Flames coming out the tail pipe

[Al Gray]

My son, Sean, is now driving the 1992 BMW 525i. He has replaced all the door panels that were delaminating, had the headliner re-upolstered, and put custom led taillights in the car. It is finally inspected and on the road. Today, he pulled out of our development and headed towards a major highway. He noticed a middle age guy behind him who was tailing him and gesturing to pull over. The guy pulled up to him and said that he saw "flames" coming out of the tail pipe!

Now, I have seen flames coming out of exhaust headers of race cars but from the exhaust manifold to the tail pipe is probably a good ten feet. The only thing my son has done recently is to run premium gas instead of regular in the car. The exhaust system is new from the catalytic converter back to the tail pipe.

My son said the guy was serious. Was the middle age guy smoking something, seeing things, or is it really possible that something like this could happen. If so, what are the causes and how do you go about correcting the problem. Help, Winfred!

[uscharalph]

I'd verify the flames 1st.

[repenttokyo]

could be the cat, but that's unlikely.

[winfred]

if the exhaust was on it's first trip down the road maaaaaaybe as the solvents in the paint burned off, but generally it just stinks a few minutes, if it was hot enough to sport flames from the tips it would of turned any paint on the pipes/muffler white and flaky all of the way to the tips, maybe even turning part of the pipes blue

pretty much i cry ******** unless theres evidence to support

[Al Gray]

[QUOTE=winfred]if the exhaust was on it's first trip down the road maaaaaaybe as the solvents in the paint burned off, but generally it just stinks a few minutes, if it was hot enough to sport flames from the tips it would of turned any paint on the pipes/muffler white and flaky all of the way to the tips, maybe even turning part of the pipes blue

pretty much i cry ******** unless theres evidence to support[/QU

I followed my son this evening and I saw NO evidence of flames out the tail pipe. The car appears to be running fine. I will keep an eye on it just in case.

[Bin_jammin]

Flames out the tailpipe is totally possible. It's usually caused by WAAAAAAAY too much fuel in the exhaust. I'd start looking for leaking injectors, that's usually the only way to get the ECU to dump that much fuel, a bad o2 sensor is pretty unlikely.

A cat melting down wouldn't be the cause of something like that, but a symptom. The materials in the cat aren't flamable, but if you've got too much fuel in the exhaust stream it can make a cat melt down. Basically I'd confirm the flames, but be careful as this can cause some decent damage to the car, you can burn exhaust valves and melt cats and o2 sensors, the rear fascia, and worst case scenario burn down your car. Also, if an injector is leaking raw fuel, check your oil level and smell the oil. You can have so much fuel that it washes down the cylinder walls, removing the oil on them that protects from scoring. This can lead to bad cylinders, but also to thinned out oil.

I'd get it to a shop ASAP, or if you know what you're doing, get diagnosing.

[Torque]

Seems fine to me.

If my car started shooting flames, I'd sure as hell leave it.

[Ross]

No way.

[Paul in NZ]

the only way that would happen in "normal use is on overrun from high revs when the car is at really good operating temp.But as the injectors shut down at anything over about 2500 rpm on overrun i dont see how it would dump gas into a very hot exhaust

[[1990]525]

It's probably those LED tails.