Power Loss

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borabora1

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I just bought an 2003 FX 35. I am very pleased with the luxury and a lot of features. My only complanit is the lack of power. The most strange thing is that it has 280 horsepower that doesn't feel like. There are no check engines. I just change the filter to a K&N. It improves a little bit but not that much? The mileage is 97K.


A need your advice where to start? Sparks plugs, catalyst, oxygen sensor?

Thanks in advance
 
borabora1 said:
My only complanit is the lack of power. The most strange thing is that it has 280 horsepower that doesn't feel like.

Thanks in advance
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Out of curiosity, what's your point of reference? When I drive my Z (400 whp) or have a G37 loaner car for a few days, going back to my FX makes it feel slow...
 
try an ecu reset. Possible that it's in conserve mode from prior owner.
FX is heavy. Never gonna feel like the others straight out of the box, but it isnt slow
 
borabora1 said:
I just bought an 2003 FX 35. I am very pleased with the luxury and a lot of features. My only complanit is the lack of power. The most strange thing is that it has 280 horsepower that doesn't feel like. There are no check engines. I just change the filter to a K&N. It improves a little bit but not that much? The mileage is 97K.


A need your advice where to start? Sparks plugs, catalyst, oxygen sensor?

Thanks in advance
Click to expand...

just curious, what car did you drive before prior to buying the FX?

and also, there's a difference between manufacture's stated "HP" and "actual HP AT the Wheel".

these two questions are rather important because suppose you came from a car (NOT SUV/CUV) that had say... 220-250 HP... this FX might not feel as fast is because you need to weigh in the fact that it's a heavier vehicle... probably heavier than whatever you were driving before.
 
You really can't compare a normal cars HP to that of the FX due to the added weight. The FX will always feel slower than a regular sedan or 2 seater sports car.
 
I already have a 2005 corvette, maybe my reference is the issue. But seriously the accelaration doesn't seem so fast for 280 hp. Maybe I am comparing to 280 in a car. However I will star with spark plugs and the valve covers.
 
trainerKEN said:
you DO know that the FX is like 1,000lbs heavier than an average car, right?

your RWD FX is 4204lbs @280hp
the 05 Vette was 3179lbs @400hp
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Maybe I am still not used to a SUV. I just thought those 280 will pull my back to the seat when I hit the gas . I understant the 1,000 lbs haevier and 120 hp less. Just curious about a possible problem in mechanics:confused.:.
 
borabora1 said:
Maybe I am still not used to a SUV. I just thought those 280 will pull my back to the seat when I hit the gas . I understant the 1,000 lbs haevier and 120 hp less. Just curious about a possible problem in mechanics:confused.:.
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well, it wouldn't hurt to have your FX looked at... but keep in mind it's a combination of both heavier vehicle AND less hp... AND the fact that it's a higher profile car.

Or think of it this way... a 1000lbs is like having 4 heavy set people riding in your car (NOT including the driver).

I think it's just getting used to driving a different kind of vehicle...

I bet your FX would do a better job towing a trailer up a dirt road tho (even if it's not a AWD). :wink (2):
 
Let's also address Infiniti's claim of 280hp. I doubt it's at the wheels - most likely at the crank. Standard 15% loss for an auto RWD drivetrain gets you to 238hp to the wheels, which is STILL optimistic based on those who have put their 1st gen FX up on a dynomometer.

I had my 2004 modified with all the NA bolt-ons I could get my hands on. The first dyno put down 211whp on a Mustang dyno. Since that was AFTER all my bolt-ons were installed, you could expect the FX to come off the factory floor right at 200whp to the wheels.

After I had my ECU tuned, I was able to hit 236whp. I really think it is not realistic to hope for much more than that, even with modifications.
 
I experienced a significant power loss with my 2005 FX35. The vehicle felt sluggish, like I was towing something, like the vehicle was "puking" into every up and downshift, like it suffered from bad turbo-lag (even though it doesn't have a turbo!). I tried everything to fix the problem, air filter, plugs, etc. I even had Infiniti reflash the CPU. Nothing worked to restore the power loss or poor sense of driveability.

A few weeks ago I developed a bad squeal from the serpentine belt. Upon examination, the belt was fine. The bearings on the two idler tensioners however were practically frozen. Once the tensioners were replaced? Much to my surprise, I had a brand new vehicle -- one that I otherwise was getting ready to trade! All of the power loss issues were gone....the vehicle has run terrific ever since.

I've since told Infiniti about this coincidental finding. They agreed if the serpentine belt was dragging in any way, that could certainly cause misinformation to the various system sensors....lead to all the problems I'd been experiencing....and not necessarily bring up a "Check Engine" indicator or bring up any failure codes on their diagnostic computers. Inasmuch as they were grateful for this insight, I'm hoping they'll put out a TSB alerting all their dealers and service managers to check for this potential problem....especially when there's no other explanation.

Could this perhaps be the underlying reason for any others experience a performance and/or driveability issue?
 
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