avoid

after I start her up I get this poping from the exhaust is that mis-fire??? my main cat is shot so I get the smoke that goes away but it smells like gas is this normal for a burned up cat??? sorry for all the noob q's but Im a noob to rex's

afro thunder

when i had hollowed out cats, it backfired when you let off the gas, more at higher RPM's.

Cory Simpson

The popping in the exhaut is called afterburn, and is do to:
1 Incorrect ignition timing
2 Leaking intake air system
3 Malfuntioning electronic spark advance
4 Incorrect idle speed
5 Defective TPS, or fuel system pressure sensor
6 Defective ACV (Air control Valve), or AAV (anti-afteburn valve)
7 Malfuntioning BACV (bypass air control valve)
8 Leaking or faulty injectors
9 Faulty AFM (Air flow meter), or intake air tempeture sensor
10 Incorrect fuel pressure
11 Defective EGR valve
12 Bad compression

And I am not going to type how to fix each one of those, so go to an autoparts store and buy a Haynes manual, then look up afterburn in the trouble shooting section and go from there. And you cat wouldn't cause that, and also it sounds to me like the afterburn is caused in your case by leaking fuel injector, and that would explain the smoke on start up that goes away after it has warmed up. So it will most likely fix the problem it you take the injectors out and have them cleaned. And if you take them out your self you can send them to RC engeneering, they will clean and test every injector separtly.

Castrol86GXL

quoting the haynes manual i see (i was going to do the same)

rotary>piston

does it pop after warming up? If not then I wouldn't worry about it. Every RX-7 I've been in misfires a little when warming up. Old parts don't work quite as well as they used to.
In most cases I think it's just an old bac. I know my BAC sucks ***.

Cory Simpson

Yup




I'm telling you it's leaky fuel injectors, he said, "I get the smoke that goes away" seeing as he has smoke on start up it is probably because of the leaky fuel injectors which is also causeing the afterburn. But it also probably is a combination of more than one thing that is causing it to.

rotary>piston

injectors are probably part of it too. You're lucky that they aren't bad enough to flood the engine yet.

avoid

how can I tell if my injectors are leaking???

Cory Simpson

Well, you really just have to check the sytoms, and seeing as you car is around 16 years old or so. They need cleaned anyways, it cost me $100 bucks to have mine fully serviced, cleaned, and rebuild. So it would be wise to have them cleaned whether it fixes the problem or not since it is also dragging down your fuel exicence if they are leaking, clogged, or dirty. But it sounds like leaky fuel injects is the biggest part of the problem. I don't know of any real way to test, but maybe someone else does, Sorry

mac_dad6

this is actually an rx-7 trademark. to some extent it is caused by blowby due to the design of the exhaust ports in the rotary engine. it is more noticeable since your cat is gone. that could aslo cause your fuel smell. if it doesn't cause your car to run badly i wouldn't really worry about it. i would however have your injectors cleaned like corey simpson said

slow87turbo

hehe the poping is flames....i love it when my TII does that. whewn it did it at first i had thought something was falling off the car. but its cool.


ej

slow87turbo

hehe the poping is flames....i love it when my TII does that. whewn it did it at first i had thought something was falling off the car. but its cool.


ej

Madrx7racer

Flames rock!! My TII does it too, but i have to check the oil often pushing the car to high RPM's makes it loose oil...Keep your eye on it.

amused

i was under the assumption that those little coughs/pops/etc etc were normal..

btw, these are not the FLAME pops. he's talking about something totally different.

SonicRaT

iTrader: (6)

I agree, this is pretty normal for rx7's. Everyone I own does this, usually only when cold, but it'll do it a fair ammount when warm, also the upon deccelerating.

avoid

thanx I feel better now that I know others do it too

Cory Simpson

Mine does it so bad that I think that it is going to rattle the mufflers off, they just sit there and shape.