1998 Chevy K1500 tranny kicks down too high

[Mikie Mikie]

I've got a 1998 Chevy K1500 extended cab, extra heavy rear springs and locking diff, pulling my 21ft SeaFox center console on interstate 75 we hit a little hill at 70 MHP and the tranny kicked down into passing gear and tried to blow the motor and melt the cat, how can I get the auto trans to stay in the same gear while I give it more gas? Is there an adjustment or a chip that can do something?

 

[pondwaider]

Re: 1998 Chevy K1500 tranny kicks down too high

have your mechanic see if your ecm has the most recent transmission update for shifting. there was a shifting problem with those trans.

 

[windsors03cobra]

Re: 1998 Chevy K1500 tranny kicks down too high

Blow the motor and melt the cat ? Mm nah its just doing what it does "automatically". Your trying to accelerate or maintain speed on a hill that takes power and or a lower gear when the power is not enough.

Maybe you have a 4.3 pick-up ? Those can be a bit doggy.
I had a tiny 4 banger pick-up, a 2000 S10 Xtreme and it would do this kickdown, rev to the moon and melt the brain while empty and uploaded.
Xtremely dodgy was about it, brother his it now with about 175k and its still melting brains when it revs and screams and cries out. GM

 

[kenmyfam]

Re: 1998 Chevy K1500 tranny kicks down too high

They kick down depending on load, speed and rpm.
Could well be what it needs to do, especially at higher speeds.

 

[Josh P]

Re: 1998 Chevy K1500 tranny kicks down too high

It wont blow the engine, there are 4 tables that have tons of numbers that the powertrain computer looks at to decide to shift. Rpm, throttle angle, current speed, and current gear. it knows what the outcome of a downshift will be as in what rpms and speed it will be.it will not let it redline because the trans has 3 tables it must meet to make an upshift. rpm, throttle angle and speed.Gm has it set up in the rpm table at redline it will force it to upshift. the only thing it dosent know quickly is if a trans component is slipping it can tell but it if thats the case will take it atleast 2 times to slip before it throws a dtc and it will on your vehicle its new enough. what was the rpm when it down shifted? You have a 98 which has the 4l60e which is all electric and pcm controlled. no adjustments maybe a "chip" but sometimes not worth the money

 

[H20Rat]

Re: 1998 Chevy K1500 tranny kicks down too high

lean conditions melt cats... More chance of that lugging it in too low of a gear. High rpm/light load won't do it!

 

[Silvertip]

Re: 1998 Chevy K1500 tranny kicks down too high

There is no passing gear - period. What you are feeling first is the torque converter clutch releasing. If you happen to be in overdrive, the next downshift will be out of overdrive and into direct (1:1). If that is happening often when towing, you need to tow in "3" (direct).

 

[kenmyfam]

Re: 1998 Chevy K1500 tranny kicks down too high

There is no passing gear - period. What you are feeling first is the torque converter clutch releasing. If you happen to be in overdrive, the next downshift will be out of overdrive and into direct (1:1). If that is happening often when towing, you need to tow in "3" (direct).

Agree 100% with this. Towing in 3 is a definite plus in some circumstances. Our old Jimmy that we just replaced I towed in "3" constantly. Older high mileage vehicle so i used "3" to minimise shifting and hopefully put less stress on the tranny.

 

[vistacruiser]

Re: 1998 Chevy K1500 tranny kicks down too high

It just means your engine wasn't making enough power at 2000 or so, rpm and needed to go to 3000 to pull you up that hill.
Not to worry, but as the previous posters said, do choose the lower gear any time your trans seams to be hunting for the right gear. You'll probably find you are actually using less throttle at the higher rpm with that load.
Remember back in the old days, 70's-80's, when trucks only had three speed automatics? Third gear is the same now as it was then, 70mph in 3 wont hurt your engine, 2nd gear maybe...

 

[F14CRAZY]

Re: 1998 Chevy K1500 tranny kicks down too high

I like manuals...it does exactly what you want it to do