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04-06-09, 10:27 PM
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04-22-09, 06:01 AM
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After reading about the supposed benefits of replacing the coolant temp sensor, I did it w/ lexus part to my '92 w/ 170k. over the past 3 yrs. mileage had dropped from about 19.5 to 18.5 despite new o2, wires, plugs, etc... it's only been 2 weeks, but my first tank in same driving to/from work was 20.6. i really didn't notice any improvement in anything else. i am cautiously optimistic, as i've found b/c of many variables, tank to tank mileage can vary 2 mpg or even more, but wow, if this holds....will keep posted.
04-23-09, 07:57 AM
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hmmm.... i don't know why it would. drive by wire is just a linkage b/tw pedal and throttle. i know the ecu can cut fuel/retard spark independent of pedal position, but so can the first gen. witness the trac control.
in both types of cars, the engine ecu is constantly adjusting fuel/air according to a bunch of sensors, so if the cool. temp is bad, it would throw both types off, right?
i understand the drive by wire being more complex, etc... but in the end it's the ecu controlled fuel/air, being guided by the sensors
in both types of cars, the engine ecu is constantly adjusting fuel/air according to a bunch of sensors, so if the cool. temp is bad, it would throw both types off, right?
i understand the drive by wire being more complex, etc... but in the end it's the ecu controlled fuel/air, being guided by the sensors
04-23-09, 09:17 PM
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It is a different beast completly when drive by wire is involved.
So many more variables are used in the dbw system for acceleration over cable connections.
Drive by wire is not a linear input output as a direct cable connection is.
10% pressing the pedal does not translate to 10% open throttle which is why they have aftermarket modules built to give you direct control of the throttle for about $500 .
So many more variables are used in the dbw system for acceleration over cable connections.
Drive by wire is not a linear input output as a direct cable connection is.
10% pressing the pedal does not translate to 10% open throttle which is why they have aftermarket modules built to give you direct control of the throttle for about $500 .
Last edited by skperformance; 04-23-09 at 09:25 PM.
04-24-09, 08:49 AM
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continuing on this purely 'for the fun of it' convo...
yes, i realize the dbw is not linear and the computer can override the throttle, etc... but that doesn't address the point of correct fuel/air mixture to the engine, which was my point in saying that ultimately, after all the spark manipulation, dbw throttling, trac control braking, and whatever else, the engine ecu has to maintain the correct fuel/air ratio, getting data from sensors. in the end, in the combustion chamber, both engines need the correct stoichometric ratio to run most efficiently.
it's because of this, not any drive by wire throttling, that a bad sensor could throw things off.
yes, i realize the dbw is not linear and the computer can override the throttle, etc... but that doesn't address the point of correct fuel/air mixture to the engine, which was my point in saying that ultimately, after all the spark manipulation, dbw throttling, trac control braking, and whatever else, the engine ecu has to maintain the correct fuel/air ratio, getting data from sensors. in the end, in the combustion chamber, both engines need the correct stoichometric ratio to run most efficiently.
it's because of this, not any drive by wire throttling, that a bad sensor could throw things off.
04-26-09, 09:28 PM
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One thing is for sure , jcole you have never driven a drive by wire car or never noticed the lack of direct response from the throttle.
Truly i am not exactly sure why the mapping is so off when temps are different. It is a very precise set of values it uses from the maf , ect and tps to regulate the engine and expecially its transmission gear selection.
Now when you start to drive it should be very linear in output but in a drive by wire car it holds back the throttle power and retards the timing (you can hear it similar to when VSC kicks in ,i also have an exhaust to hear it ) . When things work well the car hauls down the road when the values are off the car is a pig and the tranny is in the wrong gear and going no where fast no matter how much throtle you give it. You cruise for a second and slow down then hit the gas and it thinks for 2 seconds before giving it throttle and or upshifting.
Now when it is working perfectly there is no lag just instant power , it holds the lower gear and will not try to down shift unless you give over 1/2 throttle.
The closest issues i can see is tps values off ,engine temps off, knock sensors , bad o2's , bad ecu's.
So many possibilties to fixing it but it really feels like using 87 octane which funny enough amplifys the issue.
Hope this give you some insight as it is not a straight answer.
Truly i am not exactly sure why the mapping is so off when temps are different. It is a very precise set of values it uses from the maf , ect and tps to regulate the engine and expecially its transmission gear selection.
Now when you start to drive it should be very linear in output but in a drive by wire car it holds back the throttle power and retards the timing (you can hear it similar to when VSC kicks in ,i also have an exhaust to hear it ) . When things work well the car hauls down the road when the values are off the car is a pig and the tranny is in the wrong gear and going no where fast no matter how much throtle you give it. You cruise for a second and slow down then hit the gas and it thinks for 2 seconds before giving it throttle and or upshifting.
Now when it is working perfectly there is no lag just instant power , it holds the lower gear and will not try to down shift unless you give over 1/2 throttle.
The closest issues i can see is tps values off ,engine temps off, knock sensors , bad o2's , bad ecu's.
So many possibilties to fixing it but it really feels like using 87 octane which funny enough amplifys the issue.
Hope this give you some insight as it is not a straight answer.
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