TL vs high altitude
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Team Owner
Joined: Mar 2006
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From: Bakersfield
TL vs high altitude
I know this has been gone over before but I haven't found an answer yet. I'm well aware of the effect altitude has on cars, especially NA ones but I'm convinced there's a problem with mine. Lately, in the heat of Vegas and ~2,500' altitude I have to floor the car just to move around in traffic. If there's a situation where I need to ease by someone and I would usually use 1/4 pedal to do it, I now floor it and drop down two gears to do the same thing. Can't even come close to chirping the tires off the start even on slick concrete. I know these cars aren't fast but it's getting dangerously slow. Just getting on the freeway requires I floor it as soon as possible so I'm hopefully going the same speed as traffic when I hit the freeway. I guarantee this thing would not break out of the 16s in the 1/4 right now.
Not only is it slow but it surges pretty bad. Once rpms get to 4,500 or more, power is decent but below that it's anemic.
I'm now visiting family in Bakersfield at ~600' and a couple degrees cooler. As I was getting close I noticed the car was much more responsive to little throttle inputs on the freeway. I was not looking for this but it stood out because there was so much difference. There's an onramp where I have to slow to 20mph before accelerating back on the freeway. As I rounded the corner, I floored it to hopefully get up to speed and had to hold onto the wheel. I was greeted with torque steer and the traction control light flashing. Power was back to where it used to be. Taking off from redlights requires half the gas it did in Vegas. Normal shift points are ~2,500rpm vs 4,500 in Vegas because I'm giving it much less gas for the same acceleration.
Anyone ever find an actual problem with the TL at altitude? There's just too much of a difference for ~2,000' to make. It now feels slower in Vegas than it did when I lived twice as high in Tahoe. No check engine light and all maintenance like air filter has been done. I'm thinking it has to be a sensor or flaw in the engine management.
Not only is it slow but it surges pretty bad. Once rpms get to 4,500 or more, power is decent but below that it's anemic.
I'm now visiting family in Bakersfield at ~600' and a couple degrees cooler. As I was getting close I noticed the car was much more responsive to little throttle inputs on the freeway. I was not looking for this but it stood out because there was so much difference. There's an onramp where I have to slow to 20mph before accelerating back on the freeway. As I rounded the corner, I floored it to hopefully get up to speed and had to hold onto the wheel. I was greeted with torque steer and the traction control light flashing. Power was back to where it used to be. Taking off from redlights requires half the gas it did in Vegas. Normal shift points are ~2,500rpm vs 4,500 in Vegas because I'm giving it much less gas for the same acceleration.
Anyone ever find an actual problem with the TL at altitude? There's just too much of a difference for ~2,000' to make. It now feels slower in Vegas than it did when I lived twice as high in Tahoe. No check engine light and all maintenance like air filter has been done. I'm thinking it has to be a sensor or flaw in the engine management.
Instructor
Joined: Jun 2007
Posts: 183
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From: Bay Area, CA
All I can say is, I've driven at least three times from San Francisco Bay Area (sea level) through Tahoe, Death Valley, and on to Vegas and back, with at least one other occupant, and never noticed even a hint of difference in performance in my old Acura Legend (which was V6 also). So while there is definitely a theoretical impact of altitude, I can't imagine it would be noticeable in 'daily driving'. Vegas is at roughly 2,000 feet above sea-level, while Tahoe is at over 6,000 feet above sea-level. You say it was ok in Tahoe; was that some time back? Have you had any occasion to drive recently to a higher altitude place other than Vegas?
In fact, just two weeks ago I drove to Santa Cruz over highway 17, and I think that road passes through at least 2,000 feet at it's highest point. There was no noticeable performance change on that run.
I wonder if the heat is a factor, combined with some faulty sensor. But then, Bakersfield is not exactly cool, is it ...
In fact, just two weeks ago I drove to Santa Cruz over highway 17, and I think that road passes through at least 2,000 feet at it's highest point. There was no noticeable performance change on that run.
I wonder if the heat is a factor, combined with some faulty sensor. But then, Bakersfield is not exactly cool, is it ...
