Resetting ECU on 5th Gen?

[On Point]

I have a theory about the drop in my MPG and I believe it to be related to the ECU.

After I installed the GOBI roof rack, I noticed my MPG dropped approximately 1-2mpg depending on city/hwy driving. I removed the rack a few months later and expected to see the mpg increase... it never happened. I used to get 21mpg+ easily on long distance trips, but my last trip yielded 18mpg.

I'm wondering if resetting the ECU to when the car was purchased will help. I may be completely missing the mark, but thought someone more versed could chime in. Any thoughts?

 

[Friggin Idiot]

Disconnect the negative terminal on the battery for 2+ hours.

 

[2016 4Runner SR5]

Or just simply reset the MPG counter on the dash. Select that display, press and hold the selector switch, it resets. You should reset this every fill up if you want to be somewhat accurate.

 

[Friggin Idiot]

Or just simply reset the MPG counter on the dash. Select that display, press and hold the selector switch, it resets. You should reset this every fill up if you want to be somewhat accurate.

That will only reset the MPG counter, it won't reset the ECU.
The ECU basically has 2 ways to compute fuel load and timing, table or learned. Table is the basic table from Toyota that is always a fail-safe, although not always the most accurate for conditions. Hence the ECU also has the ability to "learn" timing adjustments and fuel load based on real world performance. This gives it better ability to adjust for air density, altitude, humidity, temperature, etc.
Resetting the ECU will clear the learned data and force it to revert back to the table mode while it adjusts to new conditions. Resetting the MPG computer does nothing but clear the displayed MPG and force it to calculate new MPG.

Any time you change fuel type, you should reset the ECU. Switching from 87 octane to 93 octane, or 10% ethanol to ethanol-free. Although because of it, I would only reset the ECU if you intend to continue running that type of fuel, not just a single tank.

 

[NJSalsaRed]

Resetting the ECU will only clear error codes. The ECU is constantly monitoring air fuel ratios and many other parameters and making adjustments continuously to achieve the required preset A/F ratio. Resetting it will do nothing to it's operation.

If you have a drop in mpg, look elsewhere to find it. Aging o2 sensors, tires, dirty maf, air filter, fuel, driving habits, etc.

 

[wfo9]

Resetting the ECU will only clear error codes. The ECU is constantly monitoring air fuel ratios and many other parameters and making adjustments continuously to achieve the required preset A/F ratio. Resetting it will do nothing to it's operation.

If you have a drop in mpg, look elsewhere to find it. Aging o2 sensors, tires, dirty maf, air filter, fuel, driving habits, etc.

Yes and No. It takes it a long time to learn some things...So if you have bad fuel in it for a while... It can take a long time for it to react to good fuel... Same with a dirty MAF or whatever....

Also, there is no way to reset it without a full re-flash that I know of... The battery disconnect does not do much.

I think the most common difference people see is fuel with or without ethanol... winter vs summer blends..... These have big impact on MPG. High vs low octane will also have a decent impact, but that takes time for the ECU to adjust.

 

[tristero]

Also, there is no way to reset it without a full re-flash that I know of... The battery disconnect does not do much.

I assume you have to reflash with the SC, at least at install. Is there any simple way to run a re-flash without OVTune?
I wish the T4R crowd could get some attention from them....

 

[2016 4Runner SR5]

Yes and No. It takes it a long time to learn some things...So if you have bad fuel in it for a while... It can take a long time for it to react to good fuel... Same with a dirty MAF or whatever....

Also, there is no way to reset it without a full re-flash that I know of... The battery disconnect does not do much.

I think the most common difference people see is fuel with or without ethanol... winter vs summer blends..... These have big impact on MPG. High vs low octane will also have a decent impact, but that takes time for the ECU to adjust.

So running 93 will achieve better economy? I've seen quite a few "tests" that basically say it stays the same. TBH if I can get a little more power and better economy out of 93, I'd be happy to start using it for the marginal difference in cost.

 

[Travelin]

Might be too simple-minded, but why not keep a paper record for a few fill-ups to see how well the computer is estimating average MPG.

In any event, this is certainly correct:

Or just simply reset the MPG counter on the dash. Select that display, press and hold the selector switch, it resets. You should reset this every fill up if you want to be somewhat accurate.

 

[2016 4Runner SR5]

Might be too simple-minded, but why not keep a paper record for a few fill-ups to see how well the computer is estimating average MPG.

In any event, this is certainly correct:

To be honest, I don't care enough lol. I bought a truck, lifted it, put 90 pounds of wheel and tire in each corner, I knew what I was getting into. If I can improve MPG I'm all ears but not at the cost of changing my rig. If 93 would help and give me a little more power, I'm all for that.

 

[wfo9]

So running 93 will achieve better economy? I've seen quite a few "tests" that basically say it stays the same. TBH if I can get a little more power and better economy out of 93, I'd be happy to start using it for the marginal difference in cost.

Yes it will get better economy and power. How much is what is in question. How long it takes for the ECU to adjust is also a guess.

The main difference is how much timing can be run without knock.. but this is all depends on how clean your intake is and many other factors.

Don't know how accurate this is, but 1grfe wiki states 270 hp (201 kW) at 5600 rpm and 278 lb⋅ft (377 N⋅m) at 4400 rpm on 87 octane and 285 hp (213 kW) and 289 lb⋅ft (392 N⋅m) on 91 octane

If you can run ethanol free... you will see a good bump in mpg. Around here, it is really hard to find ethanol free, but I understand it is common in some parts of the country.

 

[2016 4Runner SR5]

Yes it will get better economy and power. How much is what is in question. How long it takes for the ECU to adjust is also a guess.

The main difference is how much timing can be run without knock.. but this is all depends on how clean your intake is and many other factors.

Don't know how accurate this is, but 1grfe wiki states 270 hp (201 kW) at 5600 rpm and 278 lb⋅ft (377 N⋅m) at 4400 rpm on 87 octane and 285 hp (213 kW) and 289 lb⋅ft (392 N⋅m) on 91 octane

If you can run ethanol free... you will see a good bump in mpg. Around here, it is really hard to find ethanol free, but I understand it is common in some parts of the country.

I have never seen ethanol free in Maryland but we do have 93 pretty much everywhere. Intake should be very clean since I have just over 10K miles on it. Also have a catch can which seems to do a damn good job at catching at least some of the crap that would otherwise end up in my intake. I'm on a full tank now but once i'm low, I will start running 93 and see what happens. Can't hurt anything so why not.

 

[gdvan01]

I have never seen ethanol free in Maryland but we do have 93 pretty much everywhere. Intake should be very clean since I have just over 10K miles on it. Also have a catch can which seems to do a damn good job at catching at least some of the crap that would otherwise end up in my intake. I'm on a full tank now but once i'm low, I will start running 93 and see what happens. Can't hurt anything so why not.

Here ya' go, homie...

https://www.pure-gas.org/index.jsp?stateprov=MD

 

[2016 4Runner SR5]

Here ya' go, homie...

https://www.pure-gas.org/index.jsp?stateprov=MD

Thank you! Figures there are none near me though lol