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Popping in exhaust at tickover
whitestu - 25/3/09 at 09:44 PM

At tickover when warm I get an occasional pop in the exhaust.

I've balanced the carbs and got the AFR to a sensible level so I'm coming to the conclusion that this is being caused by a small airleak somewhere in the exhaust manifold.

Could this be the cause?


Stu

omega0684 - 25/3/09 at 09:46 PM

what AFR you running at idle?

possible dodgey injector or spark plug?

[Edited on 25/3/09 by omega0684]

Hellfire - 25/3/09 at 09:49 PM

Could be a small leak - if it's not too bad I wouldn't bother with it....

Steve

whitestu - 25/3/09 at 09:55 PM

The AFR is about 15 [ZX6R carbs]. I've played about with the idle mixture and it doesn't change the popping.

I've tried changing plugs and leads and it didn't make any difference.

As long as it doesn't muck up the emmissions at MOT I'll probably live with it.

Stu

jacko - 25/3/09 at 10:06 PM

Yes air leak in the exhaust

madteg - 25/3/09 at 10:08 PM

Is the engine missing at all on tickover.

coozer - 25/3/09 at 10:17 PM

quote:
Originally posted by madteg
Is the engine missing at all on tickover.


Mine does a little, what does that mean??

Steve

omega0684 - 25/3/09 at 10:26 PM

quote:
Originally posted by whitestu
The AFR is about 15 [ZX6R carbs]


really you run it lean, i thought it was best to run the car slightly rich at idle? or am i wrong?

Paul TigerB6 - 25/3/09 at 10:27 PM

Just a thought - if you have an air leak and you are taking the AFR reading after the point thats leaking, is it not possible that the reading is wrong and that the engine is actually running richer than you think??

Maybe totally wrong but i'm still learning.

paulf - 25/3/09 at 10:48 PM

Sometimes a bit of extra advance on the idle part of the map stops it , my zetec also occasionally does it but some extra advance just at idle revs helps.
Its also worth checking the plug leads as these sometimes break down .
Paul

whitestu - 26/3/09 at 08:53 AM

quote:

really you run it lean


I think the AFR needs to be about 14.7 to pass MOT CO emmisisons test.


quote:

Just a thought - if you have an air leak and you are taking the AFR reading after the point thats leaking, is it not possible that the reading is wrong and that the engine is actually running richer than you think??


Could be. Not sure how much it is affecting things.


quote:

Sometimes a bit of extra advance on the idle part of the map stops it , my zetec also occasionally does it but some extra advance just at idle revs helps.


I've tried fiddling about with advance, and it actually seems to like less advance at tickover. Its on 2 degrees at the mo, which is a lot less than it ought to be. What are you running?

Thanks
Stu

BenB - 26/3/09 at 09:32 AM

As said, if you've got an air leak upstream of the lambda sensor you can't trust your AFR.... As a temporary bodge try smearing grease over any joints to see if you can get it to stop. At least that should pinpoint the leak. I had terrible popping from the nearside can until I got out the firegoo....

DarrenW - 26/3/09 at 09:39 AM

Are you after more pops or less?

whitestu - 26/3/09 at 01:01 PM

Definately less!