Auto trans shifting up/down way too much

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tonyota

tonyota

10 Year 15 Year
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Jan 13, 2007
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In the garage.
Looking for help

88 4runner, 3.4 swap, stock 88 automatic transmission, 4:10 gears, & 33" tires.

trans works fine @ actual speeds under 45 MPH. ( speedo reads slower)
At speeds over 45 actual MPH the trans shifts up & down constantly, I do mean constantly, until I reach actual speeds of 63 MPH or higher
then it stays in O.D. & locks up t-converter like it should.

I have adjusted the T.V. cable to factory spec, played with the adjustment to where it is too tight, tried it too loose & everywhere in between & still have the same problem.

Replaced the T.P.S. upon recommendation from a friend, no change.

Suggestions anyone? Sure fix, anyone?
 
tonyota said:
Looking for help

88 4runner, 3.4 swap, stock 88 automatic transmission, 4:10 gears, & 33" tires.
Click to expand...

It HAD 4:10's with the 28's...

Now, of all intents and purposes, it's got 3:60 gears...

There are no gear and wheel speed sensors... The tranny could care less what gears and tires you really have. That tranny works off of set RPM's (That MATCH to the engines torque output at x speed:RPM) at such load and whatever.


tonyota said:
trans works fine @ actual speeds under 45 MPH. ( speedo reads slower)
Click to expand...
See above.



tonyota said:
At speeds over 45 actual MPH the trans shifts up & down constantly, I do mean constantly, until I reach actual speeds of 63 MPH or higher
then it stays in O.D. & locks up t-converter like it should.
Click to expand...

See above. With the added weight and increased friction of your new tires, plus load, your truck thinks it's permanently tied to a 25 foot Carolina Skiff...


tonyota said:
I have adjusted the T.V. cable to factory spec, played with the adjustment to where it is too tight, tried it too loose & everywhere in between & still have the same problem.

Replaced the T.P.S. upon recommendation from a friend, no change.

Suggestions anyone? Sure fix, anyone?
Click to expand...


Yeah, gears. Look for a gear code I don't know by heart, but IS in the FAQ.
4:88's and 4:56's came factory in some AT trucks and 4Runners.

Then throw that POS A340H away and get an f case off a 22R/E. Swap linky

"Why are vehicles with the Toyota A340H trans/t-case so gutless?
(Compared to their 5 speed counterparts with the same motor). Normally, an auto tranny both consumes power and mutiplies torque. In the case of the A340H, the power consumption is doubled by the addition of the hydraulic transfer case, which is essentially like having another automatic transmission inline. But the torque multiplication of the single torque converter isn't enough to compensate for the additional drag. A simple though exspensive solution is to replace the hydraulic chain driven transfer case with a gear driven one. Inchworm and Gearslug are some of the only vendors that make an adapter for this application. People who have performed this mod report increased mileage and performance, most likely due to the elimination of the additional drag of the hydraulic t-case. Note that the chain drive case has a 2.66 to 1 low range so going to a single stock gear drive case will lose some gear reduction."




PS, I accept Pay-Pall, Peanuts and Prostitutes.
 
Last edited:
You can also try turning the ECT button OFF.

That changes the up/down shift points 500rpm higher.
And it's easier to go from OD to D.


And what the heck is a T.V cable? (Never mind. I can figure it out.)
 
Thanks for the input.

yeah, I know another tranny/t-case will do the trick, but that's not in the budget just yet.

I would like to change the gears anyway, so that just might be my first step.
I figured the gears as part of the problem, what with the taller tires & all.
Just kinda hoping someone would say" I had this happen & here's how I fixed it with no cash & in 5 minutes"
 
Mechanical speedometer cable? With the 3.4 swap did the wiring to the dash get disturbed? In 88 I'm pretty sure the "vehicle speed sensor" was in the back of the gauge cluster... if the wiring was messed with back there the Trans may have lost it's speed input signal....
 
Tranny was controlled by separate control box with 3.0
But is controlled by the ECU with the 3.4
 
Yes, when on 31" tires it acted just like it should.

Went in & found no engine to body ground, fixed that.
No trans to body ground, fixed that
Gave the T.V. cable another adjustment (to the side of looser)
Prayed over it really hard!
And it worked just fine today at all speed & all conditions, hmmmmm.
Was up in the mid 40s today temperature wise.
I don't know if that should matter

I firmly believe it's fixed !!

I will keep ya posted on the success of this issue
 
my wifes truck (02 3.4l Supercharge 4x4 double cab) was having similar problems, and it ended up being a couple of problems.
1)the transmission was going bad, need some work.
2) the other problem that made the transmission start to hunt for the right gear, was a couple of coil packs where bad, still worked, did not throw a code, but a miss would show up under hard acceleration.
 
Thanks for the input
Mine works fine still although it seems to do its best when the weather is warmer
That seems a bit strange to me
But now only occasionally hunts for a gear when below freezing
Flawless operation when above freezing
 
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