So I ended up putting on a regular 40 series dump on my HEMI. And after about a week I noticed my rpms pulling down really bad once I come to a stop like it's trying to die then they shoot back up, So I took it to the shop and they had it for 3 days... and the only thing they thought was wrong is that the 40 series doesn't have enough air flow which is causing the rpms to pull. Is this true? I don't mind putting on a 50 series but I don't want to waste $200 on another muffler if that's not the problem. Thanks.

 

do you have a cai inthat thing yet . if not try it home made 50 bucks.

 

No I don't have one yet but wouldn't that make it worse? If it's already having problems the CAI is gonna pull more right?

 

1) Although it's been said to be true that FM's in general have as bad, if not worse flow than stock, I don't see this being your particular problem. Maybe you can try the TPS resetting procedure, found in the 3rd Gen FAQ section...

2) If you're paying $200 for a freakin muffler, you're bending over and walking in backwards going to that exhaust shop. Even if that's including install, RAPE! Thats close to the price for a whole catback

 

My 40 is fine no droppin in rpms at all i would look somewhere else other than the flow.

 

^ Do you have two FM's or just one?

 

I have one 40 series on my hemi. 130,000 miles. No problems with idle at all. It is true that flowmaster does not make a 40 series for the hemi and flowmaster themselves do not recommend you put it on the hemi because it doesnt flow good enough for the engine. Thats why they have their 50 series.

 

I've cleaned the TB and reset the TPS, the only thing I haven't done is check the PCV but the dealer said they checked it and it was fine. So I have no idea what to so.

 

did you try to reset the settings with a battey un hook?? leave the neg off for five minutes this forcesthe ecm too relearn the different settings it is facing

 

i cannot imagine any flowmaster flowing poorly enough to cause enough backpressure to cause that problem...