[BVAMotorsports]

I tried to use the search, but it is disabled, so please forgive if this has been beat to death.
I noticed that my car backfires a bit on deceleration, especially when it's cold. I wanted to see if this is normal. It's a 2.0L with a header, no cat, and TT 2.25 exhaust, stock chip, stock injection, Motronic. The exhaust sounds a bit rattly, from the header, but it almost sounds like I am getting a small flame out the exhaust when it backfires.
The car seems to run well (I haven't really had a chance to take it out for a good run yet), no smoke, idles smoothly.
Any clues, or is this just normal?

 

[AntoineJo]

Re: 16V Slight backfire on deceleration (beetlevdubn)

My 8v, in the exact same circumstances (cold, deceleration), can backfire very loudly on distances up to 40m or 50m.

cam, header, cat, 2.5in ex., perf. muffler...

 

[Elwood]

Re: 16V Slight backfire on deceleration (beetlevdubn)

Where do you have the ignition timing set? If its too far advanced, you'll get a backfire.

 

[GTibunny16v]

Re: 16V Slight backfire on deceleration (VWhombre)

My 8v and 16v both did it when i had a header on the 8v and TT race pipe on the 16v. No cat on either of them. On decel i would get a popping. Nothing to worry about, its just your motor trying to slow down the car. You'll get it on a car with very little backpressure. My 8v was at 12degrees BTDC and my 16v has stock timing.

 

[BVAMotorsports]

Re: 16V Slight backfire on deceleration (VWhombre)

Timing is set stock. Usually a retarded timing setting will give backfire out the exhaust, too far advanced will start to backfire through the intake.
thanks for the help guys.

 

[vwdohc993]

Re: 16V Slight backfire on deceleration (beetlevdubn)

i have a techtonics race header which has no flex pipe so I had to make my own it has a slight exhaust leak because it has to in order to work what i am getting at is i think it backfires because of the cold air and exhaust leak reacting to each other. My car backfire when it is cold out thats why I came to this conclusion good luck

 

[lotus7]

Re: 16V Slight backfire on deceleration (beetlevdubn)

It's the nature of the design of the exhaust . No one seems to know exactly why though.

 

[sloppychicken]

Re: 16V Slight backfire on deceleration (beetlevdubn)

backfire or popping on deceleration is the sign of an intake leak

 

[BVAMotorsports]

Re: 16V Slight backfire on deceleration (sloppychicken)

Hmmm, strange....if that were the case, I think that I would have idle issues, and I don't.

 

[AntoineJo]

Re: 16V Slight backfire on deceleration (beetlevdubn)

Interesting, because my 8V idles around 1000RPM frequently, hot OR cold. I never firgured it out before tucking it in for the winter. (not an ISV problem).

 

[metrowdub]

Re: 16V Slight backfire on deceleration (beetlevdubn)

You know dean i think you should just give me your rabbit.......rabbit's suck anyway!!!!!
Just kiding ..RABBIT'S RULE!!!!!
but i'll still take your bunny if you dont want it anymore!!!!!!
Anyhow ive got your e-brake cover waiting for ya!!!!
METRODUB<
http://****************.com/smile/emthup.gif

http://****************.com/smile/emthup.gif

 

[BVAMotorsports]

Re: 16V Slight backfire on deceleration (metrowdub)

Lets hook up this weekend, the windshield should get installed, so I can actually drive it faster than 30 mph.

 

[KV]

Re: 16V Slight backfire on deceleration (beetlevdubn)

Try checking your coolant temp sensor. it is possible that it is reading irregular voltage, maybe more so when cold vs. full temp? this can cause for a little too much fuel to sneak pass on decel'. what you're probably hearing is the "popping" sound from unburnt fuel traveling through the exhaust and igniting off a hot part of the exhaust tubing.
check your lamda values and the DFPR settings, they read hand-in-hand for CIS Motronic.
BTW - a little flame spitting is cool once in a while.
mt car w/ the Badger ITB's and TEC2 does it frequently

Kris Valdez

 

[16veebunny]

Re: 16V Slight backfire on deceleration (KV)

Dean - My car (2.0l 16v bunny with TTheader & 2.25"exh) did that too.
Idled great, ran perfect, but every now and then it would backfire a bit.
I was running a tad rich, though.
What chip are you running?

 

[BVAMotorsports]

Re: 16V Slight backfire on deceleration (16veebunny)

I actually have an Autotech, but haven't installed it yet. I want to see how this thing feels for a week or two, then put the chip in to see if/what kind of difference it makes.
What chip did you have in yours?

 

[Turbodub17]

Re: 16V Slight backfire on deceleration (beetlevdubn)

my nickname is "flame shooter". They ask how it shoots flames, I tell them... I don't know. I have a stock 2.0 16v with CIS-E and a cat back tt. That's it. I do have idle issues though. hmmm

 

[BVAMotorsports]

Re: 16V Slight backfire on deceleration (Turbodub17)

Sounds like you may have a bit of a rich condition, which may also be the reason for your idle issue. I don't think that mine has ever shot flames out the tailpipe, but then again, I haven't stood behind it when I decelerate.

 

[JdubsVW]

Re: 16V Slight backfire on deceleration (Turbodub17)

mine did that when i first got it and then about a few weeks later my coil went out like everyone else it probably is something to do with your spark start there and see what happens hope this helps some