Real World Info for guys thinking about 4.30's

I love this post.

"I know this can be considered vanity, but after so many mods/$$$ spent it doesn't seem too bad."

Could not agree more bro

Once you start calculating costs of mods, a few hundred really isn't that big a deal. Could you do me/us a favor? Assuming you have larger tires. Since you just installed it, can you take note of performance differences since install?

 

I got mine used on eBay for around a hundred dollars, so it wasn’t crazy $.

 

Let me try to put the air/fuel issue into another perspective.

Let's say...

You have a rear third member in your yard that you want to toss into the trash. That's about 70 pounds depending. And hard to handle.

You maybe super man, I'm not.

So, picking it up and carrying it to the blue can (from experience) makes me exert about all my strength!

So when I do that, my body sends signals telling my muscles to exert alllll my energy!!! Leaving me worn out.

But, one day, after wasting all that fuel, when I think i am only half way to the trash can, I realize, I'm actually at the trash can! I can drop the weight and rest!

What happened is, no one forgot to tell me, that on that specific day, my house was relocated to the moon. I didn't need to spend all that fuel to do the same job. (it's an analogy).

In other words, no one is telling the ecu that it's load just got alot less, adjust accordingly.

 

I honestly dont think theres anything to gain from the ecu knowing the true speed. If anything itd shift earlier than it already does.

 

A/F ratio is determined by the O2 sensors in your exhaust and the mass air flow sensor in your intake not the gear ratio of your rear end. The engine is going to run at the optimal AF ratio whether your truck runs at 2000rpm at 60mph or 4500rpm at 60mph. If you’re really that worried get something to monitor AF ratios and I bet they be the same before and after regearing.

 

Hypertech response to inquiry is not too encouraging....



Hypertech’s In-line Speedometer Calibrator Module is an in-line module to correct the speedometer and odometer for non-stock tire sizes and/or rear gear ratios. This module is perfect for vehicles with computers that don’t allow for tire size and/or rear gear ratio correction or re-calibrate for tire sizes and/or rear gear ratios outside the range of programmers.

Speedometer Calibrator

If you’ve installed tires that are larger or smaller than original equipment tires, or if you have installed a ring and pinion gear set with a different rear gear ratio, the Speedometer Calibrator allows you to correct speedometer and odometer readings. The vehicle’s computer calculates your vehicle’s speed based on the diameter of the stock tires. If you’ve installed taller or shorter tires, or changed the rear gear ratio, the vehicle’s computer doesn’t know how fast your vehicle is going. As a result, the speedometer readings will not be accurate (as required by law).




Using the USB cable connect, the In-line Speedometer Calibrator Module to your PC and enter the new tire height and/or rear gear ratio. There are no limitations for increasing tire height or rear gear ratios. Next, disconnect the factory connector to the instrument cluster (behind the dash), snap in the Speedometer Calibrator Module, reconnect the cluster, and you’re done! In a matter of minutes, you can accurately correct your speedometer and odometer readings (as required by law).



Tech





Which is exactly word for word the useless explanation on their website.



I do see you guys point about a/f, but what I'm trying to put across is that if it's not shifting right, your running the the wrong RPM's at speed, the ecu is dumping fuel thinking it needs to catch up, but it's already there... Follow???? I responded to Hypertech, we will see....

 

Sorry man, that’s just not the way it works. There’s no fuel dump, or need to catch up. What I think you’re thinking is that the engine is spinning at higher rpms at a set speed versus the stock gears, but remember you already have larger tires bringing your ratio back to target provided your gears and tires equate back to stock ratios. Thus no real effect to performance other than the added rotational mass of the larger tires.

You’re right that the hyper tech only impacts the speedometer, and odometer for the driver. But that’s usually important to have correct. Or not, that works too.

 

Are you saying the transmission is holding gears longer and not shifting at the correct rpm?

 

But that's not what Hypertech claims. Read it carefully. They mention gear ratio and shifting, which leads to believing they are doing more than a smoke screen. That's what I want to know and for the record they are refusing to answer the question.

For speed, even running a complete OEM truck, you should use GPS speedometer. From the factory they are off a good bit. About 1.5MPH at 70.

 

One symptom, yes. And I think shifting is a big one. Another oddity I picked up on is charging. After regear, voltage drops are less. Now, at full draw, I can only draw voltage down to about 11.7 while driving, still need to upgrade, but before, larger alternator and second batt, was on top of the list. Only had maybe 10-15mins of full draw and shut downs start. Now, I just see power droops, so it's a livable problem, can hold off a little longer on spending the money.

So it's got to be shifting based on what the ecu speed reading is.

 

While speed does play a factor into shifting points there are also other data points the ECU monitors to provide optimal shifting points. Such as throttle position, load on the engine, speed, your current gear, if youve been towing the ECU will learn to hold gears a bit longer and I’m sure there are more that I’m unaware of.

You can spend a lot of money of a fully programmable ECU and change the speed that it’s seeing but I feel like it won’t change anything and it will drive just the same.

As for the hypertech all it does is change the displayed speed on your speedometer. It reads the incoming signal from the ECU and then modifies it based on the tire size you programmed into it. Hope this helps

 

The ECU adjusts A/F ratio based on engine load and O2 sensors. Engine load utilizes the Air Intake Sensor (IAT), Manifold Absolute Pressure (MAP) sensor, Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) sensor to do calculations. Your tire size vs. speed idea is all wrong. The reason your seeing less voltage drop is because your RPM's are higher now. More RPM's = more voltage out of the alternator.

 

1100 miles on the clock since 4.30's and TrueTrac. Adjusted MPG (meaning GPS not odometer), with tires actually measuring 34.5, 13.6MPG highway running 80MPH, 13MPG city. At 2400RPM's 80MPH with 5 speed automatic you are maxed out. After that, additional speed is at cost of additional RPM's. At 2900 RPM's I hit 90MPH (GPS) that's as far as I took it!

The tires are 325/60/20 approx. 35.4", but measure 34.5". So for example, if your running BFG 35x12.50 you actually running closer to 33's. So your RPM's would be higher.

Also noticed Long Term Fuel Trim was running rich. I run a 2009 FJ 1GR-FE engine. So I swapped the Tacoma air fuel ratio and O2 sensors out with sensors that matched the motor. LTFRT got worse, from like -.8 to -2.8. Hense milleage got worse, so swapped back to Tacoma sensors.

The take away here is with 35's and 4.30's

- expect about 13MPG (which is pretty freaking good!)
- don't expect to go too fast on the interstate or RPM's start climbing
- we are losing gas mileage until we can get the ECU to control the air fuel ratio correctly
- if I was going to run 35's, would I go with 4.30's over 4.10 or 4.56? It depends. If you never go on the highway, 4.56 will work. If your tires measure under 34" I'd go with 4.10's. If your tires measure over 34" and you drive on the highway, I'd go 4.30.


Now, need some input from you guys about TrueTrac. When I take off from a stand still on pavement making a turn, half way through the turn it's engaging if your I'm accelerating. Is this normal?

 

I've got 33" Federal MTs on the truck now with stock gears (3.73 as far as I can tell) and the truck behaves fine. Has plenty of power, sits around 2100 RPM @ 70 on the highway, but MPG is terrible. I haven't measured exactly because the odometer is off but I think it's around 15 or so. Would 4.30s improve that?

Also, been seeing you around town. Slick truck man

 

Hey Joseph, maybe I missed it, but what eng. & trans do you have? I have a 4X4, 2.7 W/ auto & looking at re-gearing to 4.88, to try & help the sluggish feel & shifting all the time.

 

Thanks for the heads up. I want to go this route but with MT.