[MiniPetrolHead]

Hi there everyone,

Right, a mate of mine has an 04 MCS and has put on that ebay manifold with de cat, GTT re route pipe, pipercross pannel filter, alta V2 15% pulley and NGK iridium plugs.

With all that you would have thought the car would be quite fast...... well its DOG SLOW!!!! My old Mini One when it was running 135.4bhp would have put up a very good race!!!

I drove his car this after noon and my MCS feels soooooo much faster and all i have on there is atla pannel filter and the MiniMania exhaust manifold with a STANDARD pulley!!

How does this work? The first thing that sprung to mind was that it has not got enough back pressure, could this be the problem?

My friend and i are doing some decorating etc for his dad and he is buying 2 Scorpion exhausts for us both, would this solve the back pressure problem as it has 2 back boxes rather than just the re-routed 1 back box?

Advice please on what to do would be greatly apprieciated!

Alex

[minioneandrew]

Sounds like a bigger issue, rather than just to little exhaust back pressure. A dodgy Bypass valve maybe? A boost leak somewhere id imagine.

[Berthil]

What andrew says. Try to hook up a laptop which measures the boost pressure from the OBD and you'll know. I had a broken bypass valve and the boost pressure dropped above 4000 rpm.

[MiniPetrolHead]

Yeah just got of the phone to GTT and they say exactly that so im going to do 2 things, test the bypass valve, and also put a marker on the pulley and pulley shaft on the supercharger to see if it is slipping.

Thanks for the responses, i will let you know how we get on!

Alex

[MINI-Morgan]

Its forced induction so back pressure is very much less of an issue.

I'd go with what Berthil said and see what boost you are getting. Dont forget that the ECU values are absolute pressure so measure the pressure before you turn the engine on to find out how much air pressure there is beforehand. Otherwise you might be fooled into thinking you are running 30PSI instead of 15PSI And while you're there check the short and long term fuel trims and the O2 sensor output to see if you are running seriously lean or rich.

At a stab in the dark id say either boost leak or its over fuelling. Certainly hope its not under fuelling and pinking or you're going to loose a piston very soon!

[MINI-Morgan]

Quote: Originally Posted by MiniPetrolHead (original)

Yeah just got of the phone to GTT and they say exactly that so im going to do 2 things, test the bypass valve, and also put a marker on the pulley and pulley shaft on the supercharger to see if it is slipping.

Thanks for the responses, i will let you know how we get on!

Alex

Did you change the belt too when you did the pulley?

[MiniPetrolHead]

yeah the belt was done at the same time as the pulley so everything is new. its either the pulley is slipping of the bypass valve is faulty.

Alex

[MINI-Morgan]

Good to hear! Hopefully thats a shorter belt too. I'd also check the intercooler seals too... very common to leak under increased boost pressure too. Only 4 bolts to check they are tight.

[MiniPetrolHead]

Thats also a good point, as the intercooler was changed for another standard intercooler as the old one had its blades flattened off by a pressure hose, so it may not be a good enough seal around the snoot boots. Cheers for that one mate, will give it ago!

Alex