Those with Dual AFR’s

[Funracer]

I think there are a handful of you with CIS and an O2/AFR setup on each side of the SSI exhaust.

Just curious if they read exactly the same, or if not how much of a difference is there between sides?

Thanks

[chrisbalich]

I have EFI with dual Lambda and I'm still running open-loop so my setup is close enough for comparison. (no WBO feedback to control mixture)

The banks are not identical, but read very close more often than not. Under load, they're extremely close. At cruise, they can wander a little bit.
Consider that the architecture of these engines makes them 6 engines on a common crank and with common induction...assuming single TB intake.

Vacuum leaks, exhaust leaks, the adjustment of the valves, the condition of the cylinder walls, the condition of the rings, any difference in the injectors, condition of the O2 sensors, calibration of the O2 sensors, etc can all lead to inconsistencies in the banks or their readings. And to further cloud the issue, one outlying cylinder can sway the readings for the bank.

Are you just gathering more info?

Or are your readings far off? If so, under what conditions?

[Funracer]

Asking because I made an assumption a couple of years ago that I have not rectified. I added an O2 sensor to the pax side SSI thinking that was the way to set it up in order to set mixtures. Not sure why I thought it should go on the right side and not just behind the Lamda O2 sensor on the drivers side.

So if the two sides are that close I may just leave it alone, or have it moved next time its in the shop for something (I cannot weld).

With O2 hooked up and everything working as it should to the best of my knowledge, I am reading 45% duty cycle (bit rich?) but my AFR (O2 on the right side) shows about 15.4 at idle warmed up (bit lean?)

This does not seem to match up. Maybe the difference is I am measuring different sides.

You mention cruise and WOT. How close are they at idle?

Thanks

[chrisbalich]

L1 & L2 are within .04 Lambda at idle in my car. (.59 AFR)

15.4 AFR at idle is a bit lean. My car idles best around 13.5AFR (.92 Lambda). I've been told by many others that they idle closer to 13.0 AFR (.88-.89 Lambda). At 15.4 AFR (1.05 Lambda), my car will pop and not idle smoothly. But my car is tuned to run on 93 octane fuel that has ethanol in it. (very difficult to find ethanol-free fuel in IN)

If your goal is to set mixture, I'd set up O2 bungs in both banks. Confirm how close the mixture is in both (at multiple RPMs and loads), make your adjustment, and then go back and confirm your changes in both banks at all previously stated conditions. Tuning an engine is an iterative process and CIS makes those iterations more labor-intensive. **And all of that is assuming the CIS runs perfectly.

[Rivet]

The really crazy stuff is when you have individual lambda sensors, you can have a .84-.95 lambda spread on a pretty good running setup where your average lambda looks reasonable. On OEM calibrations that is accounted for in their fueling strategy along with timing strategies.

That is where full sequential engine management is critical to get full efficiency.

[Funracer]

[QUOTE=chrisbalich;12150694]L1 & L2 are within .04 Lambda at idle in my car. (.59 AFR)
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L1 is left, correct? And L2 is right? Which one reads .59 AFR higher than the other?

Thanks

[chrisbalich]

[QUOTE=Funracer;12150922]

Originally Posted by chrisbalich

L1 & L2 are within .04 Lambda at idle in my car. (.59 AFR)
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QUOTE]

L1 is left, correct? And L2 is right? Which one reads .59 AFR higher than the other?

Thanks

L1 is cylinders 1-3.
Typically, L2 reads a smidge leaner than L1. But it's not a consistent difference. They're even as often as they're off.

[Funracer]

Take my 15.4 and subtract your your .59 you get 14.81 on the left side. Pretty close.

Of course I can richen the idle a tad but it starts and runs nicely as is.

Thanks

[chrisbalich]

Originally Posted by Funracer

Take my 15.4 and subtract your your .59 you get 14.81 on the left side. Pretty close.

Of course I can richen the idle a tad but it starts and runs nicely as is.

Thanks

Man, if it starts, idles, and runs well, I say leave it alone.
Glad to help where I can.

[GG Allin]

- Bump, sorry nothing to do with CIS. - Dual AFR with carburetors.

How important is the distance from the header collector for the sensor location?

I'm looking at this Innovate set but I've read quite a bit that says it needs to be 24" inches from the collector. My bungs are an inch from the collector. My car is poppin' and crackling like the 4th of July, really don't want to drive it until this can be at least looked at.

[Old H2S]

Any on head problems with the Innovate AFR's?
Mine started to throw codes that they said they have never seen before and they threw me overboard??

[911 SLANT]

I run 46mm PMOs with Rarely8 RSR headers and the Innovate Duel lambda duel O2 sensors. Runs very even threw from idle to wide open throttle. Help me out tremendously when jetting carbs.

[Cherry Bomb]

I'm running Zeitronix Zt-3 with both sensors in the collectors.

Very close at idle and cruise.
Identical at WOT.