Flipping Catalytic Converters blocked again!

After getting new cats fitted at a hefty cost from the dealer, they flipping things are blocked again...

My GTA is really starting to get on my nerves, just replaced cambelts, tensioner, water pump, thermostat, idlers, oil, spark plugs, intake manifold gaskets, suspension bushes,.. and now the cats are blocked and she's hobbling.

Tell me guys, if i fit the supersprint full exhaust system, what will happen re: the lamda sensors. The GTA has 2 cats on the manifolds and another cat in the exhaust later on about halfway down the under carriage.. does the supersprint header have a place to connect the lamda sensors, or can they be bypassed and the ECU fooled into taking readings from the cat in the centre of the exhaust?

The manifolds and the de-Cat sections have places for the Lambda sensors.

Sorry to hear that Stephen, if it is the cats that are damaged and not any of the lambda's it would make sense for the difference in cost to go for the Supersprint.

The system is good to go, all sensor fittings are there and the ECU adapts well with fuelling. Had it checked, idle/cruising is at stoich, runs rich on wot at the top end which could be normal anyway for the GTA engine... though I am after some opinions on that preferably from someone not trying to sell me a remap

Think I'd be correct in saying that as it's Euro III the last two sensors after the cats are there to monitor the efficiency of them, remove the cats altogether and the MCF message will come up. Question is, with a custom made exhaust if you can remove the main cats while having just the warm up cats on their own, if they would be enough for these sensors, afaik they cannot be mapped out.

In 7,000 miles with full system only had a message come up once, not really counting it either because I'm certain it was dirty fuel, needed to fill up off the beaten track driving through Belgium once as I was on vapours, diag read cat below efficiency threshold. Have never had a problem on UK 95-99, worth mentioning still if fuel quality could be an issue.

Originally Posted by David C

The manifolds and the de-Cat sections have places for the Lambda sensors.

David C, thanks... you always have answers!! ... i really appreciate the advice, I was slowly losing the plot.

I will get a hold of the local superspint boys and give them a shout.

Thanks to caldo also for your post...

Caldo, David C, have you guys heard of Bartoli Exhausts in Italy, apparently they manufacture full systems for Alfa Romeo, Ferrari, Lancia, Maserati and Fiat?

First I've heard of them, strange... google (bartoli marmitte alfa) and Alfa is cached. Go to the website

Bartoli - Realizzazione marmitte in acciaio inox ad alto rendimento

no more Alfa, maybe they used to do them...

The only other alternative for headers I've come across is Unicorse / Orque both of which look remarkably similar to one another.

Originally Posted by Stephen Manjai

After getting new cats fitted at a hefty cost from the dealer, they flipping things are blocked again...


Tell me guys, if i fit the supersprint full exhaust system, what will happen re: the lamda sensors. The GTA has 2 cats on the manifolds and another cat in the exhaust later on about halfway down the under carriage.. does the supersprint header have a place to connect the lamda sensors, or can they be bypassed and the ECU fooled into taking readings from the cat in the centre of the exhaust?

They have 4 cats not 3. - 1 in each manifold and 2 in the centre sections.... Or at least my bro's 03 147 GTA does. I guess 156's could be different.

The question is: Why are your cats becoming blocked.

I've seen this a couple of times on twin sparks. They had both been run with blocked cats and they both ended up eating their cam shafts as a result.

Its probably a problem with a wiring to a coil pack or a problem with the coil pack itself. Allthough faulty injectors, plugs, MAF, lambda etc could all be to blame too.

Originally Posted by Chris155

They have 4 cats not 3. - 1 in each manifold and 2 in the centre sections.... Or at least my bro's 03 147 GTA does.

Yes the Euro3 V6 156/147 have four Cats.

Originally Posted by David C

Yes the Euro3 V6 156/147 have four Cats.

Yes David C, correct. My GTA has two cats on the exhaust manifold just as it exits the motor, and then two in the centre pipe, and four lambda sensors, one for each cat..