Road Trip With the S/C

I have just returned from a 'dance all night under the full moon' hippy wedding in the desert of southern utah... very, very fun! :jump:
This was also my first chance to do a road trip with the new S/C. I'm usually saddled with a one ton pickup and a huge six horse trailer, and this was one great change. The S/C was wonderful. It's not much in play when rock crawlin on desert trails, but it sure is on the hiways and roads gettin you there!!!

It's greatest significance is in passing on hiways. On two lane hiways, I can now pass 2 or 3 vehicles at once in the same time, where, before, I could only pass one. :freek: The passing speeds are indeed wonderful. I can also zoom up steep mountain hiways, passing everyone else who has been forced to slow down due to the inclines.

The extra speed and power do bring up one new big desire. With the S/C, the VX really cries out for a manual 5 or 6 speed tranny. I so want to control where I am on the tach. Manually shifting the stock auto with this new power, is kinda like kissin your sister.:goof: If given a choice, I would trade the stock TOD for a manual 5 or 6 speed with locking front differential immediately. And for those who think that the VX will not shift to a higher gear on its own, when set in '2' or '3' manual/ auto, you are wrong...( maybe I have the Interceptor set wrong?)

The S/C does seem to increase the VX's thirst. I didn't keep very good records, but it still gets near 300 miles on a tank with a very heavy foot. And heck,... everything is more thirsty in the desert.

Also I should add that I may not be the best choice for a test pilot. I don't live in the city and don't get to drive with hi speed stop and goes very often. I do take very winding, curvy, dirt mountain roads regularly, and, hitting the gas coming out of a sharp hi speed turn, has just gottin a whole lot more fun, real fast!

As I have said before, the S/C is all that I was hoping for,...and more! It truly does gives the VX the teeth that its strong, muscular body (and fanged front end) always said that it had.:bgwp:

Interesting update - hope you are using 91 or better gas.

Transmission SHOULD stay in the gear you put it in (L,2 or 3) until you hit the limiter - all ‘99s that I have driven do that. When it hits the limiter at 6000+rpms, it cuts out the motor intermittently to keep the revs down and save the engine. With or without the Interceptor. What year is yours? Please post the rpms and speeds that it ‘automatically’ shifts at in those three gears.

Mine does the same thing Bam Bam, I have a 2001 and I have to go up a very steep incline daily from a stop, when I put in 2 to keep it from shifting into 3rd it shifts into 3rd anyway and than I loose the power.:o

That's very strange, I manually shift a lot and I have never noticed this with mine. Other than the cut off, It zooms up there and stays....

I think it has to do with the torque converter locking up, and forcing the tranny to shift.
It was discussed a little in this old thread about an early dyno test for a S/C:




http://club.vmag.com/ubb/Forum39/HTML/000168.html


""Bob is right. John Finell of Mike Hamm Engineering told me that they didn't know how to disable the torque converter and wasn't able to prevent the gears from shifting. As I remembered he said they tried to run the
test on 3rd gear but couldn't maintain it. The increase in power caused the torque converter to kick in.
I think that's what John said. Sorry I'm not very good with auto technical jargons.
Maybe someone in this forum could explain this a little better.""


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"FeatherFoot
Visiting Member

Posts: 10
Registered: Nov
2001
posted 11-28-2001 03:43 PM

"There seems to be some question about the drop in HP @ 3800 rpm.

that is where the Tq converter locks up. Unfortunately, we were not able to lock the TC in third gear. We have cables for that with other models, not the Isuzu.....ect"

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I talked with Tone about this last night. It seems to happen only when climbing steep inclines. I'll try to duplicate it today on our local mountain pass.
It happened just 5 times only on the whole trip that had mucho steep hills. Each time it caught me by surprise, and I didn't try to duplicate the event at that time.

It did force me to either stomp on the gas to downshift, or to shift to 'D', then back to '3' real fast, to downshift and force it back to '3' again.
Again,... this happened only when climbing a steep hill at speed. At all other times, the tranny operated perfectly with the S/C. And I truly love this mod!
:rotate:

Do the people that this happens to all have the Interceptor installed?

