spec, and when I did I edited the tables appropriately.
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Gee, and I managed to say most of that with only around 20 words!
And thank goodness for DBW throttles, you should see how the response ramp changes when our 3500 Express fleet trucks go into AFM mode! The tech is fantastic these days...
And thank goodness for DBW throttles, you should see how the response ramp changes when our 3500 Express fleet trucks go into AFM mode! The tech is fantastic these days...
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