Pro
Joined: Jun 2006
Posts: 505
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From: Tucson, AZ
I live in Tucson about 2,000 feet. I've driven the car everywhere from sea level (san diego) to 9,000 feet (cloudcroft, nm), including vegas, and I've never noticed any difference in the power level of my '06 5at
Team Owner
Joined: Sep 2006
Posts: 33,535
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Get the codes checked at parts store
I would do a plug check and see if the O2 sensor appears to be working right
Hows the gas mileage?
How many miles- ready for spark plugs?
What about a Seafoam treatment to clean crud from internals and injectors?
I can run from 100 degrees at sea level thru 7000 at hi outside temps and pull srtong all the way
The fuel injection and computer fix the power constantly
2k feet is nothing to the system
I would do a plug check and see if the O2 sensor appears to be working right
Hows the gas mileage?
How many miles- ready for spark plugs?
What about a Seafoam treatment to clean crud from internals and injectors?
I can run from 100 degrees at sea level thru 7000 at hi outside temps and pull srtong all the way
The fuel injection and computer fix the power constantly
2k feet is nothing to the system
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Joined: Feb 2006
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From: Space Coast, FL
there are a few threads on this subject, but they might be quite old. From the experience that i have seen on this fourm the tl's has had a little problem with higher altitude's. This may be due to the high compression ratio of the motor. But as for the power swurge after 4.5k, thats when vtec engages and you get the extra power. also forgot to add, higher temps mean thinner air, which means less fuel which means less power.
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Team Owner
Joined: Mar 2006
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From: Bakersfield
Originally Posted by csmeance
there are a few threads on this subject, but they might be quite old. From the experience that i have seen on this fourm the tl's has had a little problem with higher altitude's. This may be due to the high compression ratio of the motor. But as for the power swurge after 4.5k, thats when vtec engages and you get the extra power. also forgot to add, higher temps mean thinner air, which means less fuel which means less power.
When we hit vtec, what happens to the fuel? Does it get slightly richer?
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Joined: Feb 2006
Posts: 21,406
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From: Space Coast, FL
Originally Posted by I hate cars
The car feels like it's detonating at higher altitudes. I can't hear anything but the surging feels like the computer pulling timing. The fact that it clears up when it hits vtec (it feels like it picks up 100hp) makes me think detonation even more. To give you an idea of the power at altitude, I was in a parking garage with slick concrete and went to take off from a stop making a very sharp turn and floored it without even a screech from the tires.
When we hit vtec, what happens to the fuel? Does it get slightly richer?
When we hit vtec, what happens to the fuel? Does it get slightly richer?
AUTOSPORTZ.COM
(Variable Valve Timing and Lift Electronic Control) A system used in some Honda engines to allow the engine to breathe differently at different RPMs for optimum performance.
INSIGHTCENTERAL
Variable-Timing & lift, Electronically Controlled: This is Honda's term for their technology that adjusts the amount that intake/exhaust valves are opened based on the current engine speed. The Insight uses a variation of the VTEC system that Honda calls VTEC-E ("E" standing for efficiency), that operates only on the intake valves.
WIKIPEDIA
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by the car manufacturer Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range.
My thoughts are that since there is really low pressure, there is much less air in the cylinders, less air means the car redards the timing to prevent damage to the motor, so much less power, though when vtec activates, it allows much more air in and you feel more power.
if you want an example of this, when you put a freer flowing filter/cai the car makes more power due to more air (which is also somewhat cooler), but mostly due to freer flowing air. But put a more restrictive intake on, less power. one way to see if it is air related is to go back up to the mountains and smell the exhaust on the car when it is idiling, if it smells a little richer or leave crud on your exhaust tips you have a air problem most likely, but if it seems normal, i have no idea.
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Thread Starter
Team Owner
Joined: Mar 2006
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From: Bakersfield
Originally Posted by csmeance
this is what i got off the web:
AUTOSPORTZ.COM
(Variable Valve Timing and Lift Electronic Control) A system used in some Honda engines to allow the engine to breathe differently at different RPMs for optimum performance.
INSIGHTCENTERAL
Variable-Timing & lift, Electronically Controlled: This is Honda's term for their technology that adjusts the amount that intake/exhaust valves are opened based on the current engine speed. The Insight uses a variation of the VTEC system that Honda calls VTEC-E ("E" standing for efficiency), that operates only on the intake valves.
WIKIPEDIA
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by the car manufacturer Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range.
My thoughts are that since there is really low pressure, there is much less air in the cylinders, less air means the car redards the timing to prevent damage to the motor, so much less power, though when vtec activates, it allows much more air in and you feel more power.
