A Very Silly Question, Again: Do The Exhaust Gases Mix in Mufflers?

[Pawel66]

Do the exhaust gases from cylinders 1-3 and 4-6 mix in the mufflers?

I always thought they do. But I had CO reading today 3.2 in the right hand side pipe and 3.7 in the left one. The colour of the spark plugs from 5 and 6 suggest richer mixture than in the other cylinders and so does the CO reading. But again - I thought the fumes get mixed up in two mufflers...

[seeMIL]

Good question. I also had similar experience and would like answers.

[Pawel66]

I am pretty certain now they mix only partially. I do have a different CO reading in the left hand side pipe and the right hand side pipe. This difference corresponds to the difference in colour of the spark plugs in two cylinders.

[stickandrudderman]

Original downpipes have interconnection between them whereas aftermarket often do not. It's possible that this might have an effect but I don't know for certain. In the 40 years I've been doing these cars I've never thought to swap the sample from one pipe to another!

[Pawel66]

I have the original pipe with the interconnections. I am not sure if the passages between the pipes are clear or stuck with sooth though... In any case I would not think these interconnections allow the fumes to mix a lot.

Where I thought the mixing can happen were the mufflers. I do not know how they are built inside.

I do not suppose you would get different CO readings when everything is within specs, certainly. But then if something irregular goes in cylinder 1-3 or 4-6, well, I have different reading now.

[Shvegel]

Stuff a sock in one tailpipe.  If it runs with one tailpipe plugged they mix.

[Pawel66]

I've got holes there, will not work...
  

[garymand]

I took one out and cut it down the joint between the two pipes.  Each little tunnel was plugged with carbon soot or rust.  And, did you get your caster issue resolved?

[MikeSimon]

The two pipes that go into the main, front muffler, end in there and two different pipes exit it. The same is the case in the rear muffler. The pipes inside the mufflers have holes in them. There should be a total mix of gases.

[Alex D]

While on the topic, something of possible interest.  O2 wide band sensor that can check air/fuel ratio and monitor by cell phone.  Something i am considering. 

https://www.plxdevices.com/PLX-Wideband-O2-Air-Fuel-Ratio-Sensor-Modules-Gauges-s/125.htm

[Pawel66]

I took one out and cut it down the joint between the two pipes.  Each little tunnel was plugged with carbon soot or rust.  And, did you get your caster issue resolved?

Working on it.  I bought new. Bushings with proper offset and found inexpensive 243mm leaf springs. i will take it all to the shop, replace, clean up the upper kingpin pivot screws mess I have there and will see.

[Pawel66]

The two pipes that go into the main, front muffler, end in there and two different pipes exit it. The same is the case in the rear muffler. The pipes inside the mufflers have holes in them. There should be a total mix of gases.

Perhaps partial only. I do have different readings in two pipes that confirm spark plug colors...

[Shvegel]

Alex, You will need 2 sensors.  Front and rear bank.