Strange Sound When Starting
 

I thought I saw something on this a long time ago, but I can't find it now. Sometimes when I start my car I hear this strange sound sort of like an air valve being released when I turn the ignition. It doesn't do this all the time, and it doesn't seem to cause any issues. Its coming from the engine bay, and it but I have no clue what it is. The is much larger since I installed the new pump and injectors, but I don't know if thats perception or reality.

Just so its all clear I did several searches, but I didn't find anything directly related.

Injector priming?

Ok, so does that imply a leak if it sounds louder than it had been? I don't smell or see fuel, and I did when I had fuel rail issues.

Not necessarily. That last post was assuming you are running megasquirt, which can be setup to fire a priming pulse when you turn the key to ignition ON. At least the PNP model does that. If so you could always turn off the injector prime pulse in Megatune to see if that's they noise you're hearing.

I am running a MSPNP. If this isn't and issue I can leave things as they are. I just wasn't sure if it was causing a problem or not.

same here, priming pulse being fired 2 seconds after ignition is turned on. It's barely audible over the fuelpump whirring tho..

Sounds like he's got The Pop. (Priming pulse is more of a quiet click.)

This is not quiet at all, its pretty loud, I would bet you could hear it from out side the car several feet away if things were quiet. This doesn't happen all the time, only every once in a while. It might even be when I haven't driven the car in a couple of days.

"The Pop" for sure.

The ms sparks the spark plugs when the key is turned on and it is igniting some residual fuel in the cylinder/intake mani.

Is that a bad thing, could it be similar to preigintion type explosions?

Its nothing to worry about.

search for the forum, There is also a FAQ about how to fix it.......

Cool, I'm on it.

It's a sticky: https://www.miataturbo.net/forum/t33964/

Thanks Joe.