trans wont coast

I been noticing that when I let off my throttle my truck shifts down out of over drive. Is this a computer issue or trans n what can be done to fix it. I read something that when it truck is coasting the injectors shut off for fuel saving except I can't do that cause I just slow down.

Also it hardly ever wants to go Into over drive I know the 35's don't help but on level ground with nothing really holding the truck back just cruising once it gets its momentum it should go into 5th then od correct it has 60k miles now on the truck n I doubt the trans was ever flushed or had its fluid changed would this solve my problem possibly?

Any and all advice is appreciated thanks

 

this is something normal, when you let off the gas the truck goes into full fuel cut for better mpgs.

You can get the truck to "coast" that is feed the engine some fuel by simply letting the gas off, then moving the shifter from D to N back to D. The truck will come out of fuel cut and "coast" That is untill you get back in the gas and let off again.

These trucks lug the motor quite a bit cruising, unfortunately its not a v8 with boat loads of torque down way low, so with 35's its gonna be hard to hold 5th in lockup, unless you regear.

Id recommend a flush of the trans either way.

 

Some of this has to do with deceleration fuel cut off. The major majority of it though is because the transmission was designed to perform something called engine braking under decline conditions. The idea behind it is that it will save you from excessively braking. This is normal and there is nothing you could do to change it, given Toyota computers are very difficult to modify.

 

Thanks guys this is very informative

 

yes, the engine goes into fuel cut and makes it to where you cant "coast"

the other thing you describe is if you ride the brakes on a downhill the ecu / trans sense this and will downshift from 5th to 4th, etc.

On my way home from work there is a hill that the truck will downshift to 3rd for me, its nice.

You can also move up ONE gear at a time from this auto downshift(s) by moving d to 4 back to d. I do this to step up from 3rd to 4th, then 4th to 5th on the downhill so i dont have to touch the gas to get it to upshift.

You can also go straight from say the auto downshift say from 3rd back to 5th coasting (no fuel cut) by again doing D to N back to D

The auto trans does a DAMN good job if you know how to use it.

 

Interesting stuff here. I just had a hell of a time trying to TV mount a soundbar so I might have to revisit this info tomorrow because it sounds like it's something I could benefit from.

 

^This is what I've found. If you just left off it's as if it's slowing down with the gear, rather than coasting in nuetral (comparing to a manual of course). If you left off the gas, then give it a slight tap it'll coast really nice. I like it, more user input, like my old 5-speed.

 

tapping the throttle after letting off it takes it out of fuel cut. I found it to not be as predictable as doing the D to N back to D as sometimes you would tap and it would come out of fuel cut but then go back in (verified on the OBD reader). But i dont often feel the need to "coast" so when i do its easy to tap the shifter around.

 

Yeah, the shifting method is a bit much if you like to coast. I'm constantly trying to coast into stop lights and down stretches in traffic. Less pedals, better MPGs... Just slight taps and it coasts good, but you're right not EVERY time. I'm getting better at finding the sweet spot.

 

Learn something new everyday. The instant rpm drop when letting off the throttle gave me the impression there was just a lot of drag.

 

you will actually get better mpgs if you let fuel cut do its thing and not coast as no fuel is being fed to the motor during fuel cut. So dive for a bit longer then let off the gas and let the engine braking and fuel cut do its thing.

You can stay in fuel cut down to ~20mph and you can actually feel it come out of it.

 

Ok, so it'll engine brake till 20mph then coast on its own?

 

Sure enough, it stops engine braking at 20mph and coasts. Thanks for the tip!

 

The fuel cut is something I've never understood. When you say "no fuel is being fed to the motor" how is that possible? The engine is still running (at lower RPMs), if no fuel is being used wouldn't the engine detonate?

I'm not trying to be a smart ass, I just don't understand how that is possible.

 

^ haha yup. You can actually feel it around 20mph when the engine starts to get fed fuel again, almost like you got a lil bump from behind.

 

What do you mean by "verified in the OBD reader"? I've never noticed anything showing me what head or if it's in over drive?

Does anyone know if the trans splits gears? Like 4th n 5 it seems like when havin to shift down slightly it dosnt go completely down a whole gear just like a little rpm boost.. anyone no what causes this..

Seems to me like it splits gears like my 16 speed rig with spliter

 

Verified by OBD meaning i can see the current fuel flow, and during fuel cut fuel flow is 0 cc/min vs coasting where fuel is fed to the motor.

The trans does not split gears but can feel like it in 4th and 5th gear due to the torque converter lockup.

 

It may not be O/D it's probably just coming out of lockup that's normal.