Hi guys, it seems that I lost gas mileage after I installed Longtubes and ory in my car (I haven't got a basic tune yet but I will end of Dec). Its been almost 2 weeks now since the install. On a full tank I usually get around 250-270 but this time I got only 200 miles on the tank. I don't think I drove it hard enough to be losing that much gas. I've been keeping and eye out on the gas and already in 2 days driving 30miles it seems that I've lost about 2 gallons.

I've done my search here and some say I will be losing mileage for the next few tanks of gas. Maybe because I haven't gotten a tune yet (but most done even get a tune after longtube install). I have no idea whats going on guys. Please help me out so I can solve this mystery asap.

NOTE: I have Flowtech LT's with 3" ory with no cats with 3" ipipe to muffler.

 

A good tune will give u better gas mileage even when the car is stock. Generally, cars leave the factory running a tad rich. So anytime u add a significant mod, u will want a tune to redial in your a/f ratio. After a good tune, u will most likely see an improvement. Usually when people add headers and dont get a tune, its usually cuz they plan on doing a cam or some other big mod in the near future, so considering the mpg loss and driveability issues wont be drastic til then, they usually wait til the cam goes in (or whatever else thay may want to do in the future) I know thats what I did. I waited til i installed my heads and cam before i tuned it so it could all be done at once. Sometimes its good to tune after each mod, just so u can put the car on a dyno and see how much each mod has added.

 

Man I remember when my car used to get 270ish to a tank. Those days are long gone.

 

I got 240 or so before headers and then went to 180 or so...got a vinci tuner and am now back to 220-250. Yours needs some sort of a tune...Bosch 13111 02 sensors help..

 

Thanks for the help guys. I'm really hoping a basic tune will fix all this drama for me. I dont plan on doing heads and a cam anytime soon cause I have other priorities right now. But I sure would love heads and a cam. I'm planning on getting a tune end of Dec when I get some Christmas money woohoo. I'm getting a tune for $200, not a full tune cause I was told thats not needed for just a LT install.

I'll need to do research on a vinci tuner or Bosch, I have no idea what those are hahaha. Thanks guys!

 

I just recently had LT/catted Y installed, plus tune. I dont drive my car daily, but Ive noticed a loss in gas mileage. Probably due to a heavier right foot

 

Thos Bosch O2 sensors are the Corvette (longer) O2s and would be great to replace those ghetto O2's I wired up with the Pacesetter extension kit. In the long run they may be easier and cheaper then getting extentions for the remaing rear O2s you have left.

Each car has its own characteristics, like we discussed; a tune will fix you up proper though.

 

270. damn son. Im lucky if i get 210 220. maybe i just have a heave foot but im usually pretty easy on it

 

So with your SES tuned out you wont need these right?

 

yes he will, those are for the front. when u get headers your front 02 sensor location is moved back so u either need extensions so your 02 sensors can reach the connector, or u just buy the 02 sensors with the longer wires.

 

After a good tune, and with 4.10s, on long distance trips I typically get 400+/- mpg to a tank on the highway cruising above 75mph. City driving is a whole other animal!

 

What everyone else said, get a tune and you'll be happy. Hell I get 200miles per tank in my H/C/E car with 4.10's.

 

Okay guys now I seem to have another problem. I went to my friends house today to let him hear my setup. After revving my car up I started to hear some kind of sound. My friend said it may be an exhaust leak cause thats how his car sounds like. But when I took up from his house to go to work there wasn't that sound. It sounded like a clicking sound or something. I got to work and listened for it, even popped my hood and there was no sound.

Now when I got home tonight after I parked there was the sound again. I examined where the sound was coming from and it seemed to be around my ypipe. I thought it was just my ypipe hitting against my floorboard but I did the heater hose mod so it shouldn't be that. What was weird was while I was hearing that clicking or ticking sound I was getting small popping sound coming from my exhaust (Azrael I forgot to mention this to you in the PM). Hmmmm what the hell is wrong? If it was a leak then it would constantly be there right? It wouldn't just be there and just go away and come back later right?

 

I gained mpg because I had a fucked up cat on the passenger side. lol

 

i didnt really see any difference because i still cant keep my foot off the pedal since it sounds so good now that i have the headers (vs just a reg catback)

 

Hey bro I sent you a PM on Norcal. When do you hear the popping sound? if it is on decelleration through the exhaust it is just the exhaust backpressure, if it is any other time let me know. If you get too disturbed by it I will drop by and give it a listen next week.

 

Raise answered your question. Thanks Raise!

Tuning out only deletes the codes for the rear O2s, you still need front O2s with either extensions or the longer Corvette style O2s to reach the relocated O2 bungs.

 

I had a problem like that. It sounded like an exhaust leak when i fired up the car and then it would go away after the car warmed up. It ended up getting worse as time went on and it was a leak so I would get it checked and be sure everything was tightened properly.

 

No problem man

 

Nice car.