Berk HFC frontpipe mpg issues

[Dazwash 2]

I've just recently installed a Berk high flow catted frontpipe and my mpg has gone through the floor.

I can watch the needle move when I am gunning the car it's that bad, whereas before on the stock frontpipe I saw no such increase in fuel consumption. Is this normal?

I noticed an increased eagerness to rev, but I don't think it's worth it if I'm going to need to be refuelling every 5 minutes. Plus there's a hell of a lot of resonance that I wasn't expecting based on what I've read online. I have a resonated Scorpion cat back for reference and the manifold and overpipe are stock.

Anyone else have similar experience, or should I be concerned that something else is wrong with the car and the frontpipe is just a coincidence?

[Luke 193]

Interesting. I have also recently installed a Berk HFC and noticed my mpg go up since fitting it over a broken oem cat. The noise is louder and deeper because the stock resonator is removed with the Berk. These cars are very raspy by nature, you should look to get a Helmholtz resonator welded into the car back exhaust at some point to keep the noise, drone and resonance levels down. 
 

As for the mpg going down, you should look to have the ecu remapped to match the exhaust mods. This will sort out the fuelling and increase your mpg. I would suggest removing the negative battery terminal for 30mins to allow the fuel trims to reset as it might improve your mpg. 

[Dazwash 2]

Thanks for the advice, I'm going to test running the stock frontpipe on the car again and see if I can eliminate that from the equation. I may have made a mistake in buying the frontpipe, in which case it may be up for sale on this forum soon.

[Dazwash 2]

Tried the old stock frontpipe and found the source of the leak. My catback was loose at one of the joins, that may have been what was causing all the noise as the leak was before the resonator. Likely getting some sound leaking prior to resonation with the Berk pipe. Happy to have found the issue.

[Luke 193]

Glad you found the cause of the issue. Did you replace the donut gasket from cat to cat back? It’s a crush seal so could be the cause. 

[Dazwash 2]

No the doughnut gasket was fine, I made sure to reuse that. It's the Scorpion exhaust. It is connected by slip joints and the front joint ahead of the resonator is leaking. Going under the car later to try and adjust it. It could have been the cause of the sound from the Berk, so may end up putting that back on at some point.

 

[Dazwash 2]

By the way, does anyone know where I can get a replacement Cone/Doughnut gasket for future reference? I've checked eBay, but not 100% sure about the sizing or part number. Any help much appreciated, thanks.

[sxocpaul 49]

https://www.ebay.co.uk/itm/184486671652?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=dDRkETdmTTi&sssrc=2349624&ssuid=4JvZ2Qu_TyW&var=&widget_ver=artemis&media=COPY

[Dazwash 2]

That's perfect, thank you!

[Dazwash 2]

Another update, after installing all of the new consumables, gasket, properly sealed slip joints and new spring bolts. Night and day, the Berk pipe sounds fantastic paired with the Scorpion resonated catback. Love it. Thanks for all the help on here.

Only issue I have is that I just couldn't get one of the spring bolts onto the frontpipe/catback around the Doughnut gasket. I ended up removing the spring, so I only have one bolt with the spring there. Meaning to get it done properly when I have more time, but any tips on compressing the spring to get the nut on the bolt? I almost did it twice but the nut pinged off as soon as I released the pressure slightly.

[Luke 193]

I had similar issues sorting this before. From memory one side goes easy then the other, I think one points more towards the transmission tunnel and that one I usually do up loosely first. Then you can get the other spring bolt in before buttoning both of them down. One is always tighter then the other. 
I’ve not seen the joint that the Scorpion uses but when I fitted a Tuning Developments exhaust I had to get some longer bolts and penny washers from B&Q instead. 
 

 

[Dazwash 2]

Glad to hear I'm not the only one with the issue! Thanks for the info, did you use the penny washers to hold the spring in place with the longer bolt? Looks like that would be a good route to take, as it is really difficult getting the standard bolt and spring on. Thanks

[McDude 40]

Has it resolved your MPG issues though?

If you have a new cat with different airflows this will upset your closed loop control as the lambda sensor will be in a slightly different position and see different velocity over it and possibly different gas presentation. A leak would exacerbate this error state and maybe sorting the leak sorts out your closed loop as well. If you are hosing fuel you'll be running rich as hell, so get it sorted not just for your wallet, but also because it will hurt you big time with possible fouled plugs, fuel in oil and damaged cats if you run that way for a long time - of course this will really hurt your wallet!!!

[Dazwash 2]

Yeah, the mpg issues seem to have settled back down now, I'd say it's marginally better than stock. So that's a bonus, just the leak to sort now at the doughnut. My wallet is in enough pain as it is 😂

[Luke 193]

Yes penny washers with the original springs and longer bolts will give you more wiggle room to get it sealed up. 

[Dazwash 2]

Finally got to the bottom of this issue come MOT, and it was actually a leak in the cat back exhaust. My scorpion resonated cat back had split around the resonated section. I'd assumed it was my own dodgy DIY but my work on the car had nothing to do with it.

Scorpion were great about it and sent out a new part, so that was bolted on and passed MOT no fuss. Can't fault them for their service.

MPG issues are gone now too, surprisingly.