Why didn't headers make any power?

[KorovaB2]

Speaking of which, I've driven about 500 miles and I'm definitely feeling them now. I was surprised most on how tender that gas pedal became. When I put my foot down, I GO!

[Dude Boy]

Originally Posted by RockyMtnRay

First of all, the Tundra's stock ECU (PCM) is generally not considered tunable...certainly not by your neighborhood tuner...Toyota has never released the code needed to tune it. Only the aftermarket units (Unichip) can be tuned. Allegedly Jet has broken the Toyota code but I have major doubts about how well they did it.

And in any case, tuning is simply not needed after header (or intake install). Yes, the headers do necessitate some A/F ratio adjustment but the stock ECU self-tunes itself by comparing inputs from the Mass Air Flow sensor/stored fuel maps to inputs from the 02 sensors. It adjusts the mixture so that the 02 sensors show proper (14.7:1) mix in closed loop operations and then stores those adjustments in the short term fuel trims. On each shutdown, a percentage of the short term fuel trim values is transferred to the long term fuel trims. On each start, the long term fuel trims are applied to the stored fuel maps to produce the initial mixtures...and then the process starts all over again. Eventually (after about 500 miles) this self-adjusting process produces the exact A/F ratio needed for proper operation with the headers.

I just wanted to point out that the whole reason for the ECU trying to maintain a 14.7:1 A/F ratio is for emission control. The catalyst works at top efficiency at a very narrow band of A/F and that's the reason for the O2 sensors and all the rest of the gear. Of course we get a few side benefits as well as some headaches out of the deal! I keep a pretty close watch on the "learning" that takes place on my truck and truly believe that it has a mind of it's own! I can't complain too much because it runs strong and gets decent mileage, but sometimes when I really want it to go, Toyota says "uh uh." Other times it leaps away from a green light at an suprising pace! One other thing that I wanted to mention is that the fuel trim is maintained separately for the two banks of the engine. On mine (with headers) the left bank (bank 1) usually runs about -1.5%, while bank 2 runs about +1.5% correction. Also I notice that the long term fuel trim updates while driving, and not just after having turned the engine off. I'd be interested to find out if anyone without headers sees as much difference between fuel trim from side to side as I have. I've heard that fuel trims less than 10% are considered good, while on a late Toyota it really should be less than 5%.

[BE58 Captain]

Dear Mr V8,

I am considering headers and exhaust for my 2000 tundra. You seem to have done the most research, so what is your conclusion on the most gainful setup? I already have the TRD filter?! I am looking for more power, but I dont want the mileage to go down. It already hurts as it is! Any info is greatly appreciated.

Thanks

[My03Tundra]

Originally Posted by BE58 Captain

Dear Mr V8,

I am considering headers and exhaust for my 2000 tundra. You seem to have done the most research, so what is your conclusion on the most gainful setup? I already have the TRD filter?! I am looking for more power, but I dont want the mileage to go down. It already hurts as it is! Any info is greatly appreciated.

Thanks

That, my friend, is the eternal oxymoron.

It is almost impossible to add "more" power without the loss of something, particularly mileage. You can do many things that will make the truck scoot down the road and humiliate most of the ricers out there but you'll definitely experience a loss in mileage.

This is one of the reasons why I've kept my truck predominatly stock. I'd love to add some JBA headers, Spintech XL single outlet muffler in a slightly smaller diameter then stock, a cold air intake system, and Unichip.

[BE58 Captain]

Actually i have done alot of different performance mods on my various tacoma's and yeilded much better performance and fuel economy. Its not impossible. I am asking this question because it seams the tundras are very sensitive to the air intake and exhaust system combo. I dont want to invest in something that will hurt my low end torque or fuel mileage. But if its not possible to get more performance with the same or better mileage then mine will stay stock. Just looking for constructive info.

Thanks

[H2O_MAN]

Originally Posted by KorovaB2

Speaking of which, I've driven about 500 miles and I'm definitely feeling them now. I was surprised most on how tender that gas pedal became. When I put my foot down, I GO!