AUTOSPORTZ.COM
(Variable Valve Timing and Lift Electronic Control) A system used in some Honda engines to allow the engine to breathe differently at different RPMs for optimum performance.
INSIGHTCENTERAL
Variable-Timing & lift, Electronically Controlled: This is Honda's term for their technology that adjusts the amount that intake/exhaust valves are opened based on the current engine speed. The Insight uses a variation of the VTEC system that Honda calls VTEC-E ("E" standing for efficiency), that operates only on the intake valves.
WIKIPEDIA
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by the car manufacturer Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range.
My thoughts are that since there is really low pressure, there is much less air in the cylinders, less air means the car redards the timing to prevent damage to the motor, so much less power, though when vtec activates, it allows much more air in and you feel more power.
Senior Moderator
Joined: Feb 2006
Posts: 21,406
Likes: 2,185
From: Space Coast, FL
don't know what closed loop means but heres some more info that might help a little more. you might understand this due to all the work with the GN, but i don't...
Since I am asked so often how the variable valve timing and lift control (VTEC) system operates, and how to diagnose a code or problem with this system, I decided it's time to write about it.
Honda introduced the first VTEC system on the Acura NSX in the early 1990s and installed it in the Civic 1.6 liter in 1992. There are several versions of the VTEC system, so I will explain how the standard VTEC system operates.
In the standard VTEC system, the engine design uses VTEC technology to vary the lift and duration of the intake valves to provide optimum performance at low and high rpm. In a standard engine, most manufacturers use a camshaft profile that makes a compromise between the ideal valve lift and duration for best low rpm performance and peak performance at high rpm.
When the camshaft profile is too radical, it allows compression to be lost at low rpm when the air speed is insufficient to take advantage of the high lift camshaft. That is why a racing engine will run poorly at low rpm and is not practical for everyday driving. Also, an engine with a mild camshaft profile does not allow sufficient time to fill the cylinder with fuel and air at a high rpm, which can cause the engine to have poor top-end performance. With a VTEC system, the engine will have both types of camshaft profiles.
The VTEC system uses a lower lift camshaft for normal engine operation. When it gets between 4,000-6,000 rpm (depending on year and model), it electronically turns on the VTEC system and the high-lift camshaft lobes are used, creating better top-end performance. This system allows optimum power in both low and high rpm.
The basic VTEC engine uses a camshaft with three intake lobes for each cylinder. The outer two camshaft lobes are for low rpm operation - they operate the intake valves directly by rocker arms. The center high-lift camshaft lobe and its rocker arm are idling and the movement is controlled by a spring, or what Honda calls a "lost motion" assembly.
When driving the vehicle with the rpm high enough for VTEC operation, the engine control module (ECM) operates the variable valve timing solenoid to open the solenoid and allow oil pressure to be applied to the pistons in the intake rocker arms. This action causes the outer rocker arms to be pinned to the middle rocker arm and now the three rocker arms operate as a unit, using the high-lift camshaft lobe for improved high-end power. When the engine rpm drops below VTEC operation, the VTEC solenoid is not energized and hydraulic oil pressure is turned off. This allows the return spring to return the pistons to their rest position and lets the rocker arms operate independently again. The VTEC transition between low and high rpm is smooth and normally not felt by the driver.
The ECM also looks at other inputs for VTEC operation - engine temp, engine oil pressure and vehicle speed (VTEC does not turn on unless the vehicle is moving). A separate oil pressure switch monitors the VTEC system. If a problem occurs, the ECM can turn off VTEC operation and will set a code, turning on the "check engine" light. In some cases, it can also cause a driveability problem.
The VTEC oil pressure switch is a normally closed switch. The ECM sends a voltage to the switch and expects the voltage to go through the switch to ground. If the ECM reads a voltage on that circuit when the VTEC system should not be operating, it will turn on the "check engine" light and set a code. This code will be a P1259 on a vehicle with OBD-II.
When the ECM energizes the VTEC solenoid valve to turn on the VTEC system, the ECM expects the VTEC oil pressure switch to open and see the voltage on the circuit. If there is a delay with oil pressure opening the switch, the ECM will set a trouble code and may limit fuel delivery, causing a driveability problem.
