Misc: Everything Else Air Fuel Gauge 02 Sensor Lambda Sensor

Magnetoman

Well Known and Active Forum User
VOC Member
Maybe Magnetoman could put a thumbscrew in his tailpipe and go for a ride without the bunsen valve and see what the A/F sender has to say about that?
Applying thumbscrews to the exhaust in that video didn't result in much cooperation from the engine so I think I'll pass up the opportunity to drill a hole in my Gold Star's silencer.

Returning to temperature, I suspect this is a non-issue for us since we only have one or two 500cc cylinders sending hot exhaust past the sensor, whereas car engines have six or eight cylinders providing that much more heat to dissipate. However, attached is the caution and work-around from my LM-1's manual.
HeatSink.jpg
 

Mike 40M

Well Known and Active Forum User
VOC Member
Stu mentioned an idea of pushing a long tube up the exhaust. His idea might be the easiest way to get a thermocouple in the exhaust system without drilling holes in the pipe.
 

Cyborg

Well Known and Active Forum User
VOC Member
There goes me assuming again. I figured you had a sacrificial Gold Star muffler on the back of the test pipe. I wouldn’t do it in a effort to find more grunt, but just curious to see if it would reduce the amount of air coming back through the muffler and cancel out the need for the bunson valve.
The heat sink is interesting. Even with my sensors higher temp limit (800C) I’d be inclined to install one anyway and have the bung a little further from the tip of the muffler. The heater might have to work harder, but I’m sure it the Alton will be happy to oblige.
 

Cyborg

Well Known and Active Forum User
VOC Member
If John had those sensors that close to the port and they survived for a couple of years, then it would appear that too high of an exhaust temperature probably is as you say a non issue. Plus it is possible that they are older sensors or O2 sensors (not wide band A/F) and want less than 800C EGT.
 

Magnetoman

Well Known and Active Forum User
VOC Member
I figured you had a sacrificial Gold Star muffler on the back of the test pipe.
The heat sink is interesting. ... The heater might have to work harder,
I have several sacrifice-able Gold Star mufflers, but only one of them is "twitter-like," and it's aftermarket so I couldn't count on its behavior being identical to the real thing. However, given how far up the muffler my clamp-on sniffer fits, I know air is sucked at least that far so it's hard to imagine a bolt in the air stream would be enough to have much of an effect. Actually, given that the external clamp-on probe is a lot larger obstruction than that of a single thumbscrew we already have the answer -- a bolt wouldn't eliminate the effect.

Yes, the only downside to a heat sink is it will suck away more of the heat from the exhaust forcing your electrical system to make up the difference needed to maintain the operating temperature. Since your Alton gives you Watts to burn this wouldn't matter. Maybe I mentioned this in an earlier post(?), but after an initial ~30 sec. warm-up when the unit is turned on my free-standing 4.2 sensor draws just 1 Amp. This means when bathed by hot exhaust it draws even less (although, I haven't measured that value).

27041
 
Last edited:

Cyborg

Well Known and Active Forum User
VOC Member
When I do weld in the A/F sensor bung, I’ll try and locate it with that heat sink in mind. I have a 3.2 V6 from a 91 Acura holding down my workbench. The O2 sensor is located within inches of the rear exhaust port and surrounded by a heat “shield”. So other than possibly hooking up a probe to the bung ( just out of curiosity) I think I’ll just forget about the exhaust temperature thing .... still want to find a sacrificial pipe so I don’t knacker the new one by not feeding it enough fuel right out of the gate.
 
Last edited:

vibrac

Well Known and Active Forum User
VOC Member
Am i missing something? My mate at the rolling road said let's put a sensor in the pipe it's better than a stick up the end. He got an 8mm nut drilled a hole a foot from the port brazed the nut on, added in a sensor in we ran the run. Then he stuck a cap screw in the nut. The nut is at the back of the pipe only the timing cover can see it and it's not telling anyone, what's the problem?
 

BigEd

Well Known and Active Forum User
VOC Member
VOC Forum Moderator
Am i missing something? My mate at the rolling road said let's put a sensor in the pipe it's better than a stick up the end. He got an 8mm nut drilled a hole a foot from the port brazed the nut on, added in a sensor in we ran the run. Then he stuck a cap screw in the nut. The nut is at the back of the pipe only the timing cover can see it and it's not telling anyone, what's the problem?
If you didn't mind having another nut on the pipe you could weld on another further down and see if the readings were different.
 

oexing

Well Known and Active Forum User
VOC Member
To be open, I don´t quite know what it is all about A/F sensors, sniffers and all that stuff. A modern car engine mainly uses data from the lambda/O2 sensor welded somewhere along into the exhaust pipes, some have another sensor a bit behind. No sniffers in the exhaust on the road I guess. So I did just that on two Horexes, pre and post war, a Honda Clubman, a BMW R 69 S and , ah, a Ford Capri and the 3.8 E-Type. That worked for me and you don´t need a second hand ex pipe, just find a place that is not too visible for onlookers.. Now look at my photos, you better do TIG welding the M 18x1.5 adapter with stainless and in short intervals and you even keep the chrome shiny.
The sensor has two wires for heating it so the distance from ex valve is not critical at all.
The sensor is hooked up to a mini digital voltmeter that tells me 0.5 V is perfect, up to 0.7 V is a bit rich but OK, below 0.5 V is too lean. I could use a rolling road at my friend´s workshop but prefer to do road tests for better feel at all throttle positions and test driving as long as I like .

Vic

P1030162.JPG


P1030159.JPG


P1030156.JPG


P1030172.JPG


P1030176.JPG
 

Cyborg

Well Known and Active Forum User
VOC Member
Am i missing something? My mate at the rolling road said let's put a sensor in the pipe it's better than a stick up the end. He got an 8mm nut drilled a hole a foot from the port brazed the nut on, added in a sensor in we ran the run. Then he stuck a cap screw in the nut. The nut is at the back of the pipe only the timing cover can see it and it's not telling anyone, what's the problem?

The discussion about placement of the bung arose because of magnetoman’s experience with reversion causing his sensor to be exposed to interloping O2 molecules plus the caution in the installation instructions about not exceeding the heat limitation of the sensor. Having no idea what the EGT is in a Vincent engine I was trying to figure out how close I could get to the exhaust port or more importantly how far away I could from the tip of the muffler. I haven’t looked to see what valve overlap is on Gold Star cams compared to Vincent MK2, but no point in putting the bung too far from the port and end up chasing moonbeams. As for the problem, I think we’ve figured out that that EGT is not an issue. So all I need to do is weld it in at an angle (reasonably close to the exhaust port) that won’t allow moisture to collect in the sensor.

I by no means fully understand the reversion aspect of this, but after doing some reading, it would appear that I'm not alone, even among some professionals. Its interesting that it worked out in your situation and appreciate the info, but as I understand it... just because it worked for you doesn't necessarily mean it would work for me. Depending on valve overlap and muffler design, you might be able to get away with a location that in my case would require one of those bunsen valves.
 
Last edited:
Top