88irocz28

I get horrible popping sounds from the exhaust when decelerating. I can't stand it. I got a new Flowmaster just weeks ago but it didn't cure the popping sound. You know that horrible snap, crackle, pop sound that plagues vehicles with wasted mufflers?

My Jeep used to have the same problem, but I cured it partially with a new exhaust tip, and later a complete new 2.5" exhaust.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

88irocz28

Come on man, somebody help me out here!

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

Fat Elvis Z-28

I might be way off, but if your valves are too tight or are worn and leakeng the motor will pop in the exhaust during back off.
Compression test??

deadbird

From what I've been -told-,, it's caused from running rich and a bit of off timing,, the overly rich exhaust on deceleration is actually burning in your pipes causeing the rice krispies in your exhaust.
another note,,,some people try to get that sound cause they like it,, to each thier own

My bird started doing that after I hollowed out my converter,,,

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<A HREF="http://anzwers.org/free/gta" TARGET=_blank>87 Firebird
84 Camaro</A>

- intelligence is learned, ignorance is universal

88irocz28

You mean timing is too advanced or too retarded?

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

deadbird

To be honest,,,I don't know,, I never asked,,,the sound never bother me enought o change anything,, sorry

Just a guess ,, I wouldn't think to advanced would cause it.

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<A HREF="http://anzwers.org/free/gta" TARGET=_blank>87 Firebird
84 Camaro</A>
Virtual Racing

- intelligence is learned, ignorance is universal

TRAXION

This is sometimes caused by a hollowed out converter. I get the same thing if I hold it in 2nd and drive at 4000rpms and then let off the gas. I'm not running rich and my timing is right on. It's my hollowed out converters.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

RP1987GTA

me thinks you got too much air in the exhaust at closed throttle.....probably caused by a problem in air smog pump controls.Too much air in the exhaust causes the unburnt fuel in the exhaust to ignite...causing the popping you hear

RP1987GTA

i just noticed you are using a 160 thermosate....this maybe causing the stock chip to keep you in openloop=air is injected into the exhaust manifolds=POPPING

88irocz28

Fall is here so I guess I'll have to switch to a 180* stat anyway. Let's see if that cures the problem.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

89IROCZ

The popping and cracking that you describe can be from lack of back pressure.... doesn't sound like thats your problem though.

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1989 IROC-Z
350c.i. TPI
rebuilt 700R4 with shift kit
3'' Monza Pacesetter cat back exhaust (minus the muffler)[SOUNDS OF THIS ON MY WEBPAGE]
new dual cats
3.23 Posi rear
hypertech chip
under drive pulleys
adjustable fuel pressure regulator
K&N Air Filters
Excalibur alarm, keyless entry and remote start
new:
struts, shocks, bearings, distributor, cap, rotor, alternator, battery, regulator
245 ZR16 50 Tires, Rotors and brake pads all the way around

Go to my webpage to find out more about it.
You can also see pictures, and hear sounds as well.
http://go.to/iroc-z

AOL IMer: JRShotliff

88'camaro305TBI

iTrader: (2)

I've heard that it is caused by uneven exhaust. For example, if you have a 2.5 inch hollowed out cat, and than going to a 3" cat back system would cause this problem. Try putting a 3" pipe to your cat back system instead of the 2.5" hollowed out cat and just put the heat shield around the pipe so it still looks like you got a cat there. I still have this popping problem also, but will be putting headers and 3" y-pipe on soon.

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Mods:Hooker Aerochamber 3" exhaust, gutted kitty,
March 2 piece underdrive pullies, smog pump gone,;these two made a very noticable difference.
14x4 K&N open air element filter-the best mod so far
Eibach springs with KYB's all around.
Appearance: Harwood cowl hood, Z-28 wing, painted black(7/20/00)-original color was light blue
*All these mods were made this year
Stock Options:117,000 miles on motor, 5spd, TBI, 305, T-tops
Run a best of 16.7 @85mph with traction problem. Have to try again sometime.

Vortex_89rs

Also remember, on deceleration, you are creating an even greater vacuum in your combustion chamber, and this leads to popping noises and other things that sound different.
Vman

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1989 Camaro RS
2.8 V6
K&N's
700R4 tranny
Cragar Street Pro rims (old Series 30)
Pioneer DEH-P3000

88irocz28

Will turned down exhaust tips do anything to cure the problem?

Could it be caused my an exhaust leak before the muffler? My exhaust manifolds sound like they are leaking when the motor is cold.

