Pre-cat / Emissions ?

AnGarrek

After failing my mot with a slightly high Lambda reading, I found a very small leak between my cat and the Remus centre section.

In my inevitable style, I've just snapped both bolts that hold this lot together 🙁

As I'm removing the downpipe & cat to drill out the bolts, it seems a good time to loose the pre-cat, but will this have any effect on my emissions test on Monday ?????

Daz

Pre-cat will be fine removed and shudnt affect ure emmsiions...

winstar

no won't affect it as long as the engines hot, precat is used for cold start warmup emmision.

AnGarrek

Is it best to remove the lambda sensors from the pipe before I beat the living daylights out of the pre-cat, or leave them in and just un-plug the wiring form the loom underneath the car ?

I don't really want to stuff both sensors in the process 🙁

JohnnyN

Remove them but under NO circumstances use WD4O on them as it will ruin them.

vocky

loose the precat 😃

AnGarrek

I've removed the broken studs, and the pre-cat is gone too, but my flexi's blowing slightly 🙁

I have a link for this site for a ILOK flexi iirc, but it's going to be Tuesday at the earliest now.

AnGarrek

Just a query on the above flexi.

I've just measured my old one and it's 170mm from weld to weld, and 140mm between the end caps along the braided section.

The one recommended to me is a 250 x 51.5mm dunno..

vocky

buy the 200mm item

http://www.camskill.co.uk/products.php? ... s1411p5685

AnGarrek

Thanks for that mate, £3 cheaper too 😃

AnGarrek

My flexi from Camskill arrived today (24 hours from order) and will be welded in-line tomorrow.

Just a couple of quick questions before I put it all together;

As there's no gasket between the downpipe/manifold, is it ok to use a think smear of exhaust assembly paste, or is it ok dry ?

As I've removed the Lambda sensors, is there anything I can use to give them a quick clean before they're re-fitted ?

Thanks.

JohnnyN

Yes there is a gasket between the manifold and the downpipe! Or there should be. Are you sure its not stuck to one of the mating faces??

The standard gasket is a cardboard type coated with some sort of metallic. If its not there you must get a new one from Vauxhall. The new one is laminated steel. Under NO circumstances use assembly paste before the cats.

AnGarrek

I guess it's still stuck to the manifold :oops:

Does it have to come form VX, or is my local motor factor lightly to carry one, I won't get to my dealer until Saturday, and my re-test is Thursday !!

JohnnyN

You can try your local motor factor. Vauxhall seem to have changed their gaskets lately. They are now 2 layers of pressed steel laminated together. If you're lucky you might be able to get away reusing the original if you can find it on the manifold?

AnGarrek

JohnnyN said:
If you're lucky you might be able to get away reusing the original if you can find it on the manifold?

Thanks Jonny.

All the downpipe had a very very fine white powdery pattern on it, so hopefully the gasket is intact on the manifold.

I've searched on-line and can't see a pattern gasket for a z22se, so I doubt the motor factor will have one, but I live in hope !!

AnGarrek

Dingo35 said:
As I've removed the Lambda sensors, is there anything I can use to give them a quick clean before they're re-fitted ?

Any ideals guys, I'm refitting these tomorrow lunchtime ?

JohnnyN

Stiff brush?

notsure.gif

AnGarrek

Thanks Johnny.

They're not really dirty, rather a little sooty, I'd just thought it wouldn't hurt to give them the once over whilst they're out.

AnGarrek

Well, it passed 😃

Fast idle
CO - 0.003
HC - 1
Lambda - 1.004

Natural idle
CO - 0.001

OMG, what a difference loosing that pre cat made, I took it for a 30-odd mile stroll today after re-setting the ecu, and then gave it some beans.
It now pulls like the proverbial train all through the rev range, the bottom end torque has improved no-end, and in "Driving miss Daisy" mode I've gained 4MPG
Tick over consumption has dropped from 0.4 gal/hr to 0.2 gal/hr

Now I pi*sed off I didn't do it ages ago !!!

JohnnyN

Great news mate, well done.

thumbup