Huskymaniac

Just purchased a 2005 TL with a 6 speed manual. I'm not sure I really wanted a manual but I wanted a limited slip differential.

One thing I would love is to improve the gas mileage. The car has plenty of power and torque for my daily driver purposes and I am generally very easy on my cars. My commute is at least 2/3 highway.

One thing I have read is that bringing the torque peak down as close to cruising RPMs as possible helps highway mileage. So, in a sense, one way to help MPGs might be to sacrifice peak HP by sacrificing HP at high RPMS to get more HP at low RPMs and, in doing so, shifting the torque curve toward low RPMs.

I have done some searching on the site and it seems like possible mods for this goal might be:

1. Headers
2. J-pipe
3. Pre-cat delete
4. Underdrive pulley

I have to admit that I don't get the pulley at all. Maybe someone can direct me to a good link with an explanation on how it works. Are the headers and J-pipe compatible? Are they redundant? Will pre-cat delete cause a CEL? If so, that is out for me as I am in NY and we can't have a CEL on when we do our annual inspection. I understand that a CAI typically hurts low end torque and will probably hurt MPGs. Is that a correct assumption?

Huskymaniac

Oh, and I forgot:

1. Throttle body spacer
2. Intake manifold spacer

Both of them seemed to be used for shifting power to the low end.

TLtrigirl

iTrader: (1)

headers....i do not believe you can do anything with these on the TL.

J-pipe...search there is a lot of info out there.

PCD....will cause CEL. if you get a j pipe with 3rd cat delete you will not get a CEL (no sensor).

pulley...i've seen threads on this, but someone else with better insight may be able to help you out with this one.

CAI...i have one...i dont' think there really is a noticeable difference with MPGs or low end torque. most people will say it's an overpriced noise maker at WOT with little gains unless you plan of freeing up the rest of the exhaust.

if you want MPGs....the TL is pretty efficient on it's own for a V6. don't pedal mash and you should be fine. usually with all those mods listed, people want more power to go faster. it's not so much to improve MPGs.

justnspace

iTrader: (1)

unfortunately, the mods to our cars shift the power band UP!
our cams have two different profiles and it switches at about 4700RPM. so, yep, you guessed it...peak power is made up top!!!
with that being said, you will never lose torque.
in fact, you will gain torque at lower RPMs with those mods.

and in theory; making the exhaust as free flowing as possible will net MPG gains, but only slightly.
as TLtrigirl stated the TL's engine is efficient enough without the mods.

here's a tip. Always keep her in gear when decelerating. The fuel injectors are shut off!!!! which means no gas is being used. if slowing down and in neutral, the injectors are still flowing!

justnspace

iTrader: (1)

oh and throttle body spacers dont do jack. dont waste your money

justnspace

iTrader: (1)

how a light weight pulley works - Reducing rotational mass is always a reliable way to gain a few ponies on nearly any engine.

TLtrigirl

iTrader: (1)

justn's on a roll...

Huskymaniac

OK, let me see if I can summarize what I think was said:

1. There is no header mod for this car
2. J-Pipe will help a little
3. J-Pipe with 3rd cat delete will help a little more and should not cause a CEL. Does this car not have 3 O2 sensors? My SVX with two pre-cats and a3rd cat has three O2 sensors. And does one need to install bigger precats if the 3rd cat is deleted?
4. Precat delete is out due to CEL
5. Underdrive pulley will increase available power and torque due to reduced rotational mass. This will be benefical, I believe, to city driving since changing speeds causes one to lose, and have to re-supply, rotational and linear energy. But I don't think this will help with highway MPGs. Does a reduced rotational mass pulley make the car easier to stall for a newbie stick driver? I will have two of them in the house.
6. TB spacer doesn't help at all
7. No opinions, so far, on intake spacers.

TLtrigirl

iTrader: (1)

there are 3 cats....the 3rd cat has no sensor. the pre cats do, hence CEL. you can either go with a type-s precat (which has a less restriction than the base precats), or HFPC that will not throw a CEL (i think).

jpipe is known as the biggest bang for your buck mod for the TL. then the PCDs in terms of power gains. all the other mods basically will help. intake spacers based on what i have read...might yield 1-2 HP but you won't feel any real gains.

justnspace

iTrader: (1)

we dont have a need for headers because our heads are cast into the block.
coming right off the block is the two primary cats. which we replace these 'cats' with 'straight pipes' called Pre-cat deletes.

intake manifold spacer in theory could work.

Huskymaniac

How many O2 sensors does this car have? I have seen reference to upstream and downstream. Are there two before the precats (one on each side) and two after?

justnspace

iTrader: (1)

the car has 4 o2 sensors
2 on the front bank of the catalytic converter coming off the heads
2 on the rear bank of the catalytic converter coming off the heads.

the third cat underneath the car does not have a sensor.

