I have owned my N/A R34 4 door for approximately 11 months now and in the past 1 month I have seen a significant change in how my car is running.
I have noticed that when completely letting go of my accelerator on a flat road, the car begins to brake quite quickly without any coasting sensation you would expect.
Even when going down a hill, (for those of you on the north shore in Sydney, the big dipper on the F3 near Mount Colah) I need to have my foot on the accelerator to keep it from dropping below 110km/h (whilst having momentum GOING DOWN A STEEP HILL)
The only modifications which have been made over this time period (and or 2 months before noticing a problem) was the installation of a 2.5" catback exhaust, and replacement of coilpacks and spark plugs.
It is obviously a very uncomfortable feeling and uneconomic when my foot needs to be left on the accelerator when otherwise, I could simply have the foot off and be coasting. In the meantime I have been shifting to neutral (I should have noted the transmission is tiptronic) to attempt to save fuel.
The uncomfortable and annoying "self-braking-problem" seems to be due to the revs not dropping instantly when taking the foot off my accelerator, it will instead drop from whatever revs i was on to 2k slowly creep down from 2k - 1.1k and feel asif a great load is on the gear. When changing to neutral immediately after letting off the accelerator, the revs drop to ~1.1k, 1k and obviously not being in gear, I can coast comfortably.
the only reason I am posting is because I know that my car was performing differently with the ability to simply coast, without going from 60km-40km in 2 seconds on flat road and momentum.
I would REALLY appreciate any insight or help into what the problem may be!
lack of backpressure to the engine?
limp mode for some reason?