Hello, I have a question about my s4 convertible that has lost power due to only one rotor spinning. I did a compression check on the front and rear rotor and they're both 90 psi. So I tested whether there was spark on all the spark plugs. There is definitely spark going through all four spark plugs. One thing I do know is that my primary injectors are failing. Sometimes the car turns on and sometimes it doesn't due to flooding. The car starts but I know and I can feel that the rear rotor is not working. My only theory at this point is to change my coils. Does anyone else have an idea to what this issue might be? Can it be the injectors? Any helpful ideas would help.

 

1. Its impossible for only one rotor to spin, the only way yhat woukd happen is if your eshaft snapped, and if that happened, it wouldn't run/sound like metal in a washing machine

You have spark, so your coils are fine. Does it only do this when hot? Cold? All the time? And did you do the compression test hot motor or cold motor?

 

if you have compression on both chambers, and spark at all four plugs (assuming timing is good, too), then it would be behoove you to address the injectors - especially if you already suspect they're failing. have them cleaned and refurbished. clean the rest of the fuel system while they're gone. change the filter and see if your problem goes away.

 

I know the primary injectors are bad. The car has trouble starting whether its cold or hot. It floods so I have to disconnect the fuel pump, crank the engine over to get rid of the excess fuel and connect the fuel pump back. I did a compression check while the engine was cold. I ordered new injectors so if that doesn't take care of the problem then I don't know what the problem could be. One thing I do remember though is that every time the car got started every morning, I would have the same loss of power for like 20 seconds, then the car would backfire and the it would run normal.

 

Logic would suggest that if you have a known fueling issue your problems would LIKELY be starting there...

But that's just, like, my opinion... man.

 

this is a safe (and well advised) place to start. in the event that this doesn't solve your problem, you can cross that bridge when you get there. a tuneup won't hurt either.