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Air/Fuel Measurement on the Move

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I'm starting the think about fitting a Lambda sensor to the exhaust of my TR6, with a gauge inside the car so Air/Fuel ratio can be monitored while on the road. There's been a lot of discussion of this topic on the Reliant Scimitar forum and some Scimitar owners have successfully installed Air/Fuel gauges:




Look for the topic "homemade lambda sensor / probe. It works!!!".


It could be a great way to check fuelling on PI-equipped Triumphs and enable accurate calibration of the metering unit under varying load conditions. A viable alternative to setting up PI fuelling on a rolling road perhaps?


Have any of the assembled experts here any experience of fitting an Air/Fuel ratio gauge to a Triumph PI engine?




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Nigel, I fitted an Innovate unit to my Webered TR6 a few years ago to help me set the carbs up. It uses an O2 sensor that goes into the exhaust. I fitted a bung just before the flange that connects the manifold to the downpipe. The cast iron drills easily and the steel bung for the sensor is just brazed into the hole.


It did provide some data and has data logging capability to a PC via USB cable but I wished I had more sensors that could give me the full picture like speed, rpm, what gear etc. One thing I have not tried yet is positioning the gopro to capture the whole picture, eg watch the engine go lean when accelerating through 3000 rpm in 3rd etc.



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There are two sensor systems on the market.

The one at scimitar is unsuitable because its only precise at Lambda =1

although its better than nothing!


We need a fullrange/wideband system like Stan is talking about

Innovate does those systems, LC-2 or LM2 is the current version

but there is also a new digital system that has all required electronic in the instrument.


Would put the sensor a bit further away from head

under the starter in the downpipe with sensor in 10-2 o clock position is good

although you only catch one stream of exhaust with that setup.


Rolling road helps to get quickly setup for max power.

Today with the cheap and precise Lambda tool I would prefer

to do the whole setup on the street.

Both need a feedback about exhaust gas quality.

Edited by TriumphV8
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I have been using an Innovate system with the exhaust clamp fitting, and trying to improve the running on my PI system. I chose this exhaust fitting as I can tune my other cars with it, rather than it being fixed into one car.

I have had some success in fine tuning, but haven't been able to get it completely right, I think I need Neil to do a proper calibration, so that I can then see how it goes. I think the base mechanical settings are not correct inside, so making any adjustment on the vacuum side are a bit limited.

Its great as you can record up to 40mins of driving, and then download to a computer. But it does need a few more inputs to know just where the increases/decreases occur

On going work in progress!


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Yes indeed nothing beats real measurement of AFR.

The sensor you need is known as a Wideband UEGO. The wideband is very important for tuning AFR. Lambda is no good.

Lots of companies sell the electronics but the UEGO sensor as fas as I know is made by Bosch.

Best to buy electrickery kit that has a heater built into the controller- the sensor only works when at correct temperature. And fit it so it doesnt get wet with condensation in the exhaust, and not too close or too far from the manifold. And with no exhaust leaks upwind of the sensor.

I bought one of these:


but it does not log the signal.


Edited by Peter Cobbold
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Many thanks to all for your experience and suggestions. You have confirmed my view that AFR measurement under real driving conditions on the road is the way to go. Narrow band looks too limited in the info it can provide, wide band is clearly the way to go. The UEGO kit looks very tempting - something for my Christmas list perhaps.




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I have a dual sensor Innovate LM2 installed in my Vitesse (dual as I need to set two carbs individually rather than just get an average) and am also logging Throttle Position and RPM. Hopefully if all goes well I will also be logging carb piston lift after this winters rebuild.


Wideband sensors are what you need.


I have been amazed at what I have learnt over the last 12 months using it to set up my competition engine. It was just a shame it cant tell me what the knocking noise is coming from deep inside the engine. But strip down starts this month :-)


I'm not saying that the Innovate kit is the best, it was just the right set up for me at the right price point (do some searching before buying) as it will log and play back without having to plug into a computer (although to study results in detail you still need to do that).


Innovate documentation is good, their direct support can be either stunningly good, or bad. There used to be a good innovate forum with loads of useful stuff, but innovate took it down because of all the abuse they got.


Good kit, but like a lot is really aimed at modern engines and management systems, if you are retro fitting to old engines then you will have to be inventive.


I should qualify that, if all you want is wideband logging its great, its hooking up all the other stuff where you have to plow your own furrow :-)




NB. If you are installing a bung in the first half of the exhaust then make sure you get the long reach ones so that the bosch sensor doesn't sit right in the exhaust, the results are much cleaner that way and the sensors will last way longer.

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