High RPM on highway

2018 Tacoma SR 4-cyl 6AT

I purchased from the original owner a couple months back with about 55k miles on it.
They put on a leveling kit to allow slightly larger tires (to my understanding of the purpose of a level kit).
According to my Toyota app, the truck originally came with 'Hankook 16R245' whereas it now has 'Cooper Discoverer Maxx LT265/75R16'

I took it on the Interstate for the first time this weekend, and for the majority of the 600 mile drive, I was constantly bouncing up to 4K rpm to maintain speed. Didn't seem to matter if I was trying to maintain 75mph or 90mph. Never really seemed to drop below 3.2K the whole time.
(I am driving Montana Interstates that are far from flat and involve a lot of hills and mountain passes)

For the first 300 miles I had the truck in D the entire time. On the return trip, I tried a few times to switch to S mode and manually shift into 5th and 6th gear while going 80+mph. When I would manually shift, RPMs would drop for just a fraction of a second and then jump right back up to 4K. The dash would show that I was in 5th or 6th, but it didnt seem to act any different regardless of if I was in 4th, 5th, or 6th.

It seems pretty drastic for a small level kit and slightly larger tires to cause that much strain on the engine, but could that be what is causing the issue?
What else could I look into?

 

Do you use the ECT function? That runs higher rpms. Didn't think it would run that much higher but maybe?

 

welcome,
sounds about normal to me. You have a bad combo of high speed/wind resistance in a heavy brick, two overdrive gears that already require shifting, the weak I4, and lift/tires to make it struggle even more. In other words: it was probably doing this stock.
By comparison, my V6 with stock tires and no lift would need to shift often to maintain highway speeds in 70-75 mph range,,, let alone pushing 90 mph. Throw a headwind in there? and all bets are off!

 

Don’t know if that’s normal for 4 cylinder or not and can’t be much help there, but s mode is an upper gear limit. What is displayed on the dash isn’t what gear you are in, but the highest gear the transmission will shift into

 

those look like mud tires. that combined with a 4 cylinder means you are going to running high RPMs especially in the hills. you could also reset the learned values so it learns your driving style and not the previous owner's. higher octane fuel may help a bit but it takes a few thousand miles to fully adjust to it unless you reset all the learned values/fuel/throttle trims. I would also replace the air filter and spark plugs and get less aggressive tires. Make sure they are the same size as the OEM tires and not larger. Replace the differential fluids will help a little as well by decreasing rolling resistance. and it never hurts to do a drain and fill on the transmission despite what the dealerships will tell you.

 

I don’t have the 4 cylinder motor but I experienced similar issues when I was in Montana (ironically) last month. My truck is tuned but the tune doesn’t work when the truck is in traditional “constant speed” cruise control.

If I tried to use the cruise control to maintain speed during mountain passes, the truck was regularly running above 5K RPMs. It felt like the engine was going to explode (I know it wasn’t) so I had to avoid the constant speed cruise control during the mountain passes.

I did not have these issues without cruise control (so, no issues when my tune was controlling the shift points). I say this because it was clear that it was an issue with the stock shift points. If that makes sense. It could just be the crappy shift points that every complains about with the automatic trans in the 3rd Gen.

 

@bkhlrTaco's - No ECT was not enabled

@musicisevil - Thanks for the info on the S mode display. That is good to know.

@cryptolime - Yeah doing some research I am seeing that that is the BIGGEST size tires they recommend for the susp. on the truck as is ha

@ROAD-Warrior - Yes being in cruise-control definitely made it MUCH worse, it would constantly bounce between 3.5 and 4.5 rpms trying to maintain speed. Not in cruise was certainly better, but still annoying to contantly be jumping up just to maintain the speed limit.

 

S mode doesn't show what gear it's in. Just shows what gear it stops at. If it reaches that higher number gear you can downshift it manually but if your going 5mph and put it in S mode to 5th it will not be in fifth. just works like an automatic

 

It's a combination of elevation and hills, 4cyl 169hp and bigger than stock 245/75R16.

 

I don’t think I explained my theory properly lol

Basically, I think a tune might help you. I could be wrong because I’m not an expert. I’m not recommending you get one, just making an observation.

When my tune was controlling the shift points, I stayed under 3.5K RPMs even at high speeds on mountain passes.

When my tune was not controlling the shift points, I was regularly stuck above 5K RPMs at high speeds on mountain passes.

Unfortunately these trucks don’t have a ton of power so I don’t think there’s anything wrong with your truck. It’s just kinda the way they drive. A lot of people get their trucks tuned to fix that issue.

 

@Road_Warrior
I follow ya now. Thanks for the advise good sir

 

Anytime! Hopefully it helps.

 

All I've been told that anytime you run over 3k rpm for extended periods it's not good. You shorten engine life, especially the valve guides.

 

Zoo truck: Not necessarily; depending on the engine, 3-4k might be the sweet spot.

It definitely sounds worse, and feels kike you're overworking it, but the motor actually runs better and easier at those speeds (that's why it downshifted in the first place).

Yes, you're running at higher speeds, but air is flowing more freely, and the engine is designed to run up to almost 6k on a regular basis. If you have a scan gauge or similar, you can see the engine typically runs cooler in a lower gear under the same load.

If it were my truck, I'd either slow down (easier said than done in Montana) or put some stock size tires back on it (at least passenger tires, and not super heavy LT Maxx's). Not sure if the 1" lift makes a big difference, as these trucks are already not very aerodynamic.

245-width passenger tires should make a big difference at any speed.

Edit:
Your tires are 55 lbs each. Same tire in stock size is 47 lbs.

You can get stock size Wildpeaks (which are actually considered a heavy tire) at 39 lbs, non-LT. I run these, and they are pretty solid on road, with good performance on gravel / dirt roads and the occasional snow.

Or my all-time favorite highway tire, Michelin Defender LTX, at a svelte 35 lbs, non-LT. If you don't off road, it's hard to go wrong with this one. You'll see the best MPG and road performance with these.

 

2tr-fe needs to rev up. No worries there

 

This site is awesome. Shout out for all the quick replies!!

I should mention, that of course I would expect it to be revved up pretty high on the hills and especially mountain passes.
It more-so was the fact that even on relatively level roadway, it cant seem to maintain a speed above 70ish without constantly having to jump down a gear and rev up to that 4K mark. Just annoying to have to listen to that every 15-20 seconds ha.

Starting to sound like its fairly normal and that bigger sized tires are definitely not doing me any favors. However, it is comforting that it doesn't sound like a transmission issue or something more serious.

 

Go down to sea level and drive it on a flat road.... these things lose power as you get higher in elevation. Tires def holding you back too. All normal stuff. Nothing wrong with the vehicle.

ECT + sport mode + trac off helps a little but it won't turn the 2.7L into a big block v8.

 

Tire diameter is not the only thing that you need to think about. The rolling resistance of a LT commercial all terrain tire is going to be significantly higher than the stock P all season tires of the same size. You’ll likely an if you go back to stock-specced tires. You might still be unhappy with the 4 banger, but things should improve.

 

Yes, I'm sure you would find an immediate difference with stock tires and wheels. And yes as others have said the 4 banger is a little light on power.

 

Seattle is a day or so drive ( a nearest sea level spot...)