Bigger Exhaust / Less Economy

[Scottie]

Hey guys, bought and fitted a HKS Super Dragger 3 inch exhaust and am getting really average economy.

Last few tanks with my stock exhaust and Ralliart muffler were reaching around 450kms, now i am getting 250 or so.

The guts of the muffler look ok and there is a slight power increase so guess it is all good, but just bad economy.

Any ideas??

 

[godzilla]

Better performance = heavy right foot?

Was your O2 sensor damaged during the change over?

 

[Scottie]

Have booted it but done 3 tanks now, it is drinking heavily. Even had a fellow Legnum ownder comment on it.

Didn't go near the o2, it is a catback.

 

[jet150]

Hey Scottie is it a 3 inch or a 2.5?

Are there any leaks or pin holes in the exhaust.

Is there a chance it's leaking at the flange????

 

[godzilla]

Hey Scottie is it a 3 inch or a 2.5?

Are there any leaks or pin holes in the exhaust.

Is there a chance it's leaking at the flange????

Leaks AFTER the O2 sensor will have nil effect.

 

[VR4Rocket]

Get a tune up....respark the ECU...

 

[Scottie]

It is 2.5 out of the cat and goes to 3 inch after about 8 inches. Exhaust is in top nick. Replaced all gaskets as well.

Even if it was leaking i don't think it would explain the economy i am getting.

 

[Scottie]

Have done 2 ECU resets.

 

[cyber_scriber]

Scottie.

I would suggest that you do a full ECU reset to enable the ECU to "learn" your new state of mods.

Edit - too slow with my response!

 

[VR4Rocket]

Just thinking you are running really rich...can you smell fuel when ideling?

 

[godzilla]

I am sorry Scottie but i have no idea, it makes no sense to me. Freer flowing exhaust should INCREASE fuel efficiency bar what i mentioned about the heavy right foot.

 

[jet150]

Try Steves Kakimoto, I'm sure he'll let you borrow it.

See what happens?

 

[Scottie]

Maybe, want to get this one sorted tho. When Steve is done with my stocker, i will just throw that back on.

Just don't understand how thirsty it is. If it was 50kms per tank less then i wouldn't mind but it is around half. I will try my old o2 sensor and see if that makes any difference.

 

[VR4Rocket]

I noticed that my fuel economy dropped when I put on a new exhaust, hard pipes and airfilter....I combated this with a Interceptor

 

[happymatch]

thats strange as well. When i got my exhaust done, i was heavy footed for first tank but for the second tank, it was about the same. Didi you installed it your self? or the at the shops? thats strange....

 

[snickells]

You want your stock unit back Scott? We can swap if you like?

 

[bradc]

I had increased economy too with a full exhaust system, mine did include downpipes though.

 

[ygoslo]

My guess would be that the ECU has richened the mixtures because it is getting different readings. Remap should fix it, I'd have thought. Have you noticed any difference in performance?

 

[frozen]

mm pretty sure you'd have the 7202 wouldnt you? i'd get a tune might get even better economy than what you started with.

 

[Scottie]

Will have to check ECU, have been lazy, heh, don't even know where it is.

Yeh put it in myself. Performance is OK but not a huge gain.

Steve, all is good. I finally got a job and it is only 10kms away, so just hang on to it for a bit longer..