Scottwax

Best way to maximize fuel economy is to not romp on the car as much. You start modding the car, you'll be taking advantage of the extra power and use more gas, even though in theory, mods that improve midrange performance like the J-pipe and spacers, should improve mileage.

vietxquangstah

iTrader: (7)

PRECAT DELETES DO NOT, I REPEAT, DO NOT CAUSE A CHECK ENGINE LIGHT.

I have had rv6 v3 precat deletes installed for well over 1 year and not a single check engine light. No codes pending.

Precat deletes come with defoulers installed so you can still plug in your factory o2 sensors to it (up and down streams) due to the angle they are plugged in, the computer sees everything is ok and DOES NOT trigger a check engine light.....

AccordFlex

iTrader: (1)

Yea ive never got a CEL with my PCDs.

justnspace

iTrader: (1)

^i had a quiet CEL for the longest time.
it would not show up in the car, but as soon you would hook up an OBDII reader, it would throw the code.

one day, my Rear PCD cracked due to my lack of blipping the throttle hard enough for a downshift.
I replaced the PCD with a new one and I guess I positioned the defouler and o2 sensor correctly this time around.

NO CEL!!

JJH

iTrader: (1)

Did not know this, I always shift to neutral when I'm coming to a stop because

1) I don't know how to rev match my downshifts
2) I thought that taking the stress off the clutch/tranny/engine would be good for it, and I'd rather replace brakes than damage any of the above.



I'm one of the few unlucky ones that DOES get a CEL for my PCDs. I might have swapped my two upper O2 sensors since they look the same, but I figured they were the same anyways so that's probably not the issue at hand.

justnspace

iTrader: (1)

with enough practice and time you'll get the downshifts.
however; when coming to a stop, I always just leave it in the gear i am in, no need to downshift. the RPMs come down to like 900-1000 but it never lugs. and then as the engine is nearing to lug, I depress the clutch and brake.

plus, if left in gear, you'll have immediate power in case you need to do a emergency maneuver. no need to fumble with gear selector

Huskymaniac

That is interesting. Now here is another question on this subject. If any of the cats are deleted, are you technically breaking emission laws? I guess I would deal with lower MPGs if it meant not technically breaking any laws. Perhaps precats or the third cat can be deleted if the other is replaced with a more effective unit.

TLtrigirl

iTrader: (1)

^^yes technically tampering with any of the cats or mods to the exhaust system is illegal.

vietxquangstah

iTrader: (7)

it's a federal crime to tamper with any emission related components on the car unless you are replacing it with another unit of the same. In cases like deleting them is a big no-no. We still do it anyways lol.

Nick216

Fuck da popo.

klene259

welcome!

Huskymaniac

Thanks all. I looked at the XLR8's dyno results for the j-pipe. First, they only provide data on the one that deletes the 3rd cat. And then it only gives you about 12-20HP, depending on the RPMs. The good news is that it gives the biggest gains at low RPMs. But the numbers would suggest, based on other stuff I have read, that the majority of the gains came from the cat delete and nearly nothing came from the j-pipe. To stay legal, and pass emissions in every state, I would think that the most aggressive thing one could do is replace the pre-cats with the type-s pre-cats and replace the 4rd cat with an equally slightly better flowing 3rd cat. But that will probably only gain about 12HP overall. And the cost would be three new cats, which is pretty high. Not sure if it is worth it. Maybe when/if the cats need to be replaced it would make sense to replace them with slightly better flowing ones.

A question for the board members. And don't take this as inflammatory, but, which acura forum on the web has people who are more mechanically knowledgeable from a diagnostic standpoint? I am more concerned about learning how to care for the car than I am on how to rice it up bro-dawg style. I don't want a loud exhaust with a fart pipe on it or any extra plastic or glowing bits. I want to know how to fix "X" when it breaks.

Huskymaniac

I meant 3rd cat, not 4rd cat.

justnspace

iTrader: (1)

well, you didnt really ask a question, as we are here to help you with anything that breaks.
so, what broke?

as said in the first couple of post by TLtrigirl and myself, the engine is pretty efficient by itself without any modding bro-dawg style.

JJH

iTrader: (1)

You're not going to find a better community of TL owners. I'm not interested in ricing out my TL bro dog style.

Huskymaniac

Understood. It was an aside question on forums. I guess I was assuming one forum had lots of people interested in modding their car "bro-dawg style" and another would have more of the engineering/mechanic types who are good at diagnosing problems.

TLtrigirl

iTrader: (1)

if things break people post in "problems and fixes" under the 3G TL sub section. however if you do enough searching, more than likely someone else has already posted a similar issue with plenty of responses from folks that had it fixed or know how to fix it. the 3G TL has been out for 9 yrs...

most 3G TL owners aren't here to excessively accessorize their cars in a manner where it going to overly polarizing. then again, it's your car, you may do what you wish.

other DIYs for "fixing" your car may be found in the 3G "garage" on the general 3G TL forum page. it has been stickied by our moderators for your convenience. there is a ton of info out there. keep in mind that some of the "problems" may not necessarily be model specific, since they may occur in the other models as well (like, "i get a clicking noise when i turn." which usually means it's more than likely an inner CV joint/axle issue).