Gas Mileage Issues

[saaggie]

What's UP!

Hey folks need opinions. I had my stock muffler cut out and replaced with a Magnaflow. I also added the TRD air filter. I disconnected the negative battery cable for about 20 mins to reset everything and my gas mileage has gone down. I was averaging 15 in the city with my V8, now maybe 11. Would the change in back pressure be that severe? I kept the stock muffler and am strongly considering putting it back in.

Any suggestions or comments are appreciated.

Stacy

"Go Spurs"
"Gig'em Aggies"

 

[Koz]

You have increased the flow through the engine. More flow, more fuel.

Koz

 

[Boaz]

Just try to keep your foot out of it!!! I am sure its hard to stay off the throttle with the magnaflow!

 

[MicaBlue03]

Wait a while

With all due respect to boaz and Koz (and I do mean that!) I think there may be something else going on. The engine computer may simply need some time to adapt to the different operating parameters that are the result of changing the intake and exhaust characteristics.

Absent a newly-lead foot, I would expect your mileage to quickly (within a tank of fuel or two) return to something within a few percent of what it was previously. I'd give the system a chance to adjust itself before I put the old hardware back on.

Let us know your results please.

 

[M6HTZ]

I don't think the muffler or the air intake should change your gas mileage. If anything it should improve it. Less restriction is less work for the engine.

I don't have experience with the Magnaflow on the T4R, but I did put one on my Z28 and I didn't see any changes with the mileage unless you consider I was always on the throttle

 

[Koz]

Re: Wait a while

With all due respect to boaz and Koz (and I do mean that!) I think there may be something else going on. The engine computer may simply need some time to adapt to the different operating parameters that are the result of changing the intake and exhaust characteristics.

Absent a newly-lead foot, I would expect your mileage to quickly (within a tank of fuel or two) return to something within a few percent of what it was previously. I'd give the system a chance to adjust itself before I put the old hardware back on.

Let us know your results please.

:iagree:

saaggie,

You may want to disconnect the battery (10 min) so the ECU re-sets and learns again.

I have found that when changing the tone (louder/more aggressive) of the motor you tend to put you foot into it more, to hear that wonderful sound.

By creating more flow you will definitely will use more fuel. It should not be too much. Hopefully by creating more power you can use less foot, but it usually does not happen.

I changed my intake and exhaust on my motorcycle and lost 10 MPG.:happens:

Koz

 

[Mr.yoshimura]

if you reset the ecu it will take about a hold tank of gas before the ecu remap the new setting and goes back to normal. if you did not upgrade your fuel pump/injector I dont know how it could be useing more gas them before.

 

[my04runner]

Funny that you should mention the fuel difference. I thought it was just me. I did a lot of reading before I had my stock muffler cut off. I checked here on the forum and also a few self named "mechanics" and asked the question about the exhaust. Everyone always said

 

[Iowa4Runner]

Re: Re: Wait a while

:iagree:



I changed my intake and exhaust on my motorcycle and lost 10 MPG.:happens:

Koz

You're either riding harder or you've screwed up your bike. This more flow more fuel idea can't explain 10mpg.

 

[saaggie]

Well, I have reset the ECU again. Its been 2 tanks of gas, and I am now at least back to the digital display showing the MPG I had with the stock. I have to pay attention to how heavy of a foot I have. After I changed to the TRD air filter and the exhaust, but before I reset the computer the first time, MPG dropped to 10mpg in the city. I did some highway driving after I reset the computer the second time and my highway mileage was back to 17-18 mpg. Its taken more than 1 tank of gas to get things kinda back to normal. I will keep posting my results.

Stacy

 

[Koz]

Re: Re: Re: Wait a while

You're either riding harder or you've screwed up your bike. This more flow more fuel idea can't explain 10mpg.

