It's not the EVAP canister.. it is exhaust.. Took wife for a ride.. (i'm partial tone deaf) and a sound i barely heard when under load.. SHE says IS REAL AUDIBLE.. sort of like pinging.. but the wrong tone, and not as "fast"... forwards, reverse.. no difference. Does not do it when simply revved.. has to be under a load..
Idles great.. runs smooth.. just this goofy sound & smell in the cab . Did rag in tailpipe test at idle.. no change.. she could not hear it do it.

91 F150, 5.0.. AOD... any ideas what could make such a noise, and leak an exhaust smell, but not be heard when not under load, or with a rag in the pipe?

I WAS able to get it to do it a little at a standstill.. by "brake torquing" it lightly..

Anyone? Where do I look??

 

Exhaust - Manifold leak. Can sound something like knocking or pinging.

 

ok, if i have a leak at the exhaust manifold...can this cause the o2 sensor to read wrong, and it run rich?? My MPG has dropped, and the exhaust does smell too rich now.

 

Found it... it's where the EGR line goes into the lower intake manifold... used a shop vac to pressurize the exhaust system... and that's where it's hissing out of...

same question.. can a leak here, cause it to run richer than normal??

 

Yes, it definitely will.

 

Great! Thanks, that's what I needed to know. part 's been ordered.. funny how fast you can remove the Upper plenum the SECOND TIME...after having done it a day before .. LOL!!! thank's again

 

Yes sir, experience is everything and so are freshly excercