I'll try and keep it short, basically my battery in my gen 2 went bad almost 4 years ago, I bought a gen 3 and less than a year later had a gen 3 battery for my gen 2... After I put the battery in the other day(finally got to it) it started but was missing, put fresh plugs in it, added fuel system cleaner and filled the tank with fresh gas (had 1 bar of old fuel in it still) now it runs and drives. I can floor it with the brakes on and quick charge the battery but if I try and accelerate too much or try going over 55-60mph it starts missing in higher rpm. Bad coil? Dirty injector? The maintenance and check engine lights are steady on, my obd dongle is having trouble connecting so I haven't had a chance to check codes, I know that would help, just hoping someone with experience will know if I'm looking in the right direction. Don't have the tools and space to work like I used to...
More than likely clogged fuel filter, which is part of the fuel pump. I would try a high concentration of fuel injection cleaner and give it another tank of gas to work it's magic. That stuff will bust loose a lot of varnish and contaminates, so you may end up replacing the fuel pump anyways; but at least you'll have a cleaner fuel system when your do it. This could also be ignition coils, the electrons gotten lazy and the field can't build up fast enough to discharge and fire the spark plugs. Happy hunting........
Exact same symptoms on my bmw z3. It was the fuel filter. Luckily on that car, it is separate and mounted under the car.
I'm pretty sure that car could go faster than 55-60mph when it rolled out of the factory. I'm assuming you recognize a transmission slip, if you've ever encountered one or an engine over-reving, but traveling slower than it should?
I just meant in the way it's a controlled cut. It seems to hit a certain RPM, cut out, then resume without missing a beat when I let off the throttle a touch and revs come down. I thought a reduced fuel flow would cause more progressive stumbling near the limit, or problems at low RPM and high throttle, although I suppose the electronic throttle makes it harder to identify this type of thing. I REALLY need to get a working obd dongle!!!
