X30XE Exhaust blow vs. Power Q

[jtypecav]

Hi all, looking for a bit of friendly advice. NO LONGER ABOUT XORST - subject changed but OP kept below. Now more a general running issue query / ecm light after start. See new detail at end of thread. Cheers!

I've always assumed that a blowing exhaust, particularly from higher up the system towards the manifolds (and any sensors themselves) can cause a loss of power and more general lack of sophistication in the way it runs.

However, there are loads of completely contrasting stories with so called technical justification as to why / why not a power loss will occur ranging from "backpressure being a myth.." - which of course is nonsense through to stories of 20-30bhp being lost. The car is currently running the same custom system which it had on an original 8v 2.0 and whilst I know it is not large enought, it has always been free flowing and there has never been a cat or anything else to be blocking / reducing flow. Hopefully the answer will be a lot more simple than this email, but as the car is a one-off figured it was better to be detailed! Any additional illumination welcome cheers.

[Mark T]

I've run my MK2 3.0 and MK3 2.5 with just the downpipes.

Ran fine.

[Grim Reaper]

My volvo is on a sideexit with 1 bend ( ) and it's fine. I've just lost abit of low end torque and its only economical to drive in the higher rev range

[jtypecav]

Thanks for the advice so far guys, guess I should double check bits elsewhere. Perhaps it is just missing a bit of the torque somewhere, I've gotten so used to it as a daily now.

[jtypecav]

If it is not the exhaust / manifold what else could cause power delivery to still be smooth, maybe taking a a second or so longer to start but no ecm lights or misfiring or anything.. but the car to just not have quite the same kick?

Clutch slipping? Fuelling? (it's not that I'm just used to it either ) Any suggestions welcome as she's away to prospeed this soon with the rollers looming shortly after!!

Really hope its not the HG on the way out as that was done 8 months ago... Just one of those hard to chase down issues I guess!

[jtypecav]

Don't know if this gives anyone a light-bulb moment or not. But the management light now lights for a few seconds after the car has started and then clears. Car still down on poke but running reasonably smoothly. Has had new crank sensor and AFM so far and had been doing this until I fitted the two new items. It's been fine for a couple of months, hoping one of them has not died as new GM too..

Any ideas?

[daveb948576]

have you tried the paper clip test?

maybe some new plugs and a bmw

[Grim Reaper]

have you tried the paper clip test?

maybe some new plugs and a bmw

paper test clip wont work as the light has to be on for more than 30 seconds for it to work...i thought its fine for the light to stay on for a few seconds then bugger off??? im sure my mk3 does that too but thats just the rag toy and get driven into the ground everytime i start it

[jtypecav]

Lol thanks for the advice guys, although the bmw comment went over my head(!) She ran near as dammit 245 bhp on the rollers with consistent torque of 210-230 lbft.

The manifolds have changed the car completely, happy chap now.