help! car stutters and backfires.. not limp mode?

[rob_sri]

Cars been behaving really strange.. couple of days after having a decat and second lambda sensor fitted

it pops loads when really cold..

but when you drive sometimes there is power and sometimes it doesn't respond..

you can have your foot on the floor and it will hold at whatever revs it was at 3-4-5k it doesnt matter and almost sound like its hitting the limiter and popping.. power will just hold and then snap back.. which if you have your foot to the floor trying to get it to move is interesting!

ive done the dial test and its come back with 'h' where there was nothing a few days back

i've also unplugged the new downstream lambda to see if this makes a difference but it hasnt done a thing!

cars just been fully serviced with belts done etc and is very well looked after.. got to be something to do with the decat/lambda i should imagine as this is the only thing thats changed but i have never heard of a car acting like this because of decat/postlambda

anyone had any similar probs before?

going to get a diagnostic plugged in tomorrow if i can

 

[montana]

coilpack?

 

[rob_sri]

does this sound like the usual symptoms of a coilpack?

 

[rich-6]

Mine does it occasionally when cold, As do most others, I think the general rule is to live with it.

I have however noticed s**t fuel makes mine do it, Normally i fill up at Shell on their unleaded and its fine but used sainsburys pezzy 95 Ron on a couple of fill ups and it is down considerably on power, practically stalls itself, pops & bangs all the time when cold.

 

[rob_sri]

was doing it alot the other day even when warm... like holding at certain revs and not revving past... like id be driving at say 3 increasing to 5k and it would get stuck at like 4 and wouldnt let me rev past there and it would burble n make a weird noise

 

[Pretty Funked Up]

Mine did as you describe when the CAT collapsed internally. Obviously it cant be that as youve removed yours but I would say its CAT or lamda sensor related.

 

[rob_sri]

may well scrap the decat then and go back to standard! until i can afford a rolling map

thanks dude! thats the answer i was needing!!

strange tho yours did the same!! what did yours do then? how would you describe it?

 

[rob_sri]

fixed!!
so that people know ..if you're are reading this with similar issues it was the pre cat lambda sensor that was broken.. i took it out and it rattled!!.. fitted a new lambda sensor and it runs like a dream! absolutely spot on! so happy