De-cat misfire????

[TVR Slag's BiL]

Hiya people!

The BiL's Cerb has developed a missfire! It seems to have got worse since it was de-catted. It has been to an indi who said it was due to the incorrect back pressure, due to the cats being removed? The car has new leads, plugs and 'cone' filters.

Has anyone ever had this problem?

'97 4.2 Sports pipes

[arcbeer]

Mines de-catted and I don't get a mis-fire. My first guess would be HT leads crossing or something similar.

[TVR Slag's BiL]

Thats what i was thinking, or maybe a coil gone or going. I just wondered if anyone else has had any problems with the de-cat?

[2 sheds]

I've never heard of decatting causing a mis-fire, Cerberas have minimal back pressure to start with, would agree that it is probably electrics.
tim

[joospeed]

indeed .. decat pipes are a common fit for cerbies, the indie probably fits loads of them himself .. and is probably just trying to sell you a set of new cats or summink *apologies if this isn't the case though!!* lol.

decat pipes don't cause misfires, and if your indie was no more halpful than that I'd suggest you try another indie ... there's plenty to choose from these days, sure to be one local(ish) to you with a good reputation, if you let me know where you are i can suggest somewhere.

joolz

[dai capp]

All I noticed after my decat was that it's a bugger to keep going when first started from cold and there is a slight flatspot between about 2500 and 3000 rpm.

I'm hoping that when I can afford to have the chip done the latter point will go away...

Cheers

DC

[andy4200]

dai capp said:

All I noticed after my decat was that it's a bugger to keep going when first started from cold and there is a slight flatspot between about 2500 and 3000 rpm. I'm hoping that when I can afford to have the chip done the latter point will go away... Cheers DC

Hmmm, Mine does cut out once when started as the oil pressure is building up. I put it down to the cold weather over the winter. I didn't think about linking it to the decat

[deanpluthero]

When i had mine MOT'd they put the CATS back in.
When they removed the them it was missfiering at tick-over. Obviously unhappy as it was fine when it went in.
It turned out one of the Lambda sensors had been put the wrong way round.

Dean
www.theratpac.com

[dai capp]

andy4200 said:

dai capp said: All I noticed after my decat was that it's a bugger to keep going when first started from cold and there is a slight flatspot between about 2500 and 3000 rpm. I'm hoping that when I can afford to have the chip done the latter point will go away... Cheers DC Hmmm, Mine does cut out once when started as the oil pressure is building up. I put it down to the cold weather over the winter. I didn't think about linking it to the decat

Yeah, I though cold weather, but then it occured to me that it didn't do it before and I only had the decat done March time so I linked the two - maybe wrongly.

Still the odd cut out as I'm reversing out the garage is more than compensated for by the wonderful noise when I start it again - Any excuse!

DC

[TVR Slag's BiL]

All sorted! Turns out it was a bad set of leads fitted!

YAY! DOH! Its raining!

Thanks for your help, really nice to hear from you all.

Joolz, think the brother in law will be intouch!

Thanx!