Truck won’t go beyond 90mph after 5.29 Nitro Gear installed

Hello, I am having issues with my truck after installation of 5.29 Nitro Gear. The truck won’t accelerate beyond 90mph or flat roads and highways in South Florida. The truck has a pull and is capped at about 90mph whenever I am doing regular everyday driving to and from work. It feels like the governor kicks in at 90mph. I have done a visual and hearing checked of the truck while driving and I don’t hear or see anything unusual.

The truck runs very well (in my opinion), when it is being driven under 80 miles per hour. The truck hasn’t been fully broken in as yet....It’s just under 500 miles since I’ve had regeared. The only reason why I’ve even taken it up to 80mph is to avoid some close calls driving on I95 in South Florida!! The first time that I had to suddenly accelerate up to 90mph to avoid being ran over by a double tractor trailer that was doing 80mph+ on I95, the truck slowed down and held at 90mph like it was being held by the governor.

My Tundra is a 2017, 4x2, 5.7L. It is lifted 4” and has both front and rear off-road hd bumpers weighing more than 100lbs a piece. I’m running on 35” tires and planed to upgrade lift and tire size. Pull a trailer and a 27ft boat every now and then. Plus, haul around my kids’ trail bikes and other stuff quite often.

I really need your input. Thanks in advance!

 

I have the same gears, but I'm running 37s on my truck. I haven't noticed this issue.... but then again.... it's probably not the safest thing to do with a truck this size. Anytime you regear, you either make it slower on take off/ higher top speed or faster take off/slower top speed. I know that's not exact mechanical talk, but that's the basics. What RPMs are you even at, at this speed?

 

At 90mph, I’m in between 2600rpm-3000rpm. But it fluctuates because the truck seems to be struggling at that speed. So, I immediately slow up to about 70mph. No troubles at that speed. It holds steady at 2000rpm and the truck runs smoothly.

I have the same company installed 5.29 Nitros on my other 2018 trd pro, and I have absolutely no trouble at all. I’m running 35” on that truck and have the same type of bumpers. That truck runs great and I have no issues whatsoever.

strange!!

 

I know what you’re talking about, I’m on 5.29s as well and am on 37s. I think from the ECU perspective the RPM redline has moved down (lower than the display gauge) and it’s actually really easy to trigger the governor - I was doing it quite often and have come to the realization that I can no longer mash it. I believe this problem will go away, for me, when I upgrade to 39s.

 

Hitting the governor probably. There are 2 different mph settings that I don’t recall right now used depending on original tires etc., probably have the lower one vs your 18. Tuning needs adjusted for gearing and tire size, but that does not fix speedometer. Wouldn’t install 5.29 gears without the ability to adjust the calibration accordingly. Can mash mine anytime, it’s impressive.

 

Did you tune yourself or have a shop do it? I need mine done.

 

I was hoping that it’s the governor and not anything else. Do you have any idea if going to much bigger tires will solve the problem?

 

Myself, with HP tuners.

 

What tire size are you running? I’m going to put my BD Tuner on it tomorrow to see if the problem will go away.

I have 20” wheels on my truck. It came with 20” wheels and I upgrade to 20” aftermarket wheels. What’s your current setup?

 

Right now my truck isn’t tuned. I wanted to wait until I broke in the new gears before putting the BD tuner on it. But, I think that I’ll go ahead and add the tuner tomorrow then add a few miles on it to see what happens.

 

Does the HP tuner allow you to remove the governor and adjust for gears and tires?

 

LT truck on 37” tires.

Can you adjust gearing, tire size, and mph limit with BD? If so should be good to go. Yes can adjust governor for gearing and tire with HP. Not sure about the speed limiter, correcting for gearing and tire in the calibration still leaves speedometer reading wrong, not sure if the wrong reading is still the limit? Didn’t matter for me, just set the mph limit faster than truck will go.

 

Yes, the BD GT can remove the governor and change transmission shift points. But, it doesn’t do much with gears and tires, I believe. It’s been a while since I checked it’s updates and capabilities.

 

What model HP Tuner do you have?

 

hate the governor..that thing needs to be gone.
when you need to punch it, the governor is unsafe imo.

 

Tell me about it. Almost everyday commuting to and from work, I have had to punch the accelerator to save my life. People down in South Florida can’t drive for shit!

I really need to remove the governor and tune for gearing and tire size.

 

The governor shuts me down at 90 too with 5.29s. However, with 37" tires I'm actually doing well over 100, verified with GPS speed. I do need to tune mine like @Vizsla though 'cause some places in the desert it'd be nice to go a wee bit faster.

 

Agree. It’s fun without it.

Crap Warren, had no idea. We need to fix that. My truck takes off like nobody’s business at 90 mph.

 

Yes please Dave! Think I'm ready for some advice from you on what I need to purchase.

 

Interesting. I never heard anyone say that the governor capped them with their 5.29 gears before now. I must not have been paying attention to that part of the discussions. I need to remove the governor, first and foremost. I’m going to go bigger tires too.

 

Does your truck go above 90mph?

 

Same here!

 

Hmmm I remember you smoking me in the mountains Warren. I couldn’t keep up with you cuz the stupid governor was kicking in.

 

Googled "HP Tuner Tundra" and found Viktor's thread. All you basically need to know https://www.tundras.com/threads/instructions-for-custom-tuning-the-truck-with-hptuners.70590/

Also looked up what HP Tuner supports:

 

Just went to https://www.hptuners.com/mpvi2/ and purchased the MPVI2 with 4 credits. Can't wait!

 

To address our specific issue it looks like we just need to enter the tire radius and new gear ratio as shown in the image here: https://www.tundras.com/threads/ins...truck-with-hptuners.70590/page-2#post-2204359

 

That’s funny.

 

@Cruzer Thanks for the information. I’m definitely going to get the HP Tuner.

 

I’m on it too!

 

I’m wondering if our trucks will throw CEL if we removed the governor, because the VSC will also be affected.