I recently fitted a second-hand Milltek 4-2-1 system to my 1.7 Puma, it’s the full system and I had a sportcat custom made (200 cell) so that part is new. Since having it fitted I’ve noticed a strange issue. Everything runs fine on tickover and when accelerating (yes it’s slightly more powerful than before, which is what I expected) but when cruising, particularly noticeable on the motorway, there’s a very slight hesitance in the engine every 10 seconds or so. It’s quite hard to explain. On the motorway it’s as if you’re driving in to a gusty head wind, just every 10 seconds or so there’s a very slight dip in power just enough to make it noticeable. It’s also noticeable when allowing the car to come down on the revs - if I lift off and just let the revs comes down it’s not smooth any more like it used to be, there’s a dip every 10 seconds or so which makes the car lurch forward very very slightly. It’s really weird, it’s just not running as smoothly any more.
I also recently fitted a FRP mod’d airbox (but it ran quite happily just with that for a few weeks before fitting the milltek) and my ECU has also got Pumaspeed’s remap (DIVE ECU). So apart from the 4-2-1, FRP airbox and ECU, its standard!
I’m guessing the manifold has messed something up slightly, but no idea what??? Any suggestions? I’ve checked for anything obvious, all the pipes around the inlet & maf all look OK and the whole system was fitted by local (and much trusted) mechanic so I’m confident it’s all been done correctly. I also extended both lambdas but ran the car for several weeks with them extended before fitting the milltek and everything was fine. I’m happy with the extra oomph the system has released but not happy with this slightly rough running when just driving at normal speed / cruising.
I also recently fitted a FRP mod’d airbox (but it ran quite happily just with that for a few weeks before fitting the milltek) and my ECU has also got Pumaspeed’s remap (DIVE ECU). So apart from the 4-2-1, FRP airbox and ECU, its standard!
I’m guessing the manifold has messed something up slightly, but no idea what??? Any suggestions? I’ve checked for anything obvious, all the pipes around the inlet & maf all look OK and the whole system was fitted by local (and much trusted) mechanic so I’m confident it’s all been done correctly. I also extended both lambdas but ran the car for several weeks with them extended before fitting the milltek and everything was fine. I’m happy with the extra oomph the system has released but not happy with this slightly rough running when just driving at normal speed / cruising.