Maxed Out!

[SB4]

Originally Posted by Grechie

i have a brand new oxy sensor i bought recently from repco (like 3 weeks ago) , dave (SLOWEA) recomended it

Hey grechie, how much did the oxy sensor cost you? I think i need to replace the one on my car aswell.

[Rollin]

If your O2 sensor is working properly the injector size should not matter, as the O2 sensor will detect there is extra fuel getting in and shorten the injector pulse to bring AFR's back to normal, that is the whole reason for having the O2 sensor to control the AFR's

Narrow band 02 sensors as fitted to 99.9% of all fuel injected cars since the dawn of time are exactly that. Narrow Band which means they can only tell the computer if the engine is running "rich" "lean" or "stoich".

"rich" could be anything from 10:1 through to 14.6:1, lean anything from 14.8:1 to 30:1, the car can't tell the difference. The computer is only looking at the 02 sensor at idle or light throttle cruise once the car has warmed up.

They can compensate a small amount for changes in injector size, but the results are a bit haphazard, and considering the car has a decent cam and exhaust already, putting bigger injectors in might 'work' but he would be much better served with a proper tune.

If you are going to get an aftermarket computer then you can go as big as you like - I had 46lb/hr injectors in my turbo car and that still had a stoich idle once tuned.

[Walkinshaw]

Originally Posted by Rollin

"rich" could be anything from 10:1 through to 14.6:1, lean anything from 14.8:1 to 30:1, the car can't tell the difference. The computer is only looking at the 02 sensor at idle or light throttle cruise once the car has warmed up.

Bingo, Narrow band O2 is absolute Junk. Grechie get your hands on a set of 24's from a Magna from you-steal-it (or similar). Failing that if you're going to run a chip etc grab a set of 30lb or even 36lb injectors. I maxed a set of 19;s with a 275kpa reg at 4800rpm so they are pretty much usless above 145-150rwkw

[XRated]

Originally Posted by SB4

Hey grechie, how much did the oxy sensor cost you? I think i need to replace the one on my car aswell.

Sam, I think I paid about $60-80 from Bursons a while ago.

[Thanatos]

Originally Posted by shuresm58

yeh grechie, but dont forget, to do it right you would go AU XR8 Bluetop injectors (24lb) and a unichip of some sought.

Dave (Thanatos) had roughly the same setup as you and managed 175rwkw(?) with a unichip and the bluetop injectors.

It wasn't even close to the same setup, but that's not the point. :P

Your car isn't leaning out THAT much, so putting in injectors that are too big will make it chew through fuel and be a pig to drive down low. I would be willing to bet that with an xr6 fuel reg and blue top injectors it would probably run too rich (thus costing you power as well). The Oxygen Sensor will not be able to compensate for this. As stated earlier it is just a narrow band sensor.
You could perhaps try some standard AU injectors. In an AU these flow the same as an E-Series, but because they are a different impedence when you put them in an e-series they flow slightly more. You could probably get some from the wreckers for next to nothing and it would be a good place to start.

Also, if you want to try and avoid shelling out for a ecu/chip, then you could try an adjustable fuel regulator (such as a malpassi), this will enable you to make fine adjustments and try and find a good compromise between too rich down low and too lean up high. They only cost about $150 too.

Of course the best option overall would be a good chip or ecu. If you do that, then you can pretty much go however big you want in the injector department.

Cheers,
Dave

[Grechie]

thanks, so my first step is to get AU i6 injectors, then if leaning still occurs (shouldnt becuause its not leaning to bad) then ill try magna injectors (24lb)


cheers

- Grechie

[EBIIXR6]

arent blue tops 21 lb and beige tops 24 ?

[old_mate]

hows the idle now grechie? if it idles, im getting this cam

[Grechie]

hunts a little bit, nothing bad