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Ivan, ASE Certified Master Technician
Category: Car
Satisfied Customers: 4871
Experience:  ASE Master Tech w/ 20+ years in the field. Self employed for 9 years. Member of AUTOLAB radio show.
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What causes red hot exhaust after running a few minutes

Customer Question

What causes red hot exhaust after running a few minutes
Submitted: 7 years ago.
Category: Car
Expert:  OnlineHelp replied 7 years ago.
Hello and thank you for choosing Just Answer.

Typically that indicates that it's stuffed somewhere. Usually it's the catalytic converter, which restricts the flow of the exhaust gases, which cause it to turn cherry red. You may want to take off the exhaust system and check the converters.
Customer: replied 7 years ago.
already replaced the catalytic converters and engine computer
Expert:  OnlineHelp replied 7 years ago.
You many need to take them off, take off the whole exhaust system and blow through with a shop compressor. It has to be a restriction in the pipes, either the converter, the resonator or the muffler.

Also which part of the ehxuast get red? Is it the manifold or the whole exhaust?
Customer: replied 7 years ago.
The exhaust manifolds The system was flow tested after I replaced the catyltic converter and resonator.
Expert:  OnlineHelp replied 7 years ago.
Okay if it's just the exhaust manifolds then it's probably running lean.
A lean mix ignites earlier, burns way hotter and is still hot leaving the
cylinder, and at the manifold you'll see temps as much as 300F hotter
than normal. This can turn the exhaust manifolds into cherries.
Customer: replied 7 years ago.
ok what causes it to happen I have changed the engine computer fuel pressure regulator
Expert:  OnlineHelp replied 7 years ago.
It's most likely your supercharger. A lean mixture means there is too much air coming in. You have a car with forced induction (supercharged). You may want a gauged hooked up to see how much the supercharger is putting out.
Customer: replied 7 years ago.
at 2200 rpm it has 2.4 pounds of boost
Expert:  OnlineHelp replied 7 years ago.
Did you have your fuel pressure tested?
Customer: replied 7 years ago.
Yes between 36 46 psi
Expert:  OnlineHelp replied 7 years ago.
Well, everything seems to check out fine. 2.4 pounds is nothing....your fuel pressure is fine and the exhaust system is good. I am lost here, I am going to opt out and open it back up to all experts. You will not be charged for my assistance.
Customer: replied 7 years ago.
thank you for your help
Customer: replied 7 years ago.
Thank You
Expert:  Ivan replied 7 years ago.

HelloCustomer I'm jumping in to help. Do have the ability to see data from the computer. We definately have either a very lean condition, or a very rich condiiton with fuel entering the exhaust. Does this thing start glowing at idle?


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