[Misty]

Hi there i recently just replaced my cats due to the old ones going bad. i had them replaced but now when you start the car the catalytic converters are glowing red. Any ideas whats wrong? all spark plugs have been replaced

[Meeni]

You are running lean, either a vacuum leak post-O2/MAF on the intake, or a low pressure on the fuel rail. Should have shadow codes in the computer in both cases regarding incorrect mixture and timing corrections.

[robthewrench]

I second the lean or wrong fuel mix condition. You have un-burnt fuel making it's way into the exhaust and it is getting burned in the cats, creating heat and turning them red.

This is also possibly the reason the previous set of cats went bad. Get it checked out, or you'll quickly be in the market for a 3rd set of cats.

[mxchris727]

Originally Posted by robthewrench

I second the lean or wrong fuel mix condition. You have un-burnt fuel making it's way into the exhaust and it is getting burned in the cats, creating heat and turning them red.

This is also possibly the reason the previous set of cats went bad. Get it checked out, or you'll quickly be in the market for a 3rd set of cats.

That would be a rich condition.

[robthewrench]

Originally Posted by mxchris727

That would be a rich condition.

He didn't mention the idle being too high which is typically a symptom of an overly rich condition. It's hard to add extra fuel to the cylinder without increasing the RPMs.

However, this is still a possibility, so I think the best description is wrong mix.

In a really lean condition, the cylinder will not ignite at all, which is a mis-fire. All the fuel is then dumped into the exhaust.