2.5 litre Omega- Secondary Air Injection

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Tue 29 Aug 2006 16:25
2.5 litre Omega- Secondary Air Injection - DavidA
I have a 1995 V6 2.5 Omega.

There is a rubber hose at each end of the valves which connects to the manifold pipes, and on one side I am getting it melting and blowing out in about 20 minutes of engine running.

Vauxhall suggested that I replace the valve unit at a cost of £132, however I would like to know if anyone has had this problem before to see if that is the probable cause of the problem.

Please Please help......
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Tue 29 Aug 2006 16:36
Secondary Air Injection - Number_Cruncher
What should happen, for a short period after starting is that the secondary air injection pump should run, the secondary air valve should open, and the engine tickoverspeed should be raised. This is to blow air into the exhaust, to enable the completion of the combustion reaction of the rich cold start mixture in the exhaust front-pipe, in order to get the lambda sensor and cat up to temperature quicker, to reduce overall emissions. After a brief period, typically a few minutes, this system should shut off completely.

In your case, it sounds like the valve has failed in the open position and/or the pump has failed. If the valve is stuck open, the pump won't last long, because it will be having exhaust gas blown over it backwards, where it was designed to blow clean (there's a seperate, tiny, air filter on the pump which people never bother changing) air forewards.

If this car were mine, and if I didn't use it for short journeys only, I would consider blocking off the secondary air valve. The cost will be that the engine will run in open loop for a little longer each time you start from cold, but once you are up to temperature, you will notice no difference.

If you do use the car for shorter journeys, bite the bullet, and repair the system -try Autovaux for cheaper parts.

Number_Cruncher
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Wed 30 Aug 2006 20:45
2.5 litre Omega- Secondary Air Injection - robert
I've seen this problem before.

Just replace the hose - its melting on the bend isn't it! As an experiment - just tape it up with black plastic insulating tape to see if it cures the problem - which I suspect it will.

Its caused by gradual degredation of the rubber - thats all.

HTH
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