CaptMarty

Is anyone experiencing a low speed transmission surge or hesitation when appling first applying the gas at parking lot speeds.? I especially notice it when traveling downhill or a slight decline. The motor revs as if in neutral then the transmission catchs on. I mentioned it to the dealer at the 1000 mile check up and they said they could not find anything wrong. I'm getting ready to take it in for the 5000 mile service. Any help woould be greatly appreciated. Not a very smooth transmission considering the price.

Thanks

Tampa FL

Craig B

No, I haven't had that problem with mine. Are you running premium fuel? I run 93 octane
BP, or Phillips/Conoco 94 octane premium...

SaniDel

Sounds familiar ... the slower the speed and the softer you press the gas pedal, the more clumsy the vehicle becomes. Just when you need smooth and gradual, it becomes rough and jerky! Makes it hard to glide through the parking lot without attracting attention, eh?

I'm convinced it is a result of the transmission attempting to upshift at the earliest possible point, which often means it is in too high a gear for the conditions. The hesitation occurs when you need to accelerate, but the transmission has to downshift first. After that happens and the vehicle surges forward, the transmission upshifts and the cycle repeats ... hesitate, downshift, surge, upshift ... repeat forever!

Pull the shift lever to the left, which will put the transmission in the 'S' mode with the upshifts limited to 4th gear. If your speed drops low enough, such as maneuvering in a parking lot while searching for a parking space, pull back to limit to 3rd or again to limit to 2nd gear ... 1st gear is too jerky for anything other than hill climbing or steep descents.

Once you get back on the road, push the shift lever to the right and let it shift for itself. Even better ... leave it in 'S' and push forward to '6'. You may notice the shift points advance slightly, i.e., the engine revs further before it shifts. Even better, pulling back on the shift lever in 'S' keeps the shifts sequential, e.g., 6, 5, 4, 3 etc. rather than an non-sequential 6 to 4 "double-downshift" when you go 'left' from 'D' to 'S'.

You will pay a small price in mileage for using the 'S' mode, but good gas mileage isn't why we bought the GX 460, right?
Regards,

SaniDel


P.S. As Craig said, this problem could also be caused by low-octane fuel, but I use only 93 octane in sea-level Delaware as you in Florida. The problem is the transmission ... low-octane fuel could make it worse, but using the transmission as suggested solves the problem ... with the proper fuel.

CaptMarty

I'll give it a shot. They just picked it up to perform the 5000 mile service. Are the any performance parts available yet?

zpaul

Same problem!
Had to get into traffic and I was sure that I could push it faster than it stated. Barely caused a collision. WTF?!?
At least I am not crazy.
Should be fixed

gxgrappler

I've seen a similar phenomenon and I think Sanidel is on target. The transmission has been tweaked to push the gas mileage up, and there are side effects. I think this is one of them.

SaniDel

Giving credit where credit is due, GXgrappler first made the suggestion to drive in the 'S' mode. I've been doing it for several months now and am convinced it is best for anything other than sustained highway driving, especially if you must drive smoothly at slower speeds such as in heavy traffic.

Other than having to "stir the shifter" there appears to be no downside to driving in the 'S' mode, even if you leave it in "S 6" ... for all intents and purposes that is the same as 'D'. However, the real benefit is to think of the shift lever as a "shift limiter" ... it keeps the transmission from upshifting any further than the gear number displayed on the dashboard.

The main benefit is improved drivability ... the GX becomes easier to control and especially to avoid surging when maintaining a constant speed is important.
Regards,

SaniDel

genedwes

Hey Craig.. to follow up on a previous thread I started.

When you are driving your GX in cruise on a grade is it possible to be in manual mode on a GX and be in cruise without downshifting? Possibly the GX's top gear is to high to keep the speed on cruise?? Seems like your problem would get very irritating for a user that drives lots of miles per year. Sorry for getting back on the subject but have never driven a GX and was planning on a test drive. Thanks for your help.
Gene

Guess I should have stated that I was referring to an uphill grade!!

Koz

You can use cruise in full auto (D) or using the gear selector to prevent downshifting uphill.

Koz

SaniDel

Really? I've never used cruise control in 'Sport' mode, but what happens if the engine can not develop enough torque to maintain speed on an uphill? Does the GX slow until the road levels?

If so, that may be a more 'reasonable' mode for driving with cruise control on mountainous terrain. The problem I have with cruise control is that it tries to maintain speed "come hell or high water" ... the transmission will downshift repeatedly and race the engine to maintain speed, which seems excessive. More to the point, that's not how a car is driven ... slowing slightly on an uphill is natural, not to mention safer since all uphills eventually end and the road 'disappears' on the other side of the crest of the hill.
Regards,

SaniDel


P.S. For a dramatic example of the hazards of uphill driving, imagine trying to drive this uphill course!

http://www.youtube.com/watch?v=7VAJa...&feature=share

Koz

6th gear is very high (1:0.59) and even with the low (1:3.91) final axle ratio, 5300 lbs is going to cause downshifting until there is enough torque to maintain the set speed on inclines. This is normal with this gearing. This gearing has several advantages like off-road crawling (complimented with low range and crawl control), highway gas mileage and towing. At highway speeds (50 to 65 mph) you can tow (within tow rating) any incline in 4th (approx 2800 to 3K RPMs) without downshifting (and still get decent mileage - 14/15 mpg) USING cruise.

When approaching an incline that has been triggering downshifts tap the selector into sport mode (which defaults to 4th) just before ascending (RPMs will increase). If you select sport before there is a load on the engine the downshift should be smooth (without any jerking). You know that in 6th it will downshift so try 5th first and see if it hold the gear. Depending on weight, engine RPM and incline rate you may need 4th gear (at highway speeds).

Once you have found the right gear (without excessive downshifting) you can then use cruise (on highways).

Koz

SaniDel

Thanks for the useful advice, Koz.

Our only experience driving our GX on hills is the Pennsylvania Turnpike, which is more curvy than hilly. I noticed that using cruise control in 'Drive' would turn off the 'ECO' light first, then downshift to a lower gear to maintain speed. As the road leveled the transmission would upshift and the 'ECO' light would go on again. So, it seems the 'ECO' light is an indication of whether the GX can develop sufficient torque on an upgrade or whether shifting into 'Sport' as you recommended is a better choice.
Regards,

SaniDel

T4Fun

driving the pa turnpike is quite difficult, even in a nissan murano which blows this away in handling and acceleration...that being said, you shouldnt be using cruise control on this road with the mountainous terrain. i imagine in the gx you should not be going faster than 70-80 anyway in those curves

SaniDel

I agree with your comments about the PA Turnpike and let's not forget those tunnels ... all five of them!

However, we had no trouble with our base GX460 with or without cruise control. My wife prefers to drive 'manually' and I prefer to 'cruise' but I set it at the speed limit and use my foot to push it up to where I want to drive. If I need to slow I take my foot off the gas and it drops back to the speed limit.

You're right about the maximum safe speed on the curves, but the GX handles them well even at those speeds.
Regards,

SaniDel

russcarver

I agree! Coming home from KS to CO on the interstate at 80mph was uphill mostly and the downshifting constantly irritated me! I had to drive manually at many times. I miss a CVT...

--Russ