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Lambda sensor removal

sbloxxy

sbloxxy

New member
Has anyone got any ideas on how to remove a very stubborn lambda sensor? I'm trying to fit a de-cat pipe and removing the sensor from the cat converter is proving to be a pig of a job because its seized solid. I've tried all manner of spanners and wrenches, I've hit tried to 'encourage' it with a big hammer and I've even tried a plumbers wrench - which usually frightens most things into loosening themselves - and its still absolutely solid. I also tried running the engine to heat the exhaust - still nothing.
Does the sensor do anything when the cats removed anyway? Its now soaking in WD40 overnight but if anyone has any ideas, please let me know.
 
Well, my experience was to break it in half, then use a socket to remove the old one. Sorry that's not a lot of help, but I was changing mine out so I didn't worry.

I had used some of our best (at work) release agents, and it simply wouldn't move.

Kevin.
 
Stephen,

I think Kevin's solution is the best one. I suspect that after your efforts all you are likely to achieve is to finally remove a non-working lamda sensor!! The Lamda sensor is used by the DME to determine the optimum fuel/air mixture by monitoring the exhaust gases. If you don't fit it the DME will default to a mode which will result in a less than optimum mixture. It will still run, perhaps not as efficiently. Better to have it though. It's worth putting a new one in.

Regards

Dave
 
I've since had a trawl around the internet and it seems that removing a lambda sensor in one piece is next to impossible. A further trawl revealed that Euro Car Parts are about the cheapest for a new one but theirs is an unspecified make; I've been told that cheap lambda sensors can have a very short lifespan - any experiences? I also had a look at the Ninemeister site - they mention that replacement of the sensor after a de-cat is not strictly necessary and they vaguely refer to the need to connect the sensor wires together in order to allow the car to run properly. Any ideas on that one?
 
Stephen,

Do you have Adrian Streather's book on the 964?? If not, I'd strongly recommend it since it covers subjects like this in some detail.

The Lamda sensor produces a voltage between 0.15 and 0.9 volts which the DME uses (among other inputs) to control the fuel/air mixture. If the Lamda voltage exceeds 1 volt the DME will default to what is called "Open Loop Mode" and will record a fault in the DME and will be difficult to drive normally. It's important to note that the Lamda sensor "generates" this voltage - it is not a resistance reduced voltage from a controlled supply. The second wire to the sensor is the "heater" supply which is only active for the first 90 seconds from startup.

If you do not fit the sensor, linking the wires will put the initial startup "heater" voltage back to the Lamda input on the DME, causing a fault. The correct solution is to jumper the DME to prevent it sampling the Lamda sensor. This will result in a slight over fueling, slightly worse fuel consumption and, probably, mildly better performance.

On replacement, it seems to be recommended that you only use the Bosch replacement as supplied through Porsche (or Bert Gear) as there appear to be common problems with others in wet weather. The Bosch unit is, apparent;y better sealed against moisture.

Hope that helps.

Regards

Dave
 
Thanks for that Dave. Removing it altogether sounds like a non-starter and you've confirmed what I thought about cheap sensors - I've just ordered the Bosch one.
Thanks again.
 
We find removeing the most stubben Lamda senser is to soak it in deisel, this works even better if you can undo it very slighty so the deisel runs down the threads.If you have to heat it up to remove 9 out of 10 times you will strip the threads.

Good luck

Ian
 
New twist to this one: I was at a track day at Elvington today and when a sound reading was taken from my car, it registered 100 decibels. My car has the standard exhaust system - albeit with the slightest blow from the joint behind the cat converter (knackered clamp) though it does have a HK cone filter. I'm now worried that if I go ahead with my plan to fit a de-cat pipe, I'll be too loud for track days- the usual limit is 105db. Anyone got any idea of how much louder a de-cat pipe will make my car?
 
Stephen,

I've got nothing precise that will help other than to say that the cat bypass will make it slightly noisier, but I wouldn't think by much. Bear in mind that the "silencing" function is provided by the primary and secondary silencers, the cat merely converts some of the gases to less noxious forms. Also bear in mind that 103dB is twice as loud as 100dB.

I know a few owners who have Cup Pipes or G-Pipes fitted struggle to get under the noise limits but my guess is you'll be OK as long as you have both silencers fitted.

Think yourself lucky - my cat bypass/Fabspeed dual out measured 108dB at a test last year at Goodwood!!! That's more than 4 times as loud as yours.

Regards

Dave
 
Mine was 104.5 at Goodwood, funnily enough last year....

Standard zorst except I have a G pipe

kevin
 
Another thing you have to remember is that with a cone filter the induction noise might be just as loud the exhaust note,We come across quite often when we are doing a DB test you put the noise meter the same distance away from the airfilter as the exhaust outlet and you would be surprised .

Ian
 
I'm sure you are right - the cone filter has made a big difference to the amount of sound produced. I think it sounds superb - fairly discreet til you hit around 4000rpm and then it snarls beautifully. Its an item I bought new via Ebay for about a tenner, made by HK in the States. Highly recommended.
 
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