So when I sit at a light, my idle sounds like farts. It pops and rumbles, but the tach does not move. Under acceleration, I get no noises except beautiful rotary music. I have good compression, and all 6 seals are o.k. I am wondering if this is because I have gutted cats? It never did this before I gutted the main cat. Any ideas?

 

Yeah, thats what you hear when you have gutted cats. Have Fun....


Brandon

 

It sounds pretty cool on my friends GXL, different than a down/midpipe like mine.

 

Good. I am getting a header and presilencer soon, so no more farts! Thanks guys!

 

on that subject?? how come our cars backfire when shifting over 7000?? can anyone explain this?? i hear its because we run a lil rich?

 

i have bone stock n/a 87 rx-7
i get idle farts with no mods whatsoever...

 

Its small backfires. It happens when you dont have cats, b/c most cars run rich at idle.

 

I DO HAVE CATS.... ALMOST STOCK 91 NA

 

RX7's run rich at idle, and it backfires. Sometimes cars with cats do it, almost always cars without do it. It doesnt mean somethings wrong, and theres nothign you can do about it except lean out the idle with a S-afc or something.

 

My 87 with a CATCO system does the same thing...pretty badly too till it gets good and warm.

 

Well I dont know guys. It could have something to do with rich or TPS or other things. I noticed it in my 89GXL and went to the rotory shop down here. The guy told me he can fix it for around 380 pluss labor abour 480 bucks , but he also told me that it wont hurt the car for the life of it. It just might get anoying. So he wasnt riping me or anything. He told me it had something to do with the idle air control valve causing a LEAN misfire.
I still dont know what he meant exactly, but I have reduced my pops and are almost completly gone with my streight pipes. I think the rest of the pops are just from a slightly rich condition but it goes away under 1000 rpm when warming up. I think I fixed it when I took my ACV pump actuators rods sleeves out. Im going to work on the EGR and BAC next so im sure I will have a better idle.

 

It's called Afterburn... Search the archives for related discussions using this keyword, should turn up dozens of hits.

 

I would like more info on the tremendously loud backfires, you know the one that sounds like a gunshot (especially in a tunnel), I get when shifting at high RPM. I assume it is a rich condition, but this makes no sense b/c I have an unmodded NA. I have noticed that I rarely get better than 12.5 MPG (fairly aggressive "city" driving). I got ~22MPG on the highway.

 

are those farts that don't do anything??

 

WOW! this guy is a newbie, but is the SMARTEST one I have ever seen, he knew to search and eveyrhitng (most newbies repost the lamest questions because they aer too lazy to search) I commend you sir