Nope, my interceptor works fine... The pattern I see is the 2001

VehiX, I very much agree with Scott,.... it has nothin to do with the
Interceptor. I was wrong in suggesting it. Actually, I didn't think it did when I wrote it. My bad...:mbrasd: .
Its easy to forget how our words spoken here, no matter how innocently, can, sometimes, take on a life of their own.
***************
I am surprised that people who have been towing larger loads with the VX, have not seen this gear slippage under very high torque conditions... go figure...Maybe it is just 2001's, but don't any 2001's tow?

I will get out and try and duplicate the gear slip today. (we ended up planting trees yesterday until dark ...no time for 'test piloting'...lol) :rotate:

Quote:

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Originally posted by BaM*BaM
I am surprised that people who have been towing larger loads with the VX, have not seen this gear slippage under very high torque conditions

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I thought this was about unwanted shifting. If you're getting slippage you should get the tranny looked at under warranty ASAP before the clutches, or worse, burn up.

Yikes,....me and my words! Jay, it is about an unwanted gear change from either '2' to '3', or '3' to 'D'.

Just checking. When I'm running the rallycrosses I leave it in L and have never had it shift up on me, even when hitting redline. The Houston series had a lot more speed in it and I left it in 2 without any problems.

But what is confusing the issue is this statement:

BamBam
"It did force me to either stomp on the gas to downshift, or to shift to 'D', then back to '3' real fast, to downshift and force it back to '3' again. "

Lockup IS very different than shifting up and WILL happen AFTER the vehcile makes any shift and will feel like a loss of power or slippage. The Interceptor allows you to delay this lockup until you are farther into the powerband of the gear just shifted into. Of course you are in D, it will be more pronounced but has no bearing on the issue of the vehicle not staying in L,2, or 3 - in 2 or 3 the tranny will downshift below the setting but not above.

To test, put it L and drive until the rev limiter kicks in @ ~6500rpm
Then repeat in 2 and 3
It you hit the rev limiter in these settings, then the tranny is NOT shifting up above it's setting.

Hey Tone , we'll give 'er a try when it stops snowing on our local pass. I have very little doubt about the tranny actually shifting higher tho.
Dragon Bob has had the same experience soon after getting his S/C. This is a quote by him from the above dyno test thread.
Dragon Bob wrote:

""Tone: First I have never been able to keep my VX from shifting from 3rd to 4th while selecting 3rd gear. The power switch keeps in third a little longer but it shifts to 4th no matter what. My 99 trooper also acts this way.
... Lastly, when the Dyno was connected the front shaft was disconnected and thus all the BHP was delivered to the rear wheels. Was the TOD or front shaft disconnected on your Dyno runs?""

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I think it possibly has something to do with the difference between a steep incline road and flat roads. On the steep, uphill incline, the HP's are concentrated almost all on the VX's rear end,... similar to the Dyno test effect of disconnecting the front shaft., " thus all of the BHP was delivered to the rear wheels, " where the 'lock' on '3rd' couldn't be maintained."

'VX crazy' states similar results in her reply above,... that the same thing happens to her daily as she ascends "a very steep incline."

Possibly, when a lot more HP's are concentrated on the rear and not partially distributed to the front via TOD,... the more likely it is for the torque converter to force a shift to the next higher gear??

I also think that this is still a very rare event. It is just too unlikely for all of the required variables of relative speed/ rpm's, road incline angle, hp, torque, and TOD functions to match up enough times for this to become a 'normal' event. Living in the mountains and having an S/C , (as Dragon Bob and I do) should add considerably to its chances to occur.

I don't think it has anything to do with the SC but I will test it on a '99. If they changed the trannies to loose that ability to select and stay in a gear, I'm glad I didn't get a '00. Bummer. I can drive on the highway in 3rd and it will NEVER shift to 4th - same with the other gears.

Now when you're talking TC lockup, mine in higher gears feels like it goes into a completely different gear and it could feel as if 3rd goes to 4th..

