can I wire two widebands in parallel and swap between?

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can I wire two widebands in parallel and swap between?

Postby rithsleeper » Sat Dec 09, 2017 6:55 pm

I currently run one wideband and controller in the left collector on my sb 383. I have bungs welded up on every primary though so I can do some trim tables especially in the idle and lower rpm range. My original plan was to buy a second contoller/wideband to mount into the second collector for the right side of the engine and then move the second o2 sensor around for trim tables. I'm wondering if I can buy just a 3rd wideband and wire it in parallel to the second controller/wideband and then just put a 2 way switch between the signal wire.

I wouldn't have to swap the second one over and over and would essentially just be plugging and unplugging the 2nd wideband with the 3rd wideband. But I could do it very quickly and would only have to buy a 3rd wideband and not a 3rd controller. I can't really see any down side to this other than a bit of wiring. I could potentially get a 4th and make a switch board to swap between them so I wouldn't have to test drive, then swap, then test, then swap. I could do 2 swaps at a time.
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Re: can I wire two widebands in parallel and swap between?

Postby DaveEFI » Sun Dec 10, 2017 3:42 am

IIRC, each sensor is calibrated to its electronics, so you'd need to do a re-calibration if swapping just sensors.

I'm slightly confused by this. I can see one WB per cylinder being useful, but not one per bank being of any more help than one for all.
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Re: can I wire two widebands in parallel and swap between?

Postby Paul_VR6 » Sun Dec 10, 2017 6:27 am

The big issue w "switching" is the sensor always needs to be connected to the controller for heating to keep it clean. If you have one controller for each sensor and you are just switching the input to the ms between a pair of them it would work.
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Re: can I wire two widebands in parallel and swap between?

Postby benckj » Sun Dec 10, 2017 10:43 am

As others have pointed out heating and calibration required would squash this idea. Although O2’s are better for tuning using a pyro in each cylinder and a single O2 may work the best.

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Re: can I wire two widebands in parallel and swap between?

Postby Paul_VR6 » Sun Dec 10, 2017 4:36 pm

I used to use an old two channel egt gauge and run through cylinder pairs to check balance. Takes forever but that was before, well, better tech like the can-egt.
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Re: can I wire two widebands in parallel and swap between?

Postby rithsleeper » Sun Dec 10, 2017 8:18 pm

Ok, forgot about the calibration. Makes sense. Reason I wanted one per bank is to catch any problem that might happen. If one of my injectors goes on the fritz I would never know if I'm measuring the other bank.

The gas temp might be a good idea even though that is a lot of wires. I use them on my rotary spec rx7 to monitor any problems. I just want to make sure everything is perfect before really whomping on it session after session at the track.
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Re: can I wire two widebands in parallel and swap between?

Postby DaveEFI » Mon Dec 11, 2017 3:12 am

Narrowing the odds from 8:1 to 4:1 isn't really good enough for all the extra expense - to me. And the chances are a failed injector would show up with a simple DVM check on them. If one has developed a poor spray pattern, I'd clean then all anyway. A failed injector driver (with sequential) can similarly be found easily.
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Re: can I wire two widebands in parallel and swap between?

Postby 142 guy » Mon Dec 11, 2017 10:32 pm

I have trimmed fuel on a 4 cyl using EGTs. It works; but, was a bit fussy with the lower end EGTs I was using. Until you have established a baseline for the engine the EGTs don't tell you directly how lean or rich a particular cylinder is, just which are leaner or richer relative to the others. Good quality EGTs and thermocouple amplifiers don't come cheap. You can probably source an LSU 4.9 and controller for less than an EGT and amplifier. 14point7 sells their Spartan 2 for $125 with an LSU 4.9. Since you have the bungs in place, of more interest might be their MegaSpartan which can be configured with up to 8 LSUs and communicates directly with your MS2 or 3 over the CAN bus so makes data collection easier - comes with a bit of a Mega price for the 8 LSU version.
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