Decat fitted minus Lambda sensor, 182 cup.

[Cuplica]

Hey guys, after impatiently waiting on garage after garage to tell me they're too busy, I fitted a decat myself. I couldn't release the lambda sensor from the cat so left it off the vehicle. For some reason, my economy fluctuates a lot more then usual. It was as low as 9mpg tonight. My rationale is that it is compensating for the lack of sensory information so is just throwing fuel into the cylinders. But I'm no mechanic.

Also, it is chuffing a lot from the joint between the decat and the manifold and there has to be a gap there. How can I remedy this without cementing it together making it impossible to get off?

At the moment I am thinking about getting a new manifold to just seal it off legitimately. Would anyone reccomend a particular manifold? It's a 2005 Clio 182 cup.

:dead:

 

[Oscar88]

i don't quite know what you mean by cementing but exhaust paste is used for a reason. it's up to you wether you 'cement' it, or apply a small amount to seal the joint. unfortunately with metal you cannot create a perfect seal, so you'll need a gasket and / or exhaust paste. you're also correct on the fluctuating fuel economy. with no sensory information to let the car know how well it's fuelling, it's going to constantly be on the rich side and switch to lean and then back to rich as if it's panicking. the best thing to do is map the car as soon as you decat to set the fuelling to it's optimum setting.

 

[Cuplica]

If I was to replace the Lambda, do you know if this would make any difference?

 

[Oscar88]

i'm not meaning to sound cheeky but you'd need to understand what the lambda sensor does and exactly how it interacts with the ECU it's soul purpose is to monitor the performance of the cat and adjusts fuel accordingly. with no cat, it will still make your mpg go crazy in a negative way. most people can happily live with it because they are loaded and don't care about the price of fuel lol. like i said man, the best option is to map it accordingly so that the fuel settings can be set to an optimum ratio for throttle positions and load and this in theory bypasses the lambda sensor

 

[Steven103]

The pre-cat lambda sensor is used to control the AFR only.

The post cat lambda is only used to check the catalyst is working properly. It has no direct impact on the AFR.


This is why when you fit a decat or remove the 2nd lambda sensor you'll probably find you've got the orange emissions warning light on the lower right hand side of the dash.

What makes you think you need a new manifold to cure the blowing centre joint? Was the flange on the manifold damaged? Are you sure you reassembled all the bolts, cups, washers, springs etc in the correct order? Was the gasket still in good condition? Really you need to answer all of those before jumping to a conclusion.

 

[James28]

The rear lambda won't be affecting air/fuel ratio. Which is the one you removed.

Sounds like you need a new genuine manifold>decat fitting kit if its leaking badly. The other end on the olive joint use silicone sealant not exhaust paste.

 

[Cuplica]

I think I need a new manifold because it looks very rusted. Maybe if I sanded it down and got rid of the flaky bits it might sit flush. I've bought some exhaust sealant and intend to attempt to apply it later on today or tomorrow morning.

The fuel consumption was sitting at 15.2mpg just stationary.

I don't mind any help and advice whatsoever, I'm not too clued up on these things but it seemed such a trivial mechanical effort I just cracked on and did it myself.

I also need to regrease the CV boot until I buy a new drive shaft.