Red hot cat normal?

[humpy999]

I've got a '16 F30 330e with 65k on the clock. I got a low washer warning on the drive home and as soon as I turned off I popped the bonnet to top up the tank and noticed that the cat was glowing red hot! I wasn't caning it back either; I live at the top of a steep hill but I wasn't nailing it by any means. Is this normal or should I be taking it in for BMW to look at?

[bmwmike]

Glowing red? Doesn't sound right at all!

[andym1603]

Has the performance dropped any? Seen this before where the core of the cat had collapsed basically plugging the exhaust causing the cat to glow red.

[humpy999]

No, no change in performance as far as I can tell, no warning lights. Unless I had opened the bonnet to replenish the washer fluid immediately following switch off I wouldn't have known. Wife had complained that as couple of times she had noticed a burning plastic smell after driving it...

[humpy999]

Crap photos but it was pitch black, but you get the idea.. same position looking at the exhaust manifold, different exposures

[anonymous-user]

Could be blocked or getting fuel burning in it.

Either way shouldn’t be like that.

[RUSSELLM]

If you give it some revs whilst stationary , is there any sounds of air induction leaks ?

[feef]

I've had a red-hot cat when a coil has failed or is starting to fail and the piston ends up pumping fuel into the exhaust system.

If it HAS got red hot tho, there's a good chance the core has now melted and won't be helping things.

My solution was to take the cat off and knock the remains of the core out with a steel rod (but this was on a supercharged MX5 with a standalone ECU so I could fettle the ignition map to ensure it still passed the MOT)

[Krikkit]

feef said:

I've had a red-hot cat when a coil has failed or is starting to fail and the piston ends up pumping fuel into the exhaust system.

If it HAS got red hot tho, there's a good chance the core has now melted and won't be helping things.

My solution was to take the cat off and knock the remains of the core out with a steel rod (but this was on a supercharged MX5 with a standalone ECU so I could fettle the ignition map to ensure it still passed the MOT)

You'd feel the misfire on a 4-cylinder engine though, and the engine management would be going crazy.

It'll also go batst crazy when you knock the cat out, being EU5.

[humpy999]

Thanks guys, booked in for BMW to look at... I'm worried that the turbo is right next door and parking it up for the night with a red hot outlet can't be good for cooking the oil there either?

[humpy999]

RUSSELLM said:

If you give it some revs whilst stationary , is there any sounds of air induction leaks ?

Nope, it's all normal, had a burning smell recently though...

[humpy999]

feef said:

I've had a red-hot cat when a coil has failed or is starting to fail and the piston ends up pumping fuel into the exhaust system.

If it HAS got red hot tho, there's a good chance the core has now melted and won't be helping things.

My solution was to take the cat off and knock the remains of the core out with a steel rod (but this was on a supercharged MX5 with a standalone ECU so I could fettle the ignition map to ensure it still passed the MOT)

It's a company car so whilst I might do that on my own car, I can't be bothered on this one. I was however thinking of buying it...

Edited by humpy999 on Friday 31st January 10:11

[humpy999]

Krikkit said:

You'd feel the misfire on a 4-cylinder engine though, and the engine management would be going crazy.

It'll also go batst crazy when you knock the cat out, being EU5.

[pedant mode on] EU6 [pedant mode off]

But I'm guessing either way it would spot the difference!

Edited by humpy999 on Friday 31st January 09:59

[humpy999]

Just to tie this off, BMW are fitting a new cat tomorrow... no codes so they assume an internal blockage.