Jake brake feeling

ok so this has been happening since day 1 and naturally the dealer doesnt have anything to add/help. mainly i was just wondering if anyone else has the same "occurence" as mine.

ok so i have a 2011 4X2 4cyl access cab.

it happens in the morning, it doesnt matter whether its cold or not outside just before the truck warms up. as the truck decellerates and the rpms drop from 1100-800, the truck does a "shudder" deal. the only thing i can compare it to is the feel of the engine braking or if you roll over a small rumble strip on the side of the road.

again its not really bothering anything im just curious if anyone else has experienced this or if im unique

 

bumpppppp

 

is it more of a "feel" or a sound? i have had something similar (i think) happen to me too

 

its a feeling. but it happens just about every time after its been sitting for over 6-7 hours (night) and before the temp gauge gets above the C (cold)

but also this may just be a 4 cyl thing. ive never driven a 4 cyl before this truck

 

sorry man don't think i can help ya out. good luck

 

that sounds great and all and it makes sense but are you talking about like if you have a stick shift and you downshift to to slow down and the rpms jump UP to slow you down?

the reason i ask is that it feels almost like the opposite. almost as if your trying to start out in 2nd or third. but the (automatic) truck is decelerating...

still not sure if im explaining this in an effective way or not...

 

It might just be the way the transmission downshifts at that speed. I drive a 5 speed so I can't say I've experience exactly what you're describing though.

 

I had a Dakota that would do that only when cold. It was a sticking Idle Air Control valve. The Tacoma doesn't have that, but I suppose you could have a sticking electronic throttle body.

I have a four cylinder Tacoma at work, but it's a 5 speed.

 

It the feeling just for a split second and usually around 15-20 mph? I have felt almost the exact same thing you have, complete with the very muffled rumble strip sound.

 

WOOO im not alone!

 

I feel the same way brother, it's not going to bother me at all now that I know my truck is normal

 

my tacoma, 11' I4 5spd, does get a shudder sometimes when I first start, and sometimes when I stop at a red light or stop sign right after I come to a complete stop..

 

haha funny that you posted this. mine does the same thing in the morning if i have to stop at the first light. once i get down to about 15 mph it does a quick shudder as I'm slowing and doesn't do it again until the next morning.

 

yup thats it! just once a day. at that first stop sign.

 

Yup me too, once per day, usually just before my first complete stop. It kind of feels like the fuel cutoff engine braking feature, only much stronger and at much lower RPM.

 

I have the same thing, my dealer said that since the vehicle is cold, it is still enriching the fuel into the engine. If you were in neutral it would be idling higher than it does once it is warm. As you slow down to stop, the extra fuel keeps trying to keep the idle a little higher so it is sort of like if you had a manual transmission and tried to give it gas in too high a gear, it is basically lugging for a second before the automatic drops out of gear. They said it is more noticeable on newer trucks because the automatic stays engaged longer as you slow down to help emissions. But once it is warmed up there is less fuel so you don't feel it then.

 

That makes total sense to me... thanks for the education, and to your dealer/tech as well.

 

that does make total sense! now i have an explanation finally! im glad someones tech is smart in the way of how engines/trucks work...

 

Mine does the same .... mine is a 2012 base, 4L 4X4 Auto ~4K miles. The Solution /reason stated makes sense. one other possible issue that "might" be a cause (although I do not believe it is so in this case) .... a Bad/leaky vacuum booster on the power brake could steal enough vacuum to cause the rough engine vibs .... leaks when cold and you step on the brake ...

 

Just to correct some misinformation here, the computer can and does sometimes prevent shifting into the higher gear when it is cold, but it does this to help warm up the transmission fluid, not to help warm up the engine.