[N0DIH]

My Cad (91 4.9 Dev) has an interesting, although scary problem.

When you are in neutral or park, doesn't matter, although more prevalent in Park, and you rev the engine, all of a sudden BANG! it sounds like you just revved into the parking pawl (that tone, like when you put it in park and let the car roll into the pawl). The engine torques up when that happens. It is taking a lot of power when it does it. The bang sounds like someone just hit the engine/trans with a 20 lb sledge hammer, HARD. It will scare the crap out of you.

It strikes me as coming from around the chain belt for the transaxle, but it is hard to tell. All it takes is rev it up to around 1000-1500 and it will do it randomly, only once, and I guarentee you will take your foot off the gas!!!

Is the chain slack and whipping or catching on itself? Is the parking pawl loose?

It never does it driving. Only while you parked or in N and revving it, when you are working on it.

No, I don't practice doing it, but obviously it isn't a good thing.

Thanks!
Tom