Having a issue… RPMs

Hey guys, I have a 2020 Tundra 4x4 that I baby other than the occasional off roading/over landing. Ive been having some trouble with my truck lately. Took it to the dealership, they are saying it’s all normal. Lets break it down

A couple weeks ago I began having an issue with my RPMs jumping at downshift. Seems like whenever I pass through a gear on the way down to idle my RPMs jumping up a crazy amount. Usually never the same either. Instead of the usual downshift jump of 50-100 rpms we’re talking a downshift jump of 300-700 RPMs. I was told by the dealership that it’s normal but my truck has never jumped that high. Only the usual 50-100. There is no loss in power nor is there any stalling, it’s almost as if the truck gets stuck in that gear for a second. Once I completely stop the vehicle I idle at a normal level of about 600-750. Truck only has about 39,000 miles, a bit early to be having issues with a tundra if you ask me. Sorry if I rambled lol, any help would be appreciated!

 

Post a video on YouTube, link it here.

 

Change transmission oil.. may be time, not mileage but time.

 

Ok I’ll post a video when I get a chance.
Yes I was also thinking of doing a transmission flush.

 

RPM jumping 300 to 500 sounds normal to me when truck is downshifting.

 

Question on this? I know it’s normal for the RPMs to jump during downshift. However should the truck feel like it’s kinda shaking when it happens?

 

Are you in Tow Haul mode? Or S mode when this happens? Peddal Commander? Did you mess with your ECU at all?

 

Tow Haul, no
S mode, no
pedal commander, no

ECU yes, a couple months back a remote starter. Was installed by a reputable shop locally. Everything worked fine when they installed it. Toyota dealership said that it wouldn’t cause any issues. Problem started several months after. Now going off of this theory idk if maybe some of the wires they spliced are perhaps loose or grounding to something.

 

That doesn't sound normal to me. I don't see rpm's jump around before settling in or overshoot. What you are describing almost sounds like there's some slipping going on right before gear engages? either way, if it wasn't doing so before and doing it now, it definitely isn't okay.

When I pass and transmission has to downshift two gears, it just goes
rrr---Trrr---TRRRR!!!

 

I feel a little bit of extra pull from the down shift, that ever so slightly makes me feel my body be pulled forward as the rpms jump some and I feel the truck slowly down faster from having to spin the engine RPMs up.

 

Try disconnecting the battery while you clean the throttle body thoroughly. If its dirty enough to throw off idle rpm load it might mess with other things.

 

Wish it was that simple… my original thought was that the throttle body was dirty or the mass air flow sensor had gone out. I cleaned the throttle body really good and replaced the MAF sensor. Still happening.

 

I agree however every place I take it to seems to think it’s normal. I don’t think my vehicle downshifting so rough you can feel it is normal. Whether the RPMs are still in the normal range or not there is absolutely still something going on.

 

Does yours shake slightly during downshift though. Enough to make you feel it?

 

I’ll work on getting a video in here tomorrow so people can see what I’m talking about.

 

Hanging on gears?

 

Perhaps… it does act as though it gets stuck on some of the lower gears. I’m not mechanically inclined enough though to tell if it’s a mechanical or electrical issue. My theory is an electrical issue from the splices they made to the ECU for a remote starter a while back.

 

You may need to check the fluid level. Odds are it's slightly low. These transmissions are temperamental if low or over. Drain and fill may assist if you haven't done so already. Lifetime fluid is a lie, so find an interval and replace either once every 20k or 30k depending on the fluid.

 

Well I have good news. A lot of people were mentioning the ECU so I went ahead and checked it out. When I looked at the ECU I decided to check the splices made for the remote started several months ago. Apparently the shop that installed it used super low quality crimp connectors which cause the wires to not have a stable connections. I cut out those crimp connectors and braided the wires together and sealed everything in up using some heat shrink. My truck is officially back to normal running like a champ. Everything was caused from those wires not having a good connection. Left the negative on the battery off for about 20 mins to allow the ECU to refresh and reset values and we were good to go. Thanks for all the help and ideas guys!