Poor performance

[SIRCO]

My 2000 VX has 42,000 on it and it is bucking
once only at about 20mph and again at about
30mph. I always us 91 or 93 octain. The funny
part is, I moved from Buffalo, NY and always
used Mobile gas. Now I am in Queen Creek, AZ
and am using this gas at a place called the Circle
"K" I am not sure if it's the gas of what. No lights
are coming on and after about 10-15 minutes it
runs perfect. Any ideas? Please help getting very
nervous. Thank you in advance. Oh, do we or should
we flush the transmisson? I have my VX checked
every oil change (3,000 mile and I use Mobile 1).
They always say it's in ship shape...and now this.

[Dare2Dream]

You're better off making a new thread about your specific problem and make the title more informative. But before you do that, it is best to search the forum for past threads.

I don't know what might be causing your problem, i also use circle K and have never had any problems. The manual recommends 87 octane but higher shouldn't hurt.

It is recommended to get the transmission flush with filter change atleast once every 30K. Some recommend changing the fluid every 15K and filter every 30K. I recently got the full BG machine flush and tranny filter change for $160 at a local shop. Just call around to find a good deal.

[Moncha]

Done

[Anita]

Sirco,

Is it bucking when it up and downshifts? If it is happening then, it might be your Mode switch. Search on "mode switch" or check this thread for some info:

http://www.vehicross.info/forums/showthread.php?t=7506&highlight=mode+switch

[mbeach]

I got bad gas (water infiltration) many years ago at a Circle K in El Paso.
I've also had problems with the 'oxygenated' summer gas sold in the southwest.

Could it just be bad gas?

Oh, don't waste your money on the high octane stuff. Just get your gasoline from reputable gas stations and you should be just fine.

[Maugan_VX]

also, "coughing" could be caused by a leaky Intake Manifold Gasket with a cold engine. After a couple of minutes running, the symptoms disappear.

Although I wouldn't call the symptom "bucking" its an easy problem to diagnose (not so easy to fix though)

[SIRCO]

It only does it at start up and when it is upshifting. I am
the furthest thing from a mechanic, but get the jist of
what you are saying. I am going to try 44K Power enhancer
and see if that works. Then the Isuzu Dealership mechanic
recommended new plugs, air & fuel filter. I thought we were
not supposed to change the Transmission fluid for like 100k
miles? Is that wrong? As I get everything serviced at the
dealership and they have yet to do it, and they do everything
else. I really apprieciate all the info as I just moved to AZ and
don't know many people and you know the looks you get with
the VXs. So asking "Joe Auto Shopguy" I always get the same:
"I've never seen that kind of SUV, what is it?" That comment
gets me a little nervous to ask him to look my baby over.
Any other suggestions would be great. I did try to start a new
thread...must not have done it correctly. -SIRCO

[VehiGAZ]

I had an isolated-incident problem a few months ago that sounded similar to what is happening to you. What happened to me was that one day, out of the blue, the 1-2 and 2-3 upshifts felt like they were beign executed with a sledgehammer - just a really hard, abrupt, sharp upshift. The 3-4 upshift was fine - but the first two were really nasty. These shifts occur close to the 20 mph and 30 mph marks you mentioned.

It only happened that one morning on the way to work - when I went out to lunch that day, the problem was gone. But it was definitely a transmission issue. I called my dealer about it, and they suggested that it might be a problem with the actuation of the transmission solenoids. But since it went away, I didn't do anything about it.

I'd suggest taking it to an Isuzu dealer who knows what they're looking at for diagnosis. At the very least, have your tranny fluid flushed - it should be done at each (or every other?) major (30k) service. Two local Isuzu dealers talked me out of the filter replacement, insisting that the tranny flush will back-wash the filter and clean it out. Although that sounds a little too good to be true, when a dealer doesn't want to do a service I am asking for and willing to pay for, I listen to them. If they won't want the money, it must REALLY not be worth doing.

Good luck!!

[thedutchguy]

Probably BUCK :laughy: :laughy: :laughy: shot.

[Maugan_VX]

vehigaz,

my VX does the same thing pretty regularly. I really noticed it when I'm accelerating from a stop light and when going from 2 to 3 but I have let up on the accelerator. In effect I'm coasting from 2nd to 3rd.

Just had the transmission serviced about 5k ago with a filter change at a place that I trust to do good work.