Do I really need the O2 Sensors up front?

[Clyde65]

Hey guys, tell me if I need the O2 Sensors up front. I thought the retune and wiring I paid for would have them removed like the rear ones. The guy that did the harness said it will run alot better and cleaner if it has them. I have a stock 4.8 in an old Chevy truck.

[RedHeartbeat]

Yes, you need them unless you're going to pay someone to do an open loop speed density tune for you.

[Clyde65]

Sorry for my stupidity but what is that monster? Speed Density tune? I had it re configured, is that different?

[oleshifty]

oxygen sensors tell the computer if it is running rich/lean.

if you do not have them, the computer will just pour in extra fuel to stop any kind of detonation/backfire.



A speed density tune uses different sensors to measure load/vaccum, and changes the air/fuel based purely off that. Many guys switch over to this method when adding a turbo because it is more consistent, and doesn't rely on sensors in the air path.



For your application, stick with the front oxygens. They aren't hard to add...weld 2 bungs to headers, or use the stock manifolds.

[RedHeartbeat]

It is simpler to just use the 02 sensors and be happy with it.

OLSD means the PCM is going to control the fuel mixture at all times with no feedback from the oxygen sensor or mass air flow sensor. The OLSD tune is nowhere near as accurate as the live interface you get when using feedback from a good working set of 02 sensors. Changes in humidity and ambient temp will affect the tune. There are many variables that affect a tune and using the 02 sensors helps to compensate for the variances plus you normally end up with much better fuel mileage.

[Clyde65]

I really appreciate your input, I guess now, I am glad the O2 sensores are there. Thanks again.

[skeet]

for you yeah you need o2 sensors lol

me no SD all the way

[CHEVROLADE]

yup use em

[jetmech]

Agreed! I enjoy my 20mpg on the highway while running 14.7 on the wideband......plus or minus 0.1 from time to time