Reasons for no VTEC operation include low engine oil level, VTEC solenoid not opening or the screen behind it is restricted, an engine that has low oil pressure, or an oil pressure leak to the rocker arm assembly. In some cases, when engine work is performed, a missing or damaged O-ring can cause incorrect oil pressure to the VTEC system.
When diagnosing a trouble code P1259, always look at freeze-frame data. This data will tell you if the code is set at high or low engine rpm. If the code is set below 4,000 to 6,000 rpm (depending on the engine), check the oil pressure switch circuit for a faulty switch/connection or poor ground. When the code sets during VTEC operation, check for an oil pressure or mechanical problem with the VTEC system.
Honda introduced the first VTEC system on the Acura NSX in the early 1990s and installed it in the Civic 1.6 liter in 1992. There are several versions of the VTEC system, so I will explain how the standard VTEC system operates.
In the standard VTEC system, the engine design uses VTEC technology to vary the lift and duration of the intake valves to provide optimum performance at low and high rpm. In a standard engine, most manufacturers use a camshaft profile that makes a compromise between the ideal valve lift and duration for best low rpm performance and peak performance at high rpm.
When the camshaft profile is too radical, it allows compression to be lost at low rpm when the air speed is insufficient to take advantage of the high lift camshaft. That is why a racing engine will run poorly at low rpm and is not practical for everyday driving. Also, an engine with a mild camshaft profile does not allow sufficient time to fill the cylinder with fuel and air at a high rpm, which can cause the engine to have poor top-end performance. With a VTEC system, the engine will have both types of camshaft profiles.
The VTEC system uses a lower lift camshaft for normal engine operation. When it gets between 4,000-6,000 rpm (depending on year and model), it electronically turns on the VTEC system and the high-lift camshaft lobes are used, creating better top-end performance. This system allows optimum power in both low and high rpm.
The basic VTEC engine uses a camshaft with three intake lobes for each cylinder. The outer two camshaft lobes are for low rpm operation - they operate the intake valves directly by rocker arms. The center high-lift camshaft lobe and its rocker arm are idling and the movement is controlled by a spring, or what Honda calls a "lost motion" assembly.
When driving the vehicle with the rpm high enough for VTEC operation, the engine control module (ECM) operates the variable valve timing solenoid to open the solenoid and allow oil pressure to be applied to the pistons in the intake rocker arms. This action causes the outer rocker arms to be pinned to the middle rocker arm and now the three rocker arms operate as a unit, using the high-lift camshaft lobe for improved high-end power. When the engine rpm drops below VTEC operation, the VTEC solenoid is not energized and hydraulic oil pressure is turned off. This allows the return spring to return the pistons to their rest position and lets the rocker arms operate independently again. The VTEC transition between low and high rpm is smooth and normally not felt by the driver.
The ECM also looks at other inputs for VTEC operation - engine temp, engine oil pressure and vehicle speed (VTEC does not turn on unless the vehicle is moving). A separate oil pressure switch monitors the VTEC system. If a problem occurs, the ECM can turn off VTEC operation and will set a code, turning on the "check engine" light. In some cases, it can also cause a driveability problem.
The VTEC oil pressure switch is a normally closed switch. The ECM sends a voltage to the switch and expects the voltage to go through the switch to ground. If the ECM reads a voltage on that circuit when the VTEC system should not be operating, it will turn on the "check engine" light and set a code. This code will be a P1259 on a vehicle with OBD-II.
When the ECM energizes the VTEC solenoid valve to turn on the VTEC system, the ECM expects the VTEC oil pressure switch to open and see the voltage on the circuit. If there is a delay with oil pressure opening the switch, the ECM will set a trouble code and may limit fuel delivery, causing a driveability problem.
Reasons for no VTEC operation include low engine oil level, VTEC solenoid not opening or the screen behind it is restricted, an engine that has low oil pressure, or an oil pressure leak to the rocker arm assembly. In some cases, when engine work is performed, a missing or damaged O-ring can cause incorrect oil pressure to the VTEC system.
When diagnosing a trouble code P1259, always look at freeze-frame data. This data will tell you if the code is set at high or low engine rpm. If the code is set below 4,000 to 6,000 rpm (depending on the engine), check the oil pressure switch circuit for a faulty switch/connection or poor ground. When the code sets during VTEC operation, check for an oil pressure or mechanical problem with the VTEC system.
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