By simply changing the intake and exhaust (which included removing the cat) the rear wheel HP increased from 158hp to 171. After tuning the air/fuel mix and timing it jump up to 180.1HP. Again, by increasing the air flow through the engine (pump), the amount of fuel to accommodate this increase can be substantial. Losing 10 MPG is very common when making there modifications.

Koz

 

[Iowa4Runner]

Re: Re: Re: Re: Wait a while

By simply changing the intake and exhaust (which included removing the cat) the rear wheel HP increased from 158hp to 171. After tuning the air/fuel mix and timing it jump up to 180.1HP. Again, by increasing the air flow through the engine (pump), the amount of fuel to accommodate this increase can be substantial. Losing 10 MPG is very common when making there modifications.

Koz

180.1 rear wheel HP? Nice! What kind of bike, a 'Busa?

As for the drop in MPG, you're either riding harder or your carbs / EFI is out of whack somewhere in the operating range. That extra fuel isn't just disappearing.

 

[Koz]

Re: Re: Re: Re: Re: Wait a while

180.1 rear wheel HP? Nice! What kind of bike, a 'Busa?

As for the drop in MPG, you're either riding harder or your carbs / EFI is out of whack somewhere in the operating range. That extra fuel isn't just disappearing.

No Busa is going to make 180 RWHP without going into the engine or adding some type of boost or juice. ZX12R.

To accommodate the increased flow thought the engine as much as 30% more fuel is needed at certain throttle positions and RPM intervals. This is on a stock engine using high tech tuning equipment.

Koz

 

[Lime02sport]

more airflow to the eninge and less restriction to exhaust flow, in no way give you less MPG, you should be getting increased mileage, the motor has less strain now so why would you get decreased gas mileage?

 

[biglatka]

more airflow to the eninge and less restriction to exhaust flow, in no way give you less MPG, you should be getting increased mileage, the motor has less strain now so why would you get decreased gas mileage?

I think it

 

[Koz]

Years ago on motorcycles, to compensate for the added air flow from modifications (air filter & exhaust) the carbs had to be re-jetted (larger jets), why?

Think about this; if you have increased the air flow through an engine by a significant amount, do you think you can use the same amount of fuel and maintain the same air/fuel ratio? Modern engines are tuned on the lean side from the factory, to run cleaner.

Koz

 

[Lime02sport]

the air to fuel ratio is in fact increased by these mods more air flow creates stronger combustion in the cylinders resulting in slight increase in HP, without chaning to larger injectors what would cause your gas mileage to go down? your whole argument is counter-intuitive, besides that your comparing a motorcycle to a car.

 

[Koz]

the air to fuel ratio is in fact increased by these mods more air flow creates stronger combustion in the cylinders resulting in slight increase in HP, without chaning to larger injectors what would cause your gas mileage to go down? your whole argument is counter-intuitive, besides that your comparing a motorcycle to a car.

I used a motorcycle to dramatize the point and to show how changing the intake and exhaust can have a drastic effect. If you don't see it by now, you will not see it. MORE AIR FLOW REQUIRES MORE FUEL. In the 4Runner engine, when you increase the air flow the ECU will compensate by adding more fuel. The factory system will be able to handle an air filter and exhaust change/upgrade. Once the compensating limit of the fuel system is reached you will need to install larger injectors and possibly change the cam profile.

Koz

 

[Lime02sport]

well that makes alot of sense now that you put it that way, i wasnt aware that the ECU can compensate for these changes on its own. thank you for your insight.

 

[Iowa4Runner]

Re: Re: Re: Re: Re: Re: Wait a while

No Busa is going to make 180 RWHP without going into the engine or adding some type of boost or juice. ZX12R.

Koz

No way? Really? 180HP doesn't seem impossible for a well set up 'busa. So you've got a 12R eh? cool. I've been considering trading in my 9R for a 12R, but I'm waiting and hoping Kawasaki will update the design. If the 2006 model is lighter and styled a little better I'll be getting one. Although with rumors of a new large displacement sport tourer, and reports of yet more updates for the 10R, I'm wondering if the 12R has much of a future.