4age backfires now that i got exhaust fixed

[KLR16V]

I got a ke70 bigport 4age, running microtech d5.
The car was running fine, just a bit rich, before I got any work done to it.


Today I got a new dump pipe put on because the old one was shit.
Also a new piece of stainless pipe was put on after the resonator because the old piece was hitting against the rear axle.

Since the work has been done the car backfires when getting off the gas...really loud bangs sometimes.

And it also has like a rattling knocking sound coming from where the extractors meet the exhaust when the car revs and accelerates.

Does this mean that there is a leak in someplace where it hasn’t been welded correctly?

[EldarO]

timing!

rattling/knocking sound is probably somehting physical, whether its a loose joint on the exhaust/extractors, or a weld wasnt done properly, or its hitting the chassis etc. etc.

hell, could be an engine/gearbox mount, pretty vauge.

Eldar.O.

[KLR16V]

I don’t think that it’s the timing causing that knocking sound, the timing hasn’t been touched. The rattle sound is coming from the exhaust somewhere near the headers.

The car was running pretty much fine before I entered the exhaust shop, but when I drove out it was very different...

I don’t think that the exhaust could be hitting anywhere on the chassis.
I just got all that fixed so it doesn’t hit anywhere. Now the exhaust has a few more support brackets installed and the exhaust sits much further away from the chassis.

[EldarO]

timing could never cause that knocking sound.

im talking about the backfiring, just reset it.

pop the bonnet, and play with the throttle cable, rev the engine up, and see if you cna get it to knock, if it knocks, have a look and see what it is, if you still cant see it, get a mate to do that while you have a look under the car (a fair distance away obviously...)

Eldar.O.

[BigWorm]

In a situation like this you take it straight back to the exhaust shop, tell them the same thing you told us, then tell them to fix it!

A leak could cause the back firing, & a loost flange could cause a leak & a knocking rattle. But it shouldn't be up to you to fix it.

[oldcorollas]

yup, timing FTL... nothing to do with it.

the partially rich mixture, combined with sucking in of air during decel could cause backfiring within the exhaust.

totally agre with Bigworm... take it back and (ask first ... say please ) demand they fix it.. and explain what was wrong...

but first, have a wuick look when it's cold and see if you can feel anythign wrong (ie movement etc) with the flange... they may have just forgotten to do it up right....

[timgte]

one of the nuts for the extractors is under the distributer. sometimes if it gets stuck you have to take out the dizzy to get to it properly. if that was taken out then the timing may be out....just a thought.

[wiso]

even a pin hole in the exhaust can cause a backfire, my old 4age aw11 did this, i had a very small hole int he pipe before the muffler, and every time i let off the throttle, big bang

[KLR16V]

i got it fixed ppl.

turns out that there was a small pin hole where the bloke didnt weld up the pipe properly.

got him to fix it, now its running sweet as!!!!

all ther noises and backfiring has stopped, and the car goes harder too!!!

it suprises me that such a tiny hole can make such a difference

[EldarO]

i got it fixed ppl.

turns out that there was a small pin hole where the bloke didnt weld up the pipe properly.

got him to fix it, now its running sweet as!!!!

all ther noises and backfiring has stopped, and the car goes harder too!!!

it suprises me that such a tiny hole can make such a difference

now factor in my old exhaust having gaping holes in it

i always wondered why my idle was so erratic, why the boost remained same, yet performance varied widely.

exhaust = very important.

Eldar.O.

[old_mr2]

wiso wins!