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MG MGB Technical - O2 sensor - exhaust clamp

Most AFR kits are designed for permanent installation via a weld-in plug in the exhaust. I note that Innovation Technologies offer a special clamp that allows the sensor to be mounted temporarily in the end of the tail pipe. This would be better (for me) than a permanent installation, as I could then lend the sensor to other club members for tuning and evaluation.

Does anyone know if there is anything special about the clamp, or can one simply use a G clamp or similar?
J H Crighton

I have my A/f gauge fitted full time but I have taken it out to use in other cars. Its plug and play and a sump plug fits the hole. I have lent mine a couple of times but you do need to know what fuel they are using as leaded or some racing fuels can shorten the life of the sensor. Denis
Denis4

Thanks Denis. I will install the port in my exhaust - and I realise I can remove the sensor and blank the hole. I was just wondering whether it is feasible to use the sensor on other cars that do not have a port in their exhaust, i.e. whether it is possible to get reasonably accurate readings simply by inserting the sensor up the tail pipe.
J H Crighton

Actually, this is one of the jobs still on my list. I might take the opportunity here to clarify some points. I want to permanently install the unit, although as you say Dennis, my kit also has a blnking plug. I was going to get the local exhaust man to weld in the plug into the exhaust, but yuor tip I think was make sure it is inclined slightly upwards so that moisture does not accumulate. The thought I had was would a braze into the exhaust system be sufficient or does it have to be a weld? I might be able to braze it myself? Mike
J.M. Doust

Mike, Denis. Do either of you have any knowledge or experience relating to temporary mounting the sensor in the end of the exhaust pipe??

regards john c
J H Crighton

JH Crighton, no I have no personal experience of the 'stick it up the exhaust pipe' jobs. Though, I cannot see why it would not work. I have a suspicion that the sensor is different, measures differently as there may be other gas contaminants by the time the burnt mixture is down that far. Perhaps they are more sensative? Google an old Autospeed article entitled Air/fuel meters, I thought these quite useful. Mike
J.M. Doust

Mike

Thank you for that. The article is interesting but does not address my particular question.

However another article at that site did give me a useful clue. Titled "Real World Air/Fuel Ration Tuning" it has a photo of a tail pipe mounting. It involves a small section of pipe slightly smaller in diameter to the exhaust pipe, with a port for the sensor. That smaller section with sensor is simply introduced to the end of the exhaust. It 'presents' the sensor to the gas flow in the same was as a permanent installation closer to the engine. Provided it is a heated sensor the temp will be ok even though it is way back from the engine.

I plan to have a permanent port (with blanking plug) put into my exhaust, but also make up a temporary fitting so that it can be used on other cars (e.g. other club members).
J H Crighton

As long as you have the heated sensor it will work OK at the rear of the exhaust pipe. It may take a little longer to reach the required temperature.
Mike I welded my bung in with small arc rods but braising should work if you get the area clean enough.
My engine pipe is larger than OE, with a small section joining the front and rear pipes, where the front muffler should be, so I could slip it off easily and do it on the bench. An exhaust shop would not charge a lot.

Denis
Denis4

Thanks Dennis, yes the sleeve idea occured to me also, as my whole exhaust system is welded, I cannot take it off unless I release from the maifold all the way back. I think I will get an exhaust place to make me a sleeve. Oh, and JH, yes that was the clue a small sleeve with the sensor just hung on the exhaust outlet at the back, simple. Mike
J.M. Doust

"but braising should work"

Is that 'beefy' enough :o)
PaulH Solihull

The sensor should be far enough up the pipe to avoid contamination with outside air. 12" up should be OK, not right at the end. And a heated one as has been mentioned.
Art Pearse

This thread was discussed between 04/10/2011 and 07/10/2011

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