Popping Sound from Exhaust while decelerating

sumeethaldankar · 2nd October 2008, 10:50

Hi,
My 800 with a carb engine experiences a popping sound from the exhaust
mostly while decelerating in 2 gear.Any ideas what could be the cause of
the same?
My cars equipped with a Automech exhaust,is this common for Free Flow
Exhaust?

ilangop · 2nd October 2008, 11:17

It should be due to some misfire while you suddenly decelerate. It is common in many Premeir 118 NEs too. You can get the timing and the carburettor air and idle screw settings checked. This also happens when the idle speed is too too low.

amitpunjani · 2nd October 2008, 11:19

hi buddy

Get the ignition timing checked.Noramally the backfiring occurs in case there faulty ignition timing

Amit

dustDevil · 2nd October 2008, 19:29

Same problem with my automech equipped Carb Zen.
The probem started after a regular service. The mechanic says a tune-up will get rid of it, but I'm still to find time. I'll update once its done.

sumeethaldankar · 2nd October 2008, 22:00

Quote:

Originally Posted by dustDevil

Same problem with my automech equipped Carb Zen.
The probem started after a regular service. The mechanic says a tune-up will get rid of it, but I'm still to find time. I'll update once its done.

Hey dustDevil do let me know the outcome of your car's tune up job.
thanks

Shan2nu · 3rd October 2008, 00:36

Popping sound in the exhaust while decelerating is called "afterfire", generally caused due to a rich mixture. Get the AFR tuned by your mech. This should solve the prob.

My VTEC has this as well (running rich due to faulty O2 sensor).

FE has gone down a bit but interestingly the performance of the car is excellent.

Checkout the afterfire on this beast (sounds like diwali fire crackers) -

YouTube - WRC VS. Focus

Shan2nu

Cyrus43 · 3rd October 2008, 00:51

It is caused by underfueling. When you suddenly leave the throttle at higher revs, the ECU stops feeding Petrol. Thus it is basically non fueled combustion. Also, It could be due to a leaking intake valve.

adi99 · 3rd October 2008, 01:34

Quote:

Originally Posted by ilangop

It should be due to some misfire while you suddenly decelerate. It is common in many Premeir 118 NEs too. You can get the timing and the carburettor air and idle screw settings checked. This also happens when the idle speed is too too low.

Exactly! This is how I used to get my problem rectified with my 99 Zen Carb. I have the muffler in my zen which make noise, so you can easily make out the misfire! Not a big issue my friend, few minutes and the problem is solved

shrivz · 3rd October 2008, 01:35

My baleno's been "afterfiring" after the 100,000km mark when the guys at MASS changed the timing belt. Now, I believe its a timing issue.. could anyone shed some more light on this, whether its due to too retarded igniting timing, or too advanced?

n_aditya · 6th October 2008, 13:11

Quote:

Originally Posted by Shan2nu

Popping sound in the exhaust while decelerating is called "afterfire", generally caused due to a rich mixture.

Checkout the afterfire on this beast (sounds like diwali fire crackers)

I remember seeing a Nissan sedan in Blore which had a similar afterfire and loved it. It was a series of purr purr sounds followed with some sparks from the tail pipe when downshifted.

Any ill effects of this state of tuning?

Samir Taheer · 21st October 2008, 21:07

I would get the Timing checked - If the mechnic says its spot on, ask him to retard it (i think) a bit. See if it makes a difference. The exhaust could have altered the amount of back pressure required and so you have the exhaust gas flowing out of the cylinder faster than is required - again i think.

I wouldnt have thought it has any adverse effects. A friends been running his gypsy king like that for years.

Never been to automech - but have they ever proved their exhausts?

Samir Taheer · 21st October 2008, 21:08

Cyrus - its a Carbed 800 - Wouldnt have thought theres an ECU.

pranavt · 22nd October 2008, 08:58

Love this sound, is this normal on all FFE cars or do you need to tune/change something to get it?

rdkarthik · 22nd October 2008, 10:19

Popping through the exhaust is usually a combination of lean (at times rich )mixture and retarded timing.. On some higher end cars features like launch control, anti-lag, etc can cause similar effects.

amit_mechengg · 9th November 2008, 00:57

seems as my alto is nearing 40k kms, so many problems are arising. since yesterday i am hearing strange "Sat" "Sat" bursting sound from beneath my car.
its like the same sound that occurs on bikes when the silencer is blocked with carbon. but i have never heard from anyone that this comes from car too.

what could be the reason? how serious is it?

