So, when I rev up the motor, doesn't matter what rpm I hit, as it's about to settle down at idle speed there's a sort of sputtering sound coming from the engine. And as soon as it starts idling again it's fine no noise. It's not a pronounced thud or knocking noise, and it's really hard to explain but a sputter is the best I can do. Also the engine shakes a bit whenever the noise comes out, then after that it's fine again.

 

mine always does this but there isnt anything wrong with my cars so its probably nothing

 

mods? probably just a little misfire.

 

As far as mods go I have had nothing too heavy done to it.

Engine was rebuilt with Turbo housings which were ported and side and mid irons were ported as well. All smog related items have been removed. Cleaned the throttle body of some of that "junk" on there. And that's about it.

I was guessing it was a little bit of a misfire, but I'm wondering will it do any damage in the long run? Is this a common thing (cause it seems I'm not the only one with the problem "turboIIrotary")?

I've looked for small vacuum leaks, none. Timing has been check and rechecked. So yea, all in all it's just bothering me a little bit, and if it's really nothing to worry about then I'll just turn up the music so as to drown out the noise.

 

little backfires??

mine does something like that...whenever im getting off the throttle i get little pops out of the exhaust...my cars perfect it just does it anyways....is that what your talking about or am i misunderstanding?

 

No it's not a backfire, it's actually causing the engine to misfire a little. I'll try to get a video up cause it's really hard to describe the sound.

 

Maybe?

 

does it sound like metal popcorn?

 

It's not detonation, you would definitely be able to tell that... it's not a little sputter. If you have all your smog stuff removed, cats, air pump... etc.... just straight pipes, then a little sputtering is going to happen at startup and at idle and you are going to backfire when you let off the throttle sometimes. I don't think it will cause any serious damage at all. Mine does it, and it's running great (except for the few parts I need to replace....) In fact, I kinda like how it sounds.

 

I have a similar problem.

As soon as I hit the clutch in to coast, it makes like a metal popcorn sound combined with like an insect buzzing noise. It seems when I put it in neutral, the sound stops for the most part.

 

Yea! Kind of like a popcorn sound is actually a better description than sputtering.

All in all I guess I was just being a bit paranoid. Thanks for the info guys!

 

so then i was right to begin with?

 

so then what are you relating this "metal popcorn" sound to? sputtering and popcorn popping i guess could be the same sound.....