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Quick question here, what do the lambda sensors in the turbo downpipes do? I have a cat bypass pipe on my 32 and therefore the cat sensor is disconnected. A Nissan diagnostics was done (by a reputable source) and showed both lambda sensors to have no reading. I was advised to fit new ones as they will affect the performance of the car (I am doing a dyno day soon). My mechanic is under the impression that the lamba sensors need the cat. Is he right or wrong. Any advice gratefully received as new sensors should arrive tomorrow.
 

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Lamda

Hi Dave,

From what I have been told the Lamda sensor measures the amount of oxygen ? present in the exhaust gasses and feeds this information back to the ECU which in turn uses the information to tell if it is running lean/rich and makes appropriate adjustments.

someone tell me if I'm wrong please.

HTH

Steve
 

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Hi,

As far as i'm aware you don't need the cat for the lambda sensors, i think you will find very few people here who still have the cat on.
The lambda sensors only provide a basic a/f mixture ratio so the ecu can make some adjustment to the fuelling.
Without these sensors your ecu should go into "limp home" mode and should hopefully run the car richer than normal to protect the engine (albeit with reduced power), but if modified it may be risky to do a dyno session without these functioning correctly as the mixture may go lean and cause damage to the engine.

Regards,
Mike

ps I'm no expert though so please correct me if wrong.
 

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I think when a cat is not fitted a wide-band lambda sensor should be used.
You dont need a cat to use the o2 sensor
 

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Hi Guys, Just remembered that the HKS de-cat has a little lug on it for the sensor to go on to.

Dave, perhaps there is something similar on your de cat pipe.

/Steve
 

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lambda

Dave,
you DO need the sensors, not replacing them will put the ecu into a default safety map which will allow the injection of excess fuel due to the fact it can no longer monitor the ratios, The cat is not a part that plays a role in the engines mapping function and is there mearly as a means of controlling emissons.
Garth.:D
 

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Discussion Starter #7
lambda

Thanks guys, that is what I needed to know. Will sort. By the way no lug in cat pipe :(
 
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