2nd October 2008, 10:50	#1
sumeethaldankar Senior - BHPian Join Date: May 2007 Location: Mumbai Posts: 3,937 Thanked: 3,321 Times View My Garage	Popping Sound from Exhaust while decelerating Hi, My 800 with a carb engine experiences a popping sound from the exhaust mostly while decelerating in 2 gear.Any ideas what could be the cause of the same? My cars equipped with a Automech exhaust,is this common for Free Flow Exhaust?
	() Thanks

2nd October 2008, 11:17	#2
ilangop BHPian Join Date: Jul 2008 Location: Chennai Posts: 992 Thanked: 903 Times View My Garage	It should be due to some misfire while you suddenly decelerate. It is common in many Premeir 118 NEs too. You can get the timing and the carburettor air and idle screw settings checked. This also happens when the idle speed is too too low.
	() Thanks

2nd October 2008, 11:19	#3
amitpunjani BHPian Join Date: Jul 2007 Location: Delhi Posts: 451 Thanked: 109 Times	hi buddy Get the ignition timing checked.Noramally the backfiring occurs in case there faulty ignition timing Amit
	() Thanks

2nd October 2008, 19:29	#4
dustDevil BHPian Join Date: Jun 2006 Location: Surat Posts: 159 Thanked: 16 Times View My Garage	Same problem with my automech equipped Carb Zen. The probem started after a regular service. The mechanic says a tune-up will get rid of it, but I'm still to find time. I'll update once its done.
	() Thanks

3rd October 2008, 00:51	#7
Cyrus43 Join Date: Nov 2006 Location: London Posts: 5,019 Thanked: 221 Times View My Garage	It is caused by underfueling. When you suddenly leave the throttle at higher revs, the ECU stops feeding Petrol. Thus it is basically non fueled combustion. Also, It could be due to a leaking intake valve.
	() Thanks

3rd October 2008, 01:35	#9
shrivz BHPian Join Date: Jan 2006 Location: Pune, MH12 Posts: 604 Thanked: 96 Times View My Garage	My baleno's been "afterfiring" after the 100,000km mark when the guys at MASS changed the timing belt. Now, I believe its a timing issue.. could anyone shed some more light on this, whether its due to too retarded igniting timing, or too advanced?
	() Thanks

21st October 2008, 21:07	#11
Samir Taheer BHPian Join Date: Sep 2008 Location: London & Pune Posts: 459 Thanked: 278 Times	I would get the Timing checked - If the mechnic says its spot on, ask him to retard it (i think) a bit. See if it makes a difference. The exhaust could have altered the amount of back pressure required and so you have the exhaust gas flowing out of the cylinder faster than is required - again i think. I wouldnt have thought it has any adverse effects. A friends been running his gypsy king like that for years. Never been to automech - but have they ever proved their exhausts?
	() Thanks

21st October 2008, 21:08	#12
Samir Taheer BHPian Join Date: Sep 2008 Location: London & Pune Posts: 459 Thanked: 278 Times	Cyrus - its a Carbed 800 - Wouldnt have thought theres an ECU.
	() Thanks

22nd October 2008, 08:58	#13
pranavt Senior - BHPian Join Date: May 2008 Location: Mumbai Posts: 1,682 Thanked: 641 Times View My Garage	Love this sound, is this normal on all FFE cars or do you need to tune/change something to get it?
	() Thanks

22nd October 2008, 10:19	#14
rdkarthik BHPian Join Date: Sep 2005 Location: bangalore Posts: 206 Thanked: 13 Times	Popping through the exhaust is usually a combination of lean (at times rich )mixture and retarded timing.. On some higher end cars features like launch control, anti-lag, etc can cause similar effects.
	() Thanks

9th November 2008, 00:57	#15
amit_mechengg Senior - BHPian Join Date: Dec 2007 Location: Pune Posts: 2,488 Thanked: 2,252 Times View My Garage	Exhaust bursting sound from beneath the car-Help seems as my alto is nearing 40k kms, so many problems are arising. since yesterday i am hearing strange "Sat" "Sat" bursting sound from beneath my car. its like the same sound that occurs on bikes when the silencer is blocked with carbon. but i have never heard from anyone that this comes from car too. what could be the reason? how serious is it?
	() Thanks