Engine masters : A Study in O2 Sensors and AFR Readings

[Nashville Cat]

Engine Masters
S8 E20 • A Study in O2 Sensors and AFR Readings

You have to have motortrendTV to watch this, but here are some highlights :

They tested 5 different AFR gauge setups from Innovate, AEM, Autometer and IDK. They all read within 1/2 point of each other.
AEM tended to be the leanest while Autometer was about 1/2 point richer.
If you have a bad misfire , it will not read rich, it will read lean ( a high number) because the sensor is reading oxygen levels, not fuel.
The ideal placement for the sensor is 6" to 12" after the 4 tubes come together.
If you have an exhaust cutout, the cutout should be 18" to 24" downstream from the sensor. If the cutout is too close, the sensor won't read correctly until high rpm.

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tv.youtube.com

 

[Shovelrick]

Engine Masters
S8 E20 • A Study in O2 Sensors and AFR Readings

You have to have motortrendTV to watch this, but here are some highlights :

They tested 5 different AFR gauge setups from Innovate, AEM, Autometer and IDK. They all read within 1/2 point of each other.
AEM tended to be the leanest while Autometer was about 1/2 point richer.
If you have a bad misfire , it will not read rich, it will read lean ( a high number) because the sensor is reading oxygen levels, not fuel.
The ideal placement for the sensor is 6" to 12" after the 4 tubes come together.
If you have an exhaust cutout, the cutout should be 18" to 24" downstream from the sensor. If the cutout is too close, the sensor won't read correctly until high rpm.

Watch Engine Masters online | YouTube TV (Free Trial)

Start a Free Trial to watch Engine Masters on YouTube TV (and cancel anytime). Stream live TV from ABC, CBS, FOX, NBC, ESPN & popular cable networks. Cloud DVR with no storage limits. 6 accounts per household included.

tv.youtube.com

Figures, my exhaust system is SS and I’d need to buy some type of 3” pipe with a bung or 2 pipes and leave the screw in plugs in the bungs I just welded in

 

[Nashville Cat]

Figures, my exhaust system is SS and I’d need to buy some type of 3” pipe with a bung or 2 pipes and leave the screw in plugs in the bungs I just welded in

I thought you welded your bungs in at the collector flange ? That should be perfect ?
Should look something like this :

 

[Shovelrick]

I thought you welded your bungs in at the collector flange ? That should be perfect ?

It’s only a few inches away from the 4 tube intersection, the info said it needs to be farther downstream Edit I think I’m good

 

[Molly's 70]

I think your good to go.

 

[Derek69SS]

If you have a bad misfire , it will not read rich, it will read lean ( a high number) because the sensor is reading oxygen levels, not fuel.

If you have an exhaust cutout, the cutout should be 18" to 24" downstream from the sensor. If the cutout is too close, the sensor won't read correctly until high rpm.

I killed an engine from these 2 things with some temporary short pipes to make my car driveable before I finished the exhaust.

read lean at idle with too short of pipes.. computer compensated by dumping in more fuel.
more fuel fouled out plugs, which made it read leaner yet, so it dumped in more and more fuel.

Then I fixed it, and didn't realize I had so much fuel in my oil, and wiped the bearings out.

 

[Nashville Cat]

That looks like 8 inches to me. Perfect.

 

[Shovelrick]

I killed an engine from these 2 things with some temporary short pipes to make my car driveable before I finished the exhaust.

read lean at idle with too short of pipes.. computer compensated by dumping in more fuel.
more fuel fouled out plugs, which made it read leaner yet, so it dumped in more and more fuel.

Then I fixed it, and didn't realize I had so much fuel in my oil, and wiped the bearings out.

The O2 sensor doesn’t control anything on mine just an A/F gauge, I’ve always been on the can’t Hurt anything if you’re Rich but Lean can destroy an engine, but I’m trying to get the Eye Burn gone

 

[Nashville Cat]

Frieberger mentioned that you could lean down the idle and cruise as long as the power valve comes in early.
That's what I plan to do. I've noticed some 850's are jetted square (80-82 jets in all 4 corners)
while some are jetted 70 in the primaries and 80 in the secondaries.
I will start with 72-78 front - rear and a 8.5 power valve to come in early. Also front nozzle of .028 and rear .031.