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Location:
Castle Hill
Registered:
August 2003
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4AC makes POP sound when not accelerating?
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Wed, 09 June 2004 11:17
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Hey, I am worried for my engine, its just a stock 4AC, with 370000Kms, and recently whenever I am just rolling along with my foot off the gas it makes a pop noise from the exhaust pipe every now and then. Not as loud as a backfire, but the same sort of noise, just quiter??? I had it all checked, serviced and tuned not even a week ago, at Kmart, it used to make the noise before this, but now it is more often.
Has anyone had this probelm, or know what is causing it so I can fix it?
Thanks muchly in adance.
-Whitchy-
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Location:
Sydney
Registered:
January 2004
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Location:
Adelaide
Registered:
January 2004
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Re: 4AC makes POP sound when not accelerating?
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Wed, 09 June 2004 13:36
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370000 kays?
just kill the thing and get a 4age! 
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Location:
Northgate, QLD
Registered:
July 2003
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Re: 4AC makes POP sound when not accelerating?
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Wed, 09 June 2004 23:56
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I've got the same thing with my corona at the moment,
I had it really bad when just idling but then got the fuel/air mixture adjusted and the timing checked, and now it doesn't really do it but only mainly when its hot and being running for quite some time.
My mechanic said he wants it back to just fuck around with it and to find whats the real cause so next week thats getting done, but he said it can range from a hose (in the intake section) with a crack or split in it, to dripping injectors, he said thats the least likely thing because the car goes so well off idle.
My tip would be to take it to a auto-electrician, after he did his thing, the car starts noticable better and idles a shit load better, plus he might be able to diagnose the problem.
[Updated on: Thu, 10 June 2004 00:00]
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Banned user
Location:
Liverpool NSW
Registered:
March 2004
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Re: 4AC makes POP sound when not accelerating?
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Thu, 10 June 2004 00:29
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i have a 4ac running 3 pistons, drinks much oil has fuel and the thing still going always reving its nuts out
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Thu, 10 June 2004 05:39
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...Which on 4ac, ain't too many revs...
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Location:
Victoria
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Thu, 10 June 2004 06:11
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Check for holes in your exhaust..
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Location:
Brisvegas
Registered:
June 2003
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Re: 4AC makes POP sound when not accelerating?
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Thu, 10 June 2004 06:50
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overfuelling?
have a play with the mixture screws...could help
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Registered:
May 2004
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Re: 4AC makes POP sound when not accelerating?
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Fri, 11 June 2004 00:16
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a bad o2 sensor can put too much fuel in the exhaust
like an exhaust leak
i assume that's wut the pop is
my 22re will pop at times with the hotter cam and o/s valves and opened up exhaust
why wouldn't any car with wide open throttle use ?
mixture goes down to like 12 to 1 ...
isn't that gonna put fumes in the pipes?
then you got that ultra hot catalyst it goes thru...
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Location:
Brisbane
Registered:
June 2004
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Re: 4AC makes POP sound when not accelerating?
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Sat, 12 June 2004 04:15
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When you're deccelerating you're on you idle circuits, if its popping it means you've got a bit of a lean idle or vacuum leak, its not really a problem, i quite like it actually ( the popping), but if you want to get rid of it you can richen up your idle mixture.
Other thing that causes it is if your timing is too retarded or a combination of your idle mixture and timing
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Location:
Brisbane
Registered:
June 2004
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Re: 4AC makes POP sound when not accelerating?
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Sat, 12 June 2004 04:17
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basically, all other things been equal...
pops or caused by leaning out
backfires or caused by overfuelling
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Location:
The Rainy City
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Sun, 13 June 2004 06:24
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if you are still in gear, rolling with foot off the accel, then that occasional muffled popping is overrun. Carbs work on vacuum, your engine is drawing in more petrol than is required (because no load but wheels are still turning the engine at the road speed) and the fuel is ignited in the hot exhaust. Nothing major. In fact i reckon overrun is the most appealing sound of a modified exhaust.. just listen to a V8 Supercar coasting into a corner for an example.
cheers
tom.
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: 4AC makes POP sound when not accelerating?
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Sun, 13 June 2004 06:38
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my 4ag crackles like a mofo on overrun
vrooommmmmmmm *bak* *bak* *bak* *bak* *bak*
hah
probably due to the hole in my exhaust tho
hohoho kinda cool though
sounds like a racecar.. hehe
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Location:
Baulko Hillo
Registered:
April 2004
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Re: 4AC makes POP sound when not accelerating?
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Sun, 13 June 2004 06:40
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How does it go again Garth??? 
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: 4AC makes POP sound when not accelerating?
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Sun, 13 June 2004 08:32
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it goesss.....
stfu! 
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Location:
melbourne
Registered:
June 2004
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Re: 4AC makes POP sound when not accelerating?
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Wed, 23 June 2004 16:31
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Did you bring your car to Kmart??
i'll never ever bring my car to kmart again, they suck!!
last week, my clutch ware off, and need to replace a new clutch. The cost in Kmart is ...... $8XX 
i just get shocked at that moment, then i had a discuss with my firend, and asked the cost of replacing a new startard clutch in another shop, which is $360........
i'm in melbourne
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Location:
Sydney
Registered:
October 2003
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Re: 4AC makes POP sound when not accelerating?
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Wed, 23 June 2004 17:35
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my ex flatmates car was suffering fromt he same problem. it was retarded timing.
fixing as per the workshop manuals specs it fixed the problem.
Dom.
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Club Member
Location:
sydney
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Wed, 23 June 2004 22:07
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| Quote: |
my 4ag crackles like a mofo on overrun
vrooommmmmmmm *bak* *bak* *bak* *bak* *bak*
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LOL mine sounds like Garths.... do it again Garth .. do it again!
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Location:
Wollongong, NSW
Registered:
October 2003
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Re: 4AC makes POP sound when not accelerating?
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Wed, 23 June 2004 22:58
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Do you have an aftermarket exhaust on your car?
All four cylinder cars I have driven do this. It normally happens when you go back a gear to slow down whilst descending a hill. An aftermarket exhaust will exacerbate the sound, but really it's nothing to worry about.
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Club Member
Location:
sydney
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Thu, 24 June 2004 03:28
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aftermarket exhaust... yes actually apart from the shell i dont think i have anything stock on my car LOL oh except the suspension.. at least till i get the coiliovers on 
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Location:
Canberra ACT
Registered:
November 2002
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Re: 4AC makes POP sound when not accelerating?
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Thu, 24 June 2004 04:03
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My 4AC AE82 has been popping pretty much all of it's life. Even when I replaced the engine the same popping was there.
Sounds great through the 2" sports system! More like a BOOM than a pop
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Location:
On your mum!
Registered:
May 2002
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Re: 4AC makes POP sound when not accelerating?
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Thu, 24 June 2004 08:04
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If you disconnect a a polution pump they will pop until you block the ports in the manifold with proper plugs.
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