Today I revved the engine to show some coworkers the sound of my RAVIN muffler. It popped real loud like a backfire. It happened twice. What does this mean?

 

I assume you have an 04 or 05 F150.What size engine,how many miles on it,does it do it while you are driving,how long have you had the muffler on,did you use stock exhaust pipes,which style Ravin do you have,is it stainless,did you weld or clamp on and is truck still under warranty?I am not familiar with Raven,but the pressure sound (backfires) do not sound normal.It could be tune-up related.

 

my 2005 FX4 has a little backfire with a flowmaster 50 series. does it when the engine is not at operating temp and is revved just a little. it runs fine, so i'm not worried about it.

 

I don't know if the same rules apply but, on a fuel injected Harley you get a lot of popping when you change to a free flow exhaust. It's most noticable on deceleration. It's because the engines are set up to run very lean so they'll meet EPA spec. The free flow exhaust makes them even leaner. On bikes you can correct it by tweeking the computer mapping. Of course you'll need a Microtuner or something similar to do that.

 

One reason is vehicle speed, engine rpm and sensor input(O2 etc) are all inputted to the ECM. Depending on the temperature of the engine, the temp of the oxygen sensor air temp, the ECM really may have only relied on the fixed maping to some degree. If you have the 5.4 2004 or newer, the actual cam timing (since it has variable timing), along with the intake control valves ( not intake valve) could have not been in line with the rpm due to the same factors previously mentioned. Therefore, spark advance and fuel metering may not have been at ideal conditions. I wouldn't worry about. There is not much tuning you can do to these newer vehicles other than change the plugs. The spark and fuel are all metered by the ECM. The only reason you may be hearing more now is the baffling has been reduced, causing less suppression.

Exhaust wiull not make the engine run much leaner, the O2 sensors measure the exhaust gasses and informs the ECM to adjust the fuel air ratio to 14:1. Prior to O2 sensors I would agree!

 

all that was done, was a stock muffler replacement with a RAVIN. It does not happen when the engine is at operating temp from what I can tell. pipes into and out of the muffler are stock.