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Discussion Starter · #1 ·
Hiya

i have just had my exhaust (cat back system) done on my mk3 1.8i 8valve cavalier, and i have just purchased a decat pipe also.
I want to put the decat pipe on but am worried incase i come across any problems, i.e engine management light, what to do with the cat sensor (if it has one)
so i was wondering if anyone knew of any problems or do we think i'll be able to do this without any?
thanks nicola.:Cool2:
 

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Right, the only sensor you may have is the Lambda sensor, but you may not have one on your Cavalier, Im not familiar with the 1.8i model, but we have loads of other members that do, and im sure in time someone will come acorss your thread and be able to point you in the right direction.
 

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The hego sensor is in the manifold,then theres a seperate downpipe,then the cat.The cat is easy to get at and change.Got to be honest though its difficult to get much more power out of the 1.8i.
 

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Wouldn't give you many extra horsepower, but should be worthwhile anyway.

As long as you've got the right decat pipe, this job should be easy. This is how you do it on the 2.0 XE; your car is probably very similar:

There's 2 bolts at the front end of the cat - best to soak these with some penetrating oil before attempting to unbolt them to minimise the chance of the shearing-off. Don't completely inscrew them as you can use them to support the weight of the cat on a couple of threads of the bolts.

Loosen the bolts at the rear end of the cat; mine has 3 bolts and a metal gasket.

Ideally, get someone to support the weight of the cat while you remove all the bolts, springs and gaskets, and lower the cat out of the way. Don't drop it if you want to re-use it for your MOT. Keep it safe somewhere.

Recover the gaskets and resuse them if they're OK - if not, get new ones. if you don't know the condition of the gaskets, get new ones before you start the job. Same goes for the bolts and springs.

Offer up the decat pipe and bolt in place. The gasket at the front is flexible and you shouldn't use any exhaust sealer (like Gun Gum) on this joint. Use some sealer on the back joint (smeared around the gasket) to ensure a good seal.

Leave the lambda sensor where it is.

Good luck :Cool2:
 

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Discussion Starter · #7 ·
thanks for all the help, i know i am asking too much to get more power out of a single point injection 8valve 1.8 but i have gotta try cos the insurance man won't let me have anything bigger:down:
think my other half is gonna leave it till sunday to fit when he has got more time but i'll get him to read all the above suggestions when he gets in,
cheers:Cool2:
 

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Hi if you want you could try drillin the airbox( thread in how to ) nice an easy to do. Dont know if any more power but worth it for the noise alone;) . Don it on my 1.8i sounds great:Cool2: .
 

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you won't get any problems with the engine management light as the lambda sensor is fitted before the cat. Nice easy job to do, but as said, won't really give you a lot of power. having never tuned a 1.8, i don't know the best way to go, but i'm guessing cam, head work etc to give you some kind of an increase.

HTH
 
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