i had the new engine put i and the cat gutted and nowwhen i shift or come of the gas i get an explosion or popping coming out of the exhaust. what's the problem and how do i fix it?

 

 

Which cat did you gut? The pre-cat or the main cat?

If it's the pre-cat, then you'll notice the backfires a lot more. It's normal depending on the amount of backfires you are hearing.

 

it was the precat, anyway to correct it though?it's really annoying

 

meow

 

Buy a new pre-cat and don't gut it.

 

sounds expensive to get a new pre cat. theyre in the 1000 dollar range

 

Probably, and they aren't all that good for the car since they produce a lot of heat under the hood.

You might add an extra ground wire or two under the hood, that helped my car not backfire as much, but it's going to regardless once you remove or gut the pre-cat.

 

Anybody found that spot where you can make machine-gun backfires??? It started when I got my PFC, but at 2000 rpm when backing off the gas there's a particular throttle position just a hair before completely being off the throttle where it sounds like a tommy gun.......I like it! Good entertainment when you're cruising downtown or in a parking garage!!!

 

Yeah, I've found it, I always embarass my girlfriend with it when she is in mycar because people look at me like I drive a POS

As you decelerate it just goes..POP POp Pop pop pop pop!

HAHA

 

someone mentioned grounding the car under the hood. where would be the spots needed to do that to stop the problem?

 

Grounding won't completely stop it. There is no way to completely stop it unless you put a non-gutted pre-cat on the car.

However, grounding MAY help reduce it some (or you may be getting the normal amount of backfiring, just depends on your car).

Use some 10 gauge or thicker wire, and connect it from the negative terminal on the battery to the car chassis. Make sure both areas are clean to allow for good contact.

 

You might have an exhaust leak. All Rx7 stock exhaust do crack causing leaks, which cause the "popping sound" or

 

bad gaskets.

 

I always thought 'popping' in the exhaust was the result of a rich condition. The unburned fuel is exploding in the hot exhaust. Tom

 

ok, so it's probably running rich and the air fuel ratio is poor. I should also mention that i am getting a bucking at low rpms as well, but not low enough where the car should buck as it is. so WHERE DO I ADJUST THE AIR/ FUEL ratio? someone was telling me the tps throttle postion sensor might correct the problem of the bucking is that also the same air /fuel adjutment needed to correct the popping out of the exhaust?????

 

For work, I park on the 3rd floor of a parking garage - and I find that coasting downhill in gear when the engine is not fully hot will give me that pop pop pop sound.

I actually think it is kinda funny - you should see some of the people look. The sound of a modified exhaust and popping echoing in the garage structure - must scare the **** outta some peeps.

After the engine is fully warm, the popping decreases significantly and after 20/30 min driving, I rarely get any at all.

M

 

mine does the same popping. sometimes i get them after driving hard. i get big pops between high RPM shifts.

mike

 

New Plugs will also help reduce the afterburn popping -

 

i just changed my plugs and its almost worse

 

I went from a stock exhaust to a Kokamato racing one
I complety removed my cat.I now get really big back fires and some really good flames.
Its a real good deterent from people tail gating
lol

 

Rickmyster,

You need to do some serious research if you're just now realizing that the car is popping and want to "fix" it. Do you know what air/fuel mixture is? Do some research, a LOT of research before you blow your car up. Don't do any more "mods" to your car until you know what is going on inside your car.
These are the people who end up saying, "rotaries are fragile, and don't last..." Good luck to you.

Richard

PS- All sufficient knowledge is on this forum, do a search on air fuel mixture, popping, future mods, modification steps, etc...

 

"Better to run rich than lean"

 

94 7 w/ 19 k miles
--- have pfs downpipe & exhaust, k&N dropin, just replaced plugs & wires, added an 8 gauge monster cable to chasis & engine for ground, and still have significant backfire.

No way to tell if I am running too rich or not, but it is likely a given.

 

YEs...Running to rich will cause the car to back fire! I've have put new Magnacore 10mm wires and now my FD doesn't backfire that often...only when the car is very cool and I try to gun it is when the car is an AK-47. I agree with 93TTRX7 that running rich is better than running lean. I am wondering how we can lean out the car more?? Probably I will need to get my car re-tuned.