OAP Posted June 9, 2002 Share Posted June 9, 2002 If I replace the catalyst and sensor on my SLR with a 4-2-1 section, will the ECU need remapping? Link to comment Share on other sites More sharing options...
EFA Posted June 9, 2002 Share Posted June 9, 2002 No. The cat is a passive device. ECU knows nothing of its existance. Fat Arn Visit the K2 RUM siteid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Edited by - Fat Arnie on 9 Jun 2002 15:34:29 Link to comment Share on other sites More sharing options...
OAP Posted June 9, 2002 Author Share Posted June 9, 2002 Thanks Arnie. What does the sensor do that is situated in front of the cat and is wired to the ECU? Link to comment Share on other sites More sharing options...
jf_renard Posted June 11, 2002 Share Posted June 11, 2002 Hello OAP. The sensor is an EGO (Exhaust Gas Oxygen)sensor. Its purpose is to inform the ECU of the quantity of oxygen in the exhaust gases, for it to be able to maintin it in a range compatible with the catalyst function. If you take the sensor away, there will be no input into the ECU and I don't know how it will be interpreted. I think the ECU will tune the injection on either "full rich" or "full poor", none of which seems really good... Anybody knows more on the subject? Jeff Cosworth 1600 BDR Link to comment Share on other sites More sharing options...
sjwb Posted June 11, 2002 Share Posted June 11, 2002 Explanation: Lambda sensor (O2 sensor) (Oxygen Sensor) exists for the following and is situated above the catalyst in the Caterham scenario. A comparison between the level of oxygen in the exhasut gas to that in the atmosphere produces an output (electrical) signal. The signal is used by the engine 'closed loop' fuel strategy to make FUELLING corrections and so CONTROL overall emission levels. The fuelling correction is achieved by varying injector pulse duration. Nothing else to it, no mystery, simply this. Where there are two sensors - one upstream and one downstream of the catalyst, the comparison of upstream and downstream signals allows determination of catalyst conversion efficiency. Steve B Link to comment Share on other sites More sharing options...
Mick Day Posted June 13, 2002 Share Posted June 13, 2002 So once you've removed the catalyst you can safely remove the lambda probe. While you're at it why not remove the charcoal canister & all the other gubbins that goes with it (weight reduction etc.). Mick Link to comment Share on other sites More sharing options...
OAP Posted June 14, 2002 Author Share Posted June 14, 2002 Thanks sjwb, Does this mean the engine will run either rich or weak as Jeff suggests? Link to comment Share on other sites More sharing options...
Slipper man Posted June 14, 2002 Share Posted June 14, 2002 With my R500, the rearmost exhaust pipe has a threaded bush with a bolt in it the same size as the sensor. You simply remove the sensor from the cat, and screw it into hole on the down pipe. Works fine then. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 15, 2002 Share Posted June 15, 2002 No Mick. The ECU is still reading the lambda sensor and is making fuelling judgements based on it. No sensor equals random fuelling unless you know what the ECU is up to. Peterid=teal> 253 BHP K-seriesteeth.gif, no gearboxbum.gifid=red> Link to comment Share on other sites More sharing options...
OAP Posted June 22, 2002 Author Share Posted June 22, 2002 Keith, You are absolutely right - when I first read your posting I misunderstood your reply, and was looking for a threaded bolt rearward of the silencer. Now I've found the bolt on the 4th primary I've been able to get rid of the cat. in favour of the 421, and seal up the air leaks around the ends of the primaries. What a difference! Runs clean and easy at low revs, picks up 10 times better, a complete transformation! Link to comment Share on other sites More sharing options...
Mick Day Posted June 23, 2002 Share Posted June 23, 2002 Sorry Peter, forgot to mention that the oxygen feedback rate needs to be reduced to zero at the ECU. Mick Link to comment Share on other sites More sharing options...
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