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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

tesla042

Mine pops too.. But it sounds kinda cool..

I have no cat, and no smog pump.. I'm not saying that these items couldn't cause it--i just mean that it still happens without them..

i DO have a sudden exhaust pipe increase... The stock 2.25" (i think) pre-cat exhaust flares up into my 3" catback where the cat used to live... but I don't see how that would cause it..

I also do have an exhaust leak somewhere up front... you can really hear it upon accel, but can't hear it other times... I don't think this is it either.

Haven't checked the timing or richness... Who knows... but it sounds cool..

90Iroc

Mine pops from gutted cats as well. I too, like the sound.

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"Clear your mind, relax, and float downstream."

RED82TA5.7L

I have a 1982 T/A with a Cross-Fire Injected 5.7l V8 with headers and a glasspack. I had the same problem with that cracking sound and my bolts from the header to the y pipe were loose. and when i decelerated it popped really bad. Then i tightened those bolts and it went away. but i really liked it. oh well. the best advice i can give you is try to tighten all exhaust bolts

RED82TA5.7L

1982 Pontiac Trans Am
Cross-Fire Injected 5.7l V8
Eldebrock Headers, 1 Glasspack right after
the cat.
Mods: 1.6 Proform Roller Rockers, electric
fan.

88poncho

One reason why cars pop is back presure. I had that problem with open full length 1 3/4 hooker headers. I added a 4" collecter extension with a turndown & that took care of it. I also picked up 2 mph.

Z28 Boy

as far as i know, any car will do that if the exhaust system is "free" enough...its just from no backpressure, thats all. i really dont think its anything to worry about.

my friend has a 98 s10 with a brand new cat that does it too (a LOT), so i dont think it has anything to do with cats.

-brian

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1991 Camaro RS
----------------------------------------------
Ultra Blue Metallic, T-Tops, ASCD Cowl Induction Hood

GM 350 HO Crate Engine - Vortec Heads, Edelbrock Performer Vortec Intake, Holley 670 CFM Throttle Body, Open Air Cleaner w/14"x3" K&N, Edelbrock TES Headers, Edelbrock Victor Series Water Pump, Accell Superstock Wires, Cap, and Rotor, MSD Blaster Coil, Hypertech Fan Switch & Thermomaster Chip, AC Delco Rapidfires, 3" Cat Back, Flowmaster 40 Series Muffler

700R4 - 2,400 Stall Converter, Vette Servo, Shift Kit, B&M Transcooler

Brian's 1991 RS

Central NY F-Body Association

88irocz28

I'm pretty sure it's due to uneven pipe sizes. GM gave these cars the crappiest exhaust they could. There's a 3" pipe going into the cat, from where it exits as a 2.5", squeezes into something that fits inside the 2.5" neck. at the rear axle the pipe opens up again into a 2.5" pipe, goes into the flowmaster and extis from there as 2.25" dual outlets. Crap, it sound like a total POS.

------------------
'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler

JAY87GTA

Mine does the same and it's not from uneven pipes. I've got 2 1/2" collectors that feed a 3" y pipe and it still pops some. I've been told that Dynomax mufflers will all but eliminate the popping noises. I just live with it, because trying to increase performance does have its compromises. Later

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'87GTA w/ SLP Cold Air, MSD Coil, Airfoil, Gutted MAF, AFPR, TES Headers, HI-FLOW CAT, Flowmaster Catback, Energy Suspension Master Bushing Kit

FastBroker

Get rid of that 160 deg thermostat, man. Does more harm than good by not letting parts expand to proper size(s). Use a 180 high-flow version.

By the way, poing coming from lean exhaust. Can richen the VE table in PROM at 20 MAP to reduce it. VE is low (ie: lean) there for mileage/emmissions concerns only...

[This message has been edited by FastBroker (edited October 06, 2000).]

RED82TA5.7L

why cant you listen to me?. just try it. i had the same problem. it was the header to y-pipe BOLTS. just try to tighten all exhaust bolts and tell me what happens. Thanks

RED82TA5.7L

1982 Pontiac Trans Am
Cross-Fire Injected 5.7l V8
Eldebrock Headers, 1 Glasspack right after the cat and dumps out before the rear axle.
Mods: 1.6 Proform Roller Rockers, electric
fan.

88irocz28

Copy that. I'll do it when I get under the car. I have to change my transmission mount anyway.

------------------
'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler