LS1 Fuel economy or lack of it.

[RicheCV8]

So in the last 3 weeks I have noticed a rather sharp decrease in my fuel economy. 450 km's a tank is average. Driving to and from work and little trips here and there is average but since I had the full exhaust system installed it has gotten really bad.

Was amazing at first, after 2-3 weeks was pushing 500 a tank which is great, now it's at about 360 to 380 clicks and my driving style hasn't changed. So last night I filled it to the brim and have done so for the last 3 weeks. From full to 3/4 is now getting 36 kilometers. Thats pretty bad since 3 weeks ago it was about 80 clicks in the same measurement.

I know it's not the best way to measure fuel usage but it really grabbed my attention.

Any thoughts?

[Ozzie]

Why complain?

If you want fuel economy then why buy a V8 and have an exhaust fitted?

My advice if you want fuel economy is....

buy a corola

[wortus]

Did they do extractors as well? Check to see if they have damaged your O2 sensors in any way and check the colour of your spark plugs. Your not meant to use any thread sealant that can contaminate the sensors either so check if thay have used any and ask them what type and check yourself it is OK to use.

[RicheCV8]

Why complain?

If you want fuel economy then why buy a V8 and have an exhaust fitted?

My advice if you want fuel economy is....

buy a corola

Did they do extractors as well? Check to see if they have damaged your O2 sensors in any way and check the colour of your spark plugs. Your not meant to use any thread sealant that can contaminate the sensors either so check if thay have used any and ask them what type and check yourself it is OK to use.

They did need to move the O2 sensors as the Pacemaker headers sensor mounts are further back so they were extended with adaptors.

As for V8 power, there must be a standard of economy. Even with a corolla there is a standard fuel usage. This car has had no remapping and has started to chew fuel faster than any other V8's with the same mod that I have seen.

[greenfoam]

Things change when you install headers, you can easily loose alot of low eng torque compared to the factory headers and that will cost you fuel economy

[GM GEN3]

i would say O2 sensors are stuffed they tend to do that once headers go one they will need to be replaced ive got headers and full exhuast on my vx ss i only get about 350-400 kms from full tank.

[Bravotwozero]

Why complain?

If you want fuel economy then why buy a V8 and have an exhaust fitted?

My advice if you want fuel economy is....

buy a corola

What a helpful post

To the OP your fuel usage shouldn't change just from fitting exhaust and headers. I'd also say your O2 sensors probably need replacing.

[kane88]

Ozzie is right, even if he's not being helpful. Don't buy an 8 and start bolting go-faster bits on if you're gonna bitch about fuel economy.
OP, as most have pointed out, replace the O2 sensors and work up from there.

[Vt_vic]

did you get tri y extractors???

[Ozzie]

First sign of fuel waste is that it is running rich.

Obviously there would be some slight difference at idle like shaking or idling rough.

Second sign is that it wants more air.
I know CV8's have an OTR intake but have you considered modding it to allow for the extra exhaust flow?

As for the O2 sensors... They either work or they dont. You obviously have the money so take it to Holden and have the car put on the tech2. Might be a completely different problem altogether.

[delcowizzid]

As for the O2 sensors... They either work or they dont. You obviously have the money so take it to Holden and have the car put on the tech2. Might be a completely different problem altogether.

O2 sensors will gradually get worse and worse and lie to the ecu they wont throw codes until they are way out of range or die all together

[colgf]

Something fishy is going on , it cannot be O2 sensors to make such a dramatic increase in fuel consumption, even if all sensors arent functioning the ECU approximates a 14:1 air/fuel ratio the Supposed "ideal" ratio for a 4 stroke petrol engine combustion. My guess is your exhaust fitters have disturbed the airbox & inlet plumbing or MAF sensor or there's an inlet manifold air leak somewhere. Also check your underbody for fuel line leaks, the fitters may have damaged the fuel filter or lines, check your fuel cap fits tight. Check the lines to the charcoal cannister under the rear of the car. If all else fails to find anything get Holden to do a test & tune. Cant possibly be O2 sensors or adding a free flow exhaust.

[RicheCV8]

Well I took it to my autoelec, code issue galore, was in "SAFE" mod so was drinking like no tomorrow. Reset the codes and checked the O2 censors, all was fine. Reset the trip computer, you know the 8 second hold. Gave it about half a tank of 98 and this seems to have fixed the issue but I need to keep an eye on it, am looking at a MAFless tune and an OTR.

[Nanos]

i wish i got those sort of kms. ill get around 300-350km out of tank and maybe 400-450 on the highway. i dont care about it though. it goes well and it is a v8.

if i want economy i drive the combo.

[VTPREDATOR]

Well I took it to my autoelec, code issue galore, was in "SAFE" mod so was drinking like no tomorrow. Reset the codes and checked the O2 censors, all was fine. Reset the trip computer, you know the 8 second hold. Gave it about half a tank of 98 and this seems to have fixed the issue but I need to keep an eye on it, am looking at a MAFless tune and an OTR.

wah wah wah bout fuel and you are looking at a mafless tune and otr. that wont make things economic trust me.

[Bravotwozero]

Ozzie is right, even if he's not being helpful. Don't buy an 8 and start bolting go-faster bits on if you're gonna bitch about fuel economy.
OP, as most have pointed out, replace the O2 sensors and work up from there.

No he isn't. It is common to get an LSX to 240rwkw+ with bolt-ons without affecting fuel economy. Some guys have done cam swaps without any noticeable difference in fuel economy. If it is tuned right that is. Simply saying that people with 8 shouldn't complain about fuel economy is ridiculous. Clearly Riche had a problem but according to yourself and Ozzie, he should simply ignore it. Hell he's got a V8 so shouldn't worry about fuel economy.

[Nanos]

i can tell you now once i started adding on the bolt ons fuel economy changed, nothing bad but it did change. once i did diff gears then it got to where it is now.

you can not mod a car thinking you will get good fuel economy. agreed if i drove my ls1 nice it would return some economy, but why have a v8 if you are going to drive it like a camry.

i enjoy my ls1 so i dont worry about economy. yes it would be nice for it to be little better but im not going to waste money and time to chase 1 or 2 litres /100km when i could be doing other stuff to the car.

[Bravotwozero]

i can tell you now once i started adding on the bolt ons fuel economy changed, nothing bad but it did change. once i did diff gears then it got to where it is now.

you can not mod a car thinking you will get good fuel economy. agreed if i drove my ls1 nice it would return some economy, but why have a v8 if you are going to drive it like a camry.

i enjoy my ls1 so i dont worry about economy. yes it would be nice for it to be little better but im not going to waste money and time to chase 1 or 2 litres /100km when i could be doing other stuff to the car.

Good economy? Define good economy. Good economy for a V8 or good economy compared to a 4 cylinder? No V8 is going to stack up to a 4 cylinder or a big six regardless of what some might say. If Riche posted he was getting crap mileage compared to his mum's Camry then he'd deserve everything he got. But imo Riche is/was getting bad economy compared to other
V8's. I don't care about economy that much either but if I was in Riche's postion I would.

[CANYONERO]

wah wah wah bout fuel and you are looking at a mafless tune and otr. that wont make things economic trust me.

umm..... i had a tune and OTR done and my fuel econ improved by about 2lt per hundred.

[JD]

Good economy? Define good economy. Good economy for a V8 or good economy compared to a 4 cylinder? No V8 is going to stack up to a 4 cylinder or a big six regardless of what some might say. If Riche posted he was getting crap mileage compared to his mum's Camry then he'd deserve everything he got. But imo Riche is/was getting bad economy compared to other
V8's. I don't care about economy that much either but if I was in Riche's postion I would.

Good Economy: When your V8 does 700k's to a 78L tank and your 4 banger does 250k's to a 50L tank!

[RicheCV8]

umm..... i had a tune and OTR done and my fuel econ improved by about 2lt per hundred.

Thats what I thought, seems to be better but I fear the O2 censors may be acting up.

[soop]

Yeah... some people need to keep their opionions them self. Be constructive or nick off.

A sharp increase is almost always indicative of a problem somewhere.
Check of exhaust leaks/blockages and the o2 sensors. After that i'd be looking at the intake and ignition side of things.