Speedster SC, eratic idle, lack of power & knocking sound. Help!

[pindone]

please delete this post

 

[incognito2428]

I am not sure about the knocking but as far the fluctuations in rpms at idle that is normal.

 

[JFizzleJR]

If you have an extra set of fuel injectors I would recommend swapping them out to test for a failed injector. That would cause a popping noise around the 4000 RPM mark. If you don't have a spare set, used ones are available for $15-$30 every day of the week.