Afr gauge

[Aron Gleason]

Before I tore into the 440 to replace the cam and lifters and timing chain my autometer afr gauge worked the way it should. After I got the motor back together the afr gauge will stay at 14.7 once it's done it's normal countdown, everything is hooked up the same as before. I thought the sensor might be bad so I replaced it. But it will do it's countdown then go to 14.7 and it won't move from there even if I rev up the motor. What could cause that?

 

[Geoff 2]

Gauge or sensor....

 

[Kern Dog]

Ha...I've had similar readings as you.
My 440/495 runs clean and the exhaust smells normal but I too suspect that my gauge does not always read correctly anymore. I used to see wild swings between cold idle, warm idle, idle to part throttle and idle to WOT. Now, the numbers still move around a bit but they move in a much narrower range since the engine rebuild in 2022.
Coincidence?

 

[Budnicks]

What brand ? some really crappy stuff out there "now" too

Maybe try an analog gauge, reg full sweep needle
& see if it does the same thing as the digital numerical sh-t

I had the same sort of style problem,
I bought a Autometer Analog full sweep style
in conjunction with a digital/style on the other side of the
exhaust extensions, like 5"s past the collector flanges,
it/the analog full sweep style gauge do a better job,
not bouncing around as much...
It seemed closer to reality too... smell/sniff tester

not sure if you need a closed or open loop style

I don't have that car anymore, sold it a long time ago now
or I'd photo it for ya'

 

[Aron Gleason]

What brand ? some really crappy stuff out there "now" too

Maybe try an analog gauge, reg full sweep needle
& see if it does the same thing as the digital numerical sh-t

I had the same sort of style problem,
I bought a Autometer Analog full sweep style
in conjunction with a digital/style on the other side of the
exhaust extensions, like 5"s past the collector flanges,
it/the analog full sweep style gauge do a better job,
not bouncing around as much...
It seemed closer to reality too... smell/sniff tester

not sure if you need a closed or open loop style

I don't have that car anymore, sold it a long time ago now
or I'd photo it for ya'

Mine is the analog autometer 3379 afr gauge.

 

[Budnicks]

Mine is the analog autometer 3379 afr gauge.

that rules that out, figured I'd throw it out there

I wonder if the O2 sensors are NOT compatible ?

sorry not much help

 

[Aron Gleason]

I bought a Bosch sensor that crosses over from the one autometer uses on their gauge. The previous one was on there for a couple years. It's just strange how it doesn't fluctuate after the new cam and lifters were put in. No vacuum leaks.

 

[Aron Gleason]

Does it sound right that more overlap would cause the afr gauge to be steady at 14.7 at idle and cruise which could be leaner than what its actually running at?

 

[Aron Gleason]

So today I took the car out for a cruise, and it didn't matter if I was idling, cruising or getting on it hard. The afr gauge still stayed at 14.7. And with the new cam and lifters, I can now stab the throttle and no more stumble.

 

[Kern Dog]

The gauge or oxygen sensor are defective. The AFR moves around like a Geiger counter during regular engine operation.

 

[Rebelrouser]

Before I tore into the 440 to replace the cam and lifters and timing chain my autometer afr gauge worked the way it should. After I got the motor back together the afr gauge will stay at 14.7 once it's done it's normal countdown, everything is hooked up the same as before. I thought the sensor might be bad so I replaced it. But it will do it's countdown then go to 14.7 and it won't move from there even if I rev up the motor. What could cause that?

With the engine running simply give it a shot of carb cleaner, don't kill the engine, the gage should spike rich briefly if working correctly. any exhaust leaks that let in fresh air before the gauge will mess the readings up.

 

[Aron Gleason]

With the engine running simply give it a shot of carb cleaner, don't kill the engine, the gage should spike rich briefly if working correctly. any exhaust leaks that let in fresh air before the gauge will mess the readings up.

Shoot carburetor cleaner in the carburetor?

 

[Kern Dog]

Yes.
You will artificially inject a richer mixture to the engine which will register a change to a property operating gauge. The numbers would go lower.