I recently replaced my "test" pipes with a used set of stock catalytic converters. Since then I've noticed 2 new sounds;
1. At cold start, it pops once like a backfire as soon as I turn it over. After that, it runs like a champ. This, I assumed, had something to do with the cats.
2. With car parked and in neutral, if I hold the throttle steady between at 2100 and 2400 rpm there's a noticeable deep knocking sound coming from the engine bay.
I don't feel it or hear it when accelerating, only when there's no load on the engine. Every time I drag my wife out to hold down the accelerator, we can't seem to replicate it. She's getting pissed.
My remedy so far has been to rip through and stay above the troubled RPM range, but don't know how long I can keep it up :smile:
I have aftermarket headers and exhaust, and a Dinan chip, and the oil is topped off.
Any commentary would be greatly appreciated.
1. At cold start, it pops once like a backfire as soon as I turn it over. After that, it runs like a champ. This, I assumed, had something to do with the cats.
2. With car parked and in neutral, if I hold the throttle steady between at 2100 and 2400 rpm there's a noticeable deep knocking sound coming from the engine bay.
I don't feel it or hear it when accelerating, only when there's no load on the engine. Every time I drag my wife out to hold down the accelerator, we can't seem to replicate it. She's getting pissed.
My remedy so far has been to rip through and stay above the troubled RPM range, but don't know how long I can keep it up :smile:
I have aftermarket headers and exhaust, and a Dinan chip, and the oil is topped off.
Any commentary would be greatly appreciated.