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View Full Version : FX35 AWD, is there a shortage of torque or HP??



Blckthree
03-13-2003, 03:54 PM
I have noticed that my FX35 seems to be either short on HP / torque. With the cruise set and driving along at 75mph, every hill or slight incline on the road, it seems to drop down a gear out of overdrive. It seems to do this especially if you are going into or out of a corner with a hill in it. Is this the same experience everyone else has had? I would think 280 hp and 280 ft lb torque would be enough to pull this vehicle through a hill at 2700-2800 rpm without downshifting! Or is this a product of the rev happy 24 valve V6?

hud2333
03-13-2003, 07:36 PM
Wow. I am very surprised by that one. I have not ran into any huge hills or anything but I have never had any situations where the engine had to down shift. Granted I have only been on a few trips on the freeway. That is were I feel the vehicle is at its strongest between 60 - 90 on the freeway. Sorry I do not have any help.

Ak1nza
03-13-2003, 07:46 PM
I don't think there is shortage in hp/torque. I would think it should downshift because 5th gear is the overdrive gear and is only meant for cruising. I don't find the downshifting a problem.

I do, however, on long trips leave it in the 5th gear in the manumatic mode. I tried this out a couple times and I found mileage to improve quite dramatically. Leaving it in drive and crusing got me around 19mpg. When I put my car in 5th gear on manumatic mode my mpg was able to be sustained at 22mpg. Try it out and tell me if that works.

IgotmyFX
03-13-2003, 08:56 PM
Blckthree,
I guess my question is wether your FX is really downshifting into 4th or is the torque converter going through the 'lockup/unlock' mode changes.
When I am going down the freeway and I encounter a decent hill, sometimes I can see the engine RPMs go up about 500 RPM. This has happened in both Cruise and with my foot on the throttle. It also happens when I give it more gas to slowly pass another car or sometimes increase my speed. Usually around the 75-80 mph.
I would think that the 4th-OD transition is more than 500 RPM. Maybe I am wrong but, I will have to try the manual mode between 4th and OD and see what the RPM diff is.

Ak1nza
03-13-2003, 09:12 PM
I believe what you are mentioning is the downshift from overdrive 5th to 4th. 5th is a really long gear, not very good for pulling the car, i think that's why the auto tranny will opt to downshift to 4th.

Blckthree
03-14-2003, 10:09 AM
I paid a little more attention to the tach today at one spot where I have noticed everyday the same situation. It did jump about 500 rpm, probably out of overdrive into fourth. The other thing I noticed is that it is in a sweeping S curve, coming up out of the second turn where it downshifts. I wonder if it could be the VDC transferring some of the power to the front wheels upon entrance to the turn and the fact that it is doing that, it downshifts. I didnít that it did this on other stretches of the highway where there was a similar hill, but no curve.

Hey, who really cares, this car is GREAT!!!!

IgotmyFX
03-14-2003, 12:23 PM
Blckthree,
I paid more attention last night on the way home too. You are right, it is OD to 4th that is the 500 RPM difference. My bad. I am still learning the car too and I though we had a lock-up converter that saves mileage. Oh well.
Like you said though, who cares, it is a GREAT car. Even though my daily commute is boring as HE**, the FX is still a BLAST to drive.

Blckthree
03-14-2003, 12:55 PM
My daily commute is an interesting drive. I used to complain that they couldn't build a straight highway in Oklahoma, but now I enjoy the curves. I am not sure if we have a lock up torque convertor or not. I have looked and sometimes it appears as though it drops about 100-150 rpm when the cruise settles in, but I am not sure about that one.

Q45tech
03-16-2003, 05:40 PM
HP is just a mathematical manipulation of measured torque [to make the number look higher above 5252 rpm]! AT 5252 rpm both numbers are equal.........at 2300 rpm 2300/5252=0.4379........WOT HP is only 44% of WOT torque

4 valve per cylinder engines have too much air flow capacity at low rpms therefore they may seem sluggish at low rpms [cruise] vs old fashioned 2 valve per cylinder engines which can run out of breath at high rpms.

To make 4 valve engines seem as frisky as 2 valve they generally rev them 10-15% higher at cruise 2200-2300 vs 1800-1900-2000 rpm..........so a smaller modern 3.5 might a get worst [highway] mileage than a old fashioned 3.8 V6 [GM] push rod engine.........all depends on exact gearing.

At cruise rpm all engine are operating at low VE [high vacuum] so they are operating at only 16-20% efficiency vs WOT at the torque peak rpm. Based on air flow a 3.5 maybe acting like a 600-700cc engine at cruise.