Just wait until you have a few thousand miles on them.
I think I have about 10K on my JBA's and I can really feel the difference.

BTW, everything else (intake & exhaust) is bone stock. Also,
I'm running tires with a 30.7" overall diameter (stock is 29.6").

[v8Toilet]

Originally Posted by BE58 Captain

Dear Mr V8,

I am considering headers and exhaust for my 2000 tundra. You seem to have done the most research, so what is your conclusion on the most gainful setup? I already have the TRD filter?! I am looking for more power, but I dont want the mileage to go down. It already hurts as it is! Any info is greatly appreciated.

Thanks

I suggest you try the JBA headers or SSautochrome headers if price is a concern. These two will bolt up to your stock exhaust system with no modification. The WOT power differences between them are negligible. I think the JBA headers are a little better in part throttle position situations but I have no dyno proof since all my dyno testing was done at WOT. I do know the JBA headers are quieter. I’ve run both of them on my truck. The TRD headers are good but you have to cut and weld your stock exhaust for those and they are expensive. The S&S headers are not stainless steel so I don't recommend them.

You need to get rid of that TRD air filter and put in a new stock air filter. The stock air filter flows better than a TRD air filter when new. You can modify the stock air box by cutting away some of the tongue on the lower box but this is not necessary. Forget intake systems, I've tried one and saw the dynos and all of them basically do the same thing. You gain top end horsepower in lieu of low end torque and they are very noisy. During track testing my truck consistently had worse 60-foot times than with the stock intake system and I let the computer adjust to the performance intake system for over 1000 miles. I tested them both on the same day. The stock system is better!

Find a good flowing 2.5" single inlet and outlet muffler like Spintech, Magnaflow, Gibson, or other and graft it in place of your stock muffler. If you can find a used stock exhaust system you can do this without cutting your original exhaust and if you decide you want to go back to stock you can. The key is the stock 2-3/8 exhaust pipe! Don’t buy a cat back exhaust system with pipe diameter that is any larger than your stock 2-3/8” pipe. Don’t even try 2-1/2” or you’ll lose some of that off the line torque that makes your truck fun to drive. Stay away from dual exhaust.

The next time you buy tires consult Consumer Reports or ask me and buy a tire that has a low rolling resistance. Consumer Reports says that gas mileage can vary as much as 2-3 mpg from the highest rated tire to the lowest rated tire on the same vehicle. Rolling resistance also effects how much power actually gets to the ground and propels your truck. There are not too many truck tires that have a low rolling resistance so you have to be careful. Michelins are usually rated well there.

If you do these modifications you should get gains in power similar to what I’ve achieved. Your truck will gain low end torque right off idle and make more top end horsepower also. The gas mileage will stay about the same and with the muffler you’ll gain a little more noise. You could try the Unichip but I have no experience with that. From what I’ve read on TS and else ware it’s a worthwhile modification but not necessary and the cost is high.

So JBA headers, higher flowing muffler with stock pipe, stock air filter, and better tires is the formula. Other than a few parts of the exhaust system the engineers at Toyota did a good job of getting a lot of torque from this small V8.

[errn]

I have a 2006 tundra sr5 double cab, want to increas fuel/mpg and power....I seem to get the impression that I need to leave the air filter alone and buy ceramic coated headers with a new muffler and leave the exhaust stock....Is this correct? What headers and exhaust should I go with? Any one else with the same year that went through the changes?? What would "unchipping" do for me and how do I do that....newbie
Thanks
Jim/LA-Katrina land/swamp

[123Gone]

The computer doesn't need a "chip" to make it tunable. My Corvette doesn't have a chip and it definately is tunable. There is an aftermarket program called LS1 Edit that all the tuners have. After I had headers installed, they "tuned" it with the program. They worked on the air/fuel ratio, when the fans come on, etc.

I can't imagine just slapping on mods without a proper tune. The computer may not adjust correctly to your mods. Perhaps someone should contact the company that writes LS1 Edit and see what they can do for Tundras.

[jkib]

Any more input with the JBA's on the vvti engines. Some have installed them, and I'm wondering how there doing now that they have some miles on them.
Thanks