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[valliant72]

Hi, would anyone know what is causing popping in the exhaust when started from cold, the cambelt has been done at VX, rocker gaskets been done, breathers cleared, changed plugs, ht leads, air filter, fuel filter, cleaned throttle body and icv, replaced Crank sensor, thought that would of sorted the popping but hasnt. Only pops when cold then as it warms goes away. Any ideas  :-?

[bob.dent]

I had something like this a couple of years ago on my previous 2.5 V6 Omega. I had new mid section exhausts (not genuine VX) fitted and it turned out the exhaust had been badly manufactured and the baffles were breaked. Had it replaced under warranty but will stick with genuine VX in future.

[tmx]

Secondary Air Injection system is doing its job my v6 vectra done it and my mig does it but only when its been frosty over night

[Kevin Wood]

Does it have any leaks in the manifolds or exhausts? Could be air leaking in somewhere? Does the popping only happen when the secondary air injection is active?

Kevin

[tmx]

Kev myn does it when SAI is active is myn ok?

[valliant72]

The popping only happen when left over night then started from cold, but lasts only a minute as the engine starts to warm then goes away. When is the secondary air injection meant to come in?. There are no leaks from manifold from what i can tell. Once its past the popping it runs ok, if u trun off and start again then theres no popping.

[Kevin Wood]

Secondary air injection pumps extra air into the exhaust while a rich mixture is burning in the engine, so you have a mixture of air and fuel in the exhaust which can ignite and cause popping. I'd say it's probably nothing to worry about unless it continues after the SAI has stopped (a minute or two after startup)

Kevin

[valliant72]

Searching the internet on the problem, some ppl have had problems on american cars with the popping happening and as kevin wood said is to do with the secondary air injection, but they were saying the popping is caused by the SAI malfuntioning. Is there a way of testing it?

[tmx]

the ECU controls the SAI and if its playing silly beggars it flags it up as a DTC try the paperclip test

[valliant72]

yea i did the paper clip test, all i get is 135 which The boy said to ignore and the crank sensor which hasnt seemed to of cleared yet.

[albitz]

you could just disconnect it ,many people do.later cars didnt have it.

[valliant72]

Just an update, may of cured the popping, thought id check the tightness of the bolts to the plenum since VX changed the rocker gaskets. Found one bolt loose, so may of been letting air in, but since tightening to torque setting it hasnt popped. just gonna keep my fingers crossed now.