Exhaust question - Toyota Nation Forum : Toyota Car and Truck Forums

4Aaron GE · 08-05-2002, 05:15 PM

Here's something I've always wondered: What is that popping noise that cars with aftermarket exhausts make? Does the exhaust somehow screw with, say, the O2 sensor, and cause it to run rich or something? Or have those noises always been there, but were just filtered out by the muffler?

***EKam*** · 08-05-2002, 05:26 PM

I think that can contribute to anything.... for example Jeff had a bad cat so he had those poping noise...

But I would make a wild guess... is it because aftermarket exhaust allow the air to exit quicker therefore more air is allowed to go into the engine = rich?

bondobondo · 08-05-2002, 08:33 PM

arron, i think that popping noise is just there most of the time, esp on older cars,

it is just with an aftermarket exhaust (ala straight thru) the pop is more noticible.

DrtySthV6SE · 08-06-2002, 12:49 AM

i believe the popping noise happens while your exhaust piping, cat, and other things are cooling down after driving for a long distance. Yes it is more noitcible with an aftermarket or straight through exhaust.

I BELIEVE

wunderboy · 08-06-2002, 10:49 AM

the popping noise (when reving down) is caused by valves letting go. Now I am not 100% sure about how this happens but I believe it has to do with exaust gass's pushing on the valves when it doesnt all get out of the cylender. This could be wrong, but I know for sure the popping is due to valves and/or thier seals.

DrtySthV6SE · 08-06-2002, 10:59 PM

Are you talking about the popping that occurs after you cut the car off??

wunderboy · 08-07-2002, 09:27 AM

I think he is talking about the popping that occurs when you let off the gas, and are still in gear but letting the engine slow the car down.

Deep · 08-07-2002, 10:43 AM

Why would your valves make that noise?

Air is being pushed through the exhaust as you accelerate, this creates a wall of air that pushes through the system, when you downshift, the air is sped up at a rate much faster than before and breaks through that wall. Same effect as a jet breaking the sound barrier.

DaksGT · 08-07-2002, 10:48 AM

I made a tuff pop on the highway today.

wunderboy · 08-07-2002, 06:28 PM

Well to be honest. I don't know. But my friend is a class A mech, and we had an argument about it one day. So I immagine that its true.

I'll ask him.

***SCEPTER300RR*** · 08-08-2002, 02:50 AM

running rich and the unburned fuel is being kicked out... it is useful to upgrade ur ingition system to MSD, jacobs etc... that should cut it down but not completely... cos the ignition computers activate on a certain RPM only so for my MSD SCI it turns on around 3krpm so thats when i dont get the sound but anything under that when i engine brake it comes out..

humpty

fatredcircle · 08-08-2002, 05:12 PM

yeah..its your car running rich. should hear mine...its bad ass...hopefully 20 more degrees and i should get flames!!! its like lemans except ae86 style.

martingouda · 08-08-2002, 11:40 PM

imagin......an ae in lemans....ha h aha

that would be so pimp...sponsored by a tofu manufacturer