Car sounds lumpy - Advice please...

Hi All, Picked up my car at the weekend after having a full new exhaust including 200 cell cat. Only driven it home 40 odd cross country miles, it drove and sounded like a dream, very addictive. Not driven it again until today and it just sounded lumpy, best way to describe it, it sounds like an old VW beetle, and feels sluggish. Had to drive it on a 200 mile cross country trip to plenty of places to open it up and warm up. Occasionally it sounded good, but largely just lumpy. It sounds fine on iddle and revving standing. Before I go back to Topgear, just want to make sure there's nothing else it could be, or something simple I should do. Anyone else experienced this? Thanks in advance......

Does it just sound lumpy or is it lumpy? If it's misfiring then that's a separate fault affecting the sound. If it's smooth and firing on all cylinders but just sounds a bit poop, then yep thats the new stuff for you. After seeing and hearing my mates with all the combos of TG stuff I quickly decided it's not for me. It's ok budget stuff but they just don't put enough effort into tuning the sound. Their service is good though so I'm sure they'll try some options for you. Good luck. :thumb:

Difficult to define, very rarely it's smooth. Sounds lumpy and drives as if there's something restricting it.

Maybe a coincidental fault, such as Coils? Or maybe the new cats causing the ECU to change the engine settings incorrectly?

Perhaps a sound clip would be helpfull .. Im thinking possible misfire atm to be honest .

Sounds like a coil pack/ coil pack connector could of been disturbed.

:yes:

Thanks deMort, I'll try and post one up shortly. I'm taking in to my local mechanic for a few bits, including: window regulator; change over seat belts. I might get him to replace the maf sensor and coil pack. When the new exhaust was fitted, it had a new lamb sensor could that be it?

First off .. dont throw parts at the car .. i do hate people doing that .. it costs money ! Its possible the car is actually adapting to the new exhaust .. Basically the car trys to maintain Lambda on each cyl .. (correct fuel / air ratio ) .. it takes a while to do this when new parts or fault codes have been cleared . Its basically the car adapting to worn components and is normal . You need in the region of 50 miles to get sensible adaptions and to know if there is actually a fault .. with a tester then a bit quicker as you can see the engine values and fault codes that might not generate an eml on . For my part .. and as ive said im not a mod guy then the car will need to adapt and possibly even be mapped to get the best from the exhaust. Porsche have a set map in the DME for the Set exhaust .. you have changed this so the flow characteristics have changed and may well need a remap to get it correct .. ask Top gear there as this isnt my area of expertise im afraid .. i do standard stuff . EDIT .. A new Lambda sensor one side but not the other will often throw up an ageing fault with the one that hasnt been changed .. i always recomend replaceing in pairs .

Thanks as always deMort. It's a mod out of necessity, needed a whole new exhaust and oem prices were crazy. I've done 250 miles now with no improvement, so will get a diagnostic done. Good idea possibly remap too.

+1 on the diagnostic check before going down the remap route. I've just had a full system put on my 997.1 C4S and have put over 500 miles on it without any problems. I think kas750's suggestion is looking pretty likely. Hope you're sorted soon and able to get back to enjoying the sound which, imho, is far from 'poop'.....but each to their own. :thumb:

I had an almost identical problem with my top gear exhaust however it was intermittent which was even more annoying. I was really unhappy with it. Turns out it was blowing in certain circumstances despite me using all of the new gaskets, fittings etc. I replaced all of the gaskets and clamps with new Porsche ones and made sure it was well sealed. Problem solved now - unfortunately at the cost of the Top Gear exhausts, I think it has to be expected that there are certain corners cut. I'm happy enough with it now. Would I buy it again - probably not but I do however think its fairly good value for money.

Can the OP please change the title of this thread to remove the reference to Top Gear? The likelihood of the fault being down to the exhaust is very low indeed. I know, because I have one, and I have a lumpy idle that I'm pretty confident is down to a lazy lifter. There are any number of things it could be on the OP's car and when reading the thread title, people will infer the problem is caued by the exhaust, when it won't be, and Top Gear's good name will have been tarnished unfairly. By all means change the title back once you've proven the fault lies with the TG exhaust and not your car.

:thumb: That's a fair point.

Fair comment, have amended for now until I've had time to investigate....