Exhaust gas analyzer questions for tuning a QV

Excellent questions, I've been wondering the same! Especially with respect to your #3, I was looking at the Innovate Motorsports Wideband Air/Fuel Ratio Tuning site.

I think the Innovate LM-2 is the portable solution - where should the O2 sensor go? Is the clamp with the sensor inserted in the exhaust outlet sufficient for accurate measurement? Would you want the dual sensor version? Any need to measure each bank separately?

 

I am presently in the middle of sorting out a significant AFR difference between banks - so the answer is yes to each bank!

 

The only way to test each bank separately would be to use the sniffer tubes in the car which also happen upstream of the cat. You will have a tough time getting the LM-1 O2 sensor to work in that scenario without fabricating a custom set up.

 

Not if it's an '83 308
Banks don't merge until rear muffler
My two test pipes have bungs so I can place an O2 sensor in each output

 

Curious about that. With the CIS system feeding through a single point and a common plenum, all cylinders theoretically should be getting the same amount of fuel. The only way I see this imbalance happening is a bad injector(s) or poor cam timing. If it something different I would like to know.

 

I'll let you know when I know.

I can tell you plenty of things that it isn't and one of those is injectors.
Tested them for spray pattern and pressure threshold on the bench.
Swapped front and rear injectors - no difference in AFR imbalance.

I've checked electrical timing, CAM timing, replaced plug extenders, new wires, went with iridium plugs, checked compression, checked disty caps and rotors. I suppose one ignition coil could be weak - I'll could try swapping them.

I'm not sure about the CIS single point comment - I don't know how each of the 8 outputs are jetted - got to be a pretty small jet.

One more test before I call Larry Fletcher - letting 8 injectors pee into 8 cups tonight

 

When did they stop putting individual test tubes on the exhaust manifold? If those are present you could build a test chamber to hook your wide band to and test each cylinder individually. I'm planning on doing that once I get my test tubes repaired.

 

My tubes disintegrated and I did not replace. It's one of those things that once in a great while you wish you had back.
Well my "pee in the cup" experiment showed #7 output of the fuel distributor about 7% above the others - swapped it with another tube/injector and it stayed at the same distributor output. I don't really trust my coarse measurements so I called Larry Fletcher and I am sending parts to him for a look.

I'll let you know if he finds anything or whether it's a problem with my mechanic - me.

 

Sorry to hear about your troubles.

Was that enough to make it run rough or are you just trying to get it perfect?

 

Hi Brian
I actually think that there are two outputs to the front bank running rich but I am going to let Larry Fletcher determine that.
So tuning the "normal" rear bank for good AFR has the motor running rich.
I am a perfectionist of sorts, so after a complete rebuild I feel this isn't good enough.

Art