Wide Band not accurate

[foxspy]

Hey guys,

I've had my FAST for almost 3 years and I haven't had time to get out to the track and tune much. I went out to the track last week and did some data logs. At WOT my air/fuel ratio is at 12.5:1. The motor is a 502ci BBC, N/A. I was getting less that 5% correction at WOT, but it was WAY slow. I put it in open loop and started to add fuel one VE # at a time. By adding a toatl of 4#s, going from 74 to 78 VE at WOT, my E.T dropped eight tenths in the 1/4.

What I'm thinking is that my O2 sensor is reading richer than it acutally is. Awhile back I had an Inovative WB unit along w/ the FAST wide bad plugged in and the FAST was reading .8 richer than the Inovative. So my air/fuel ratio was actually around 13.3:1 instead of the 12.5 that the FAST was showing.

Any ideas on how to correct this problem? This is the original sensor I got w/ the computer 3 years ago, about 10k miles.

Any suggestions/tip are greatly appreciated.

 

[V6 Beast]

Why not tune the car to 12.0:1 or 11.8. Everyone says 11.5 is best for a Turbobuick but my car runs best at 11.0.


Sully

 

[10SV6]

Hey Sully, everybody ?

Foxspy, is the O2 sensor in an open header ? Any cracks or exhaust leaks in the headers ? Go over them closely. The O2 sensor placed in one header is an average of the 4 cylinders of that bank. Misfires can throw you lean, cylinder imbalances can mess then sensor up, all sorts of things. As long as the sensor stays consistant, tune for what the motor likes.

I tune on a car that at idle, the O2 sensor reads 15.7:1, but the motor likes the fuel and timing thats there. The sensor isn't reading right, so I turned the correction off at idle. Afer the rev's come up the sensor comes back in line.

You know the motor likes to run richer than 12.5, so tune it richer than 12.5.

 

[foxspy]

There might have been a slight exhaust leak, but it's fixed now and I'm going to the track tonight to do some more testing.

Thanks.

 

[norbs]

When you did the wideband tests, there was no other changes made?

 

[Lonnie]

If the o2 correction was close, you should have changed the A/F table to richen the mixture, not the VE table.

Give the motor what it wants to run well, not what value you think it wants. If the o2 is off, & you have to set it to 11.8 instead of 12.5 to compensate for the o2 error, then do it.

Just read the plugs, measure the EGT & watch for detonation to prevent engine damage.

 

[foxspy]

But why was my wide band reading almost a full point off from another wide band, running at the same time?

I am tuning my wide band out to where it's running the best, but I think I'm getting "false" readings. How many N/A motors have you seen the best w/ 11.3:1 air/fuel ratio?

 

[norbs]

Thats a very good question, only way to get an answer is to use your fast o2 connected to your separate wide band unit, and see if that unit reads different than thae fast software. I heard the innovate controller will work on any o2 sensor. Where are your wires running for the wb band, close to spark plugs, or next to any high current wires? I am working on shielding the o2 wire harness, i feel it is pickiing up wrong signals myself sometimes, and i can't explain it