My MY01 most certainly bounces off the rev limiter in 1. I've never pushed 2 far enough, mainly because it's over 70mph to do that.

-Daver

I'll test several VXes this weekend ( '00 & '01) but have no doubt they ALL will stay in or below the gear selected - that is how automatic transmissions are designed and WHY they have the selections that they do. Most importantly when towing, you want to be OUT of OD (4th) and remain in 3rd, especially on hills. Torque converter lockup is what I believe the confusion or feeling of a 'shift' up to be while operating in 3rd.

The mountains' aspen are beginning their autumn explosion of color. The bull elk are singing their love songs, and this is a great time to be driving a VX in the high mountains.
Today I got to try and check the mysterious gear changings.

What I have found, is true only for the locked in '3rd' gear position,... and only on STEEP inclines.
The tranny will definitely shift from 'locked' 3rd to '4' (or 'L'). It is easiest to duplicate this event when I have the engine rev'ed to hi RPM's ( over 4000), and then give a very slight let up on the gas. It will instantly shift everytime from '3' to '4'( or 'D'.)

Today, only once could I duplicate it shifting from 3 to 4 as I kept the gas constantly pressed. This was at ~4500- 5000 RPM's. (still a long way from red line).

I could NEVER get it to shift out of '2' when I had it locked in '2'.

I tried only once in locked 'L' or '1', and could not get it to shift out .

I could NEVER get it to shift out of '3' when I was on relatively FLAT roads!!

**

It may be that my tranny is malfunctioning in '3' gear. On the steep roads, '3' acted much the same as normal 'D'. Not quite the same, but somewhat similar in feel and gear change.

Since this gear change occurs ONLY in '3', it makes me wonder if this is what happened to 'Dragon Bob' and 'VX crazy' since they have had this gear change occur also in locked '2' gear.

My problem with this is very, very minor, and I don't think that the S/C has anything to do with the cause. It only accentuates it. And remeber, this occurs for me ONLY on very steep mountain pass type roads.

Happy Autumn Trails, :rotate:

This is only the converter lockup you are feeling NOT a gear change - it will stay in 3rd and NEVER go any higher unless you shift it to D. I've talked to several Isuzu mechanics and engineers and drove 3 different VXes this weekend (SCed '99, '00 and an '01)- it's ain't a shift! But the locking and unlocking of the converter does feel very similar.

What does this mean:
(L)

Quote:

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The tranny will definitely shift from 'locked' 3rd to '4' (or 'L').

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Yes, the tranny will shift all the way down to 1st while in 3rd or 2nd.

Did you perform the rev limt test I suggested?

Try shifting the lever to D after this mysterious shift has occured while you are running at 4.5-5Kand you feel the real shift to 4(D).

I ran in third to almost a hundred (and kept the accelerator floored) up a very steep incline (2222 towards 620) and never had it auto shift to 4th.

I was trying to be helpful and test this in an '01. In 1st and 2nd it would bounce off the rev limiter. In 3rd, I was watching the tach instead of the speedometer, steadily gaining speed, when I glanced over at the speedometer and saw I was going over 90 and decided I wasn't the person to be doing this test. I kept expecting to see George behind me with lights flashing. :)

Glad to see Tone had better follow through than me.

:freek:We like to think that higher points ARE given for greater effort...!!!
LOL!;Db;

Just to add to the body of testing here:

Just last week I was playing with this issue on my 01, and my tranny definately did not shift out of the gear I put it in, and the rev limiter works just fine (it's not fun, but it's fine). Granted, I was on flat city streets.

On another note, Daver is worried about going over 70mph... FWiW, I took a quick jaunt over to Detroit Monday, which is about a 4.5 hour drive. about 220 miles of that are 1-94 in Michigan, which is long, straight, and has a posted speed limit of 70.

Suffice it to say, our VXs can do speeds, um, in excess of 70mph for long periods of time and do quite well. And for those who haven't road tripped in their VXs yet, those Racaros will keep your back and butt feeling fine for quite a while. I never even got "numb butt."