Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 2nd October 2008, 10:50   #1
Senior - BHPian
 
sumeethaldankar's Avatar
 
Join Date: May 2007
Location: Mumbai
Posts: 2,668
Thanked: 1,018 Times
Default 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?
sumeethaldankar is online now   Reply With Quote
Old 2nd October 2008, 11:17   #2
BHPian
 
ilangop's Avatar
 
Join Date: Jul 2008
Location: Pune/Neyveli
Posts: 913
Thanked: 577 Times
Default

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.
ilangop is offline   Reply With Quote
Old 2nd October 2008, 11:19   #3
BHPian
 
amitpunjani's Avatar
 
Join Date: Jul 2007
Location: Delhi
Posts: 451
Thanked: 101 Times
Default

hi buddy

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

Amit
amitpunjani is offline   Reply With Quote
Old 2nd October 2008, 19:29   #4
BHPian
 
dustDevil's Avatar
 
Join Date: Jun 2006
Location: Surat/Pune
Posts: 155
Thanked: Once
Default

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.
dustDevil is offline   Reply With Quote
Old 2nd October 2008, 22:00   #5
Senior - BHPian
 
sumeethaldankar's Avatar
 
Join Date: May 2007
Location: Mumbai
Posts: 2,668
Thanked: 1,018 Times
Default

Quote:
Originally Posted by dustDevil View Post
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
sumeethaldankar is online now   Reply With Quote
Old 3rd October 2008, 00:36   #6
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

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) -

Shan2nu

Last edited by Shan2nu : 3rd October 2008 at 00:37.
Shan2nu is offline   Reply With Quote
Old 3rd October 2008, 00:51   #7
BANNED
 
Join Date: Nov 2006
Location: London
Posts: 5,012
Thanked: 147 Times
Default

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.
Cyrus43 is offline   Reply With Quote
Old 3rd October 2008, 01:34   #8
BHPian
 
adi99's Avatar
 
Join Date: May 2007
Location: Bangalore
Posts: 274
Thanked: 2 Times
Default

Quote:
Originally Posted by ilangop View Post
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
adi99 is offline   Reply With Quote
Old 3rd October 2008, 01:35   #9
BHPian
 
shrivz's Avatar
 
Join Date: Jan 2006
Location: Pune, MH12
Posts: 603
Thanked: 92 Times
Default

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?
shrivz is offline   Reply With Quote
Old 6th October 2008, 13:11   #10
Senior - BHPian
 
n_aditya's Avatar
 
Join Date: Oct 2005
Location: Namma Bengaluru
Posts: 5,206
Thanked: 2,742 Times
Default

Quote:
Originally Posted by Shan2nu View Post
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?
n_aditya is offline   Reply With Quote
Old 21st October 2008, 21:07   #11
BHPian
 
Samir Taheer's Avatar
 
Join Date: Sep 2008
Location: London & Pune
Posts: 392
Thanked: 60 Times
Default

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 is offline   Reply With Quote
Old 21st October 2008, 21:08   #12
BHPian
 
Samir Taheer's Avatar
 
Join Date: Sep 2008
Location: London & Pune
Posts: 392
Thanked: 60 Times
Default

Cyrus - its a Carbed 800 - Wouldnt have thought theres an ECU.
Samir Taheer is offline   Reply With Quote
Old 22nd October 2008, 08:58   #13
Senior - BHPian
 
pranavt's Avatar
 
Join Date: May 2008
Location: Mumbai
Posts: 1,628
Thanked: 272 Times
Default

Love this sound, is this normal on all FFE cars or do you need to tune/change something to get it?
pranavt is offline   Reply With Quote
Old 22nd October 2008, 10:19   #14
BHPian
 
rdkarthik's Avatar
 
Join Date: Sep 2005
Location: bangalore
Posts: 206
Thanked: 11 Times
Default

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.
rdkarthik is offline   Reply With Quote
Old 9th November 2008, 00:57   #15
Senior - BHPian
 
amit_mechengg's Avatar
 
Join Date: Dec 2007
Location: Pune
Posts: 2,406
Thanked: 1,538 Times
Default 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?
amit_mechengg is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Santro Engine Dies When Decelerating - NOT ALWAYS vigsom Technical Stuff 11 11th March 2015 15:04
Indigo DICOR 3rd and 5th gears popping into Neutral automatically. wanderernomad Technical Stuff 3 8th April 2011 22:27
Ultima GTR-640! Fastest accelerating and decelerating production car Gordon The International Automotive Scene 3 4th August 2005 19:02


All times are GMT +5.5. The time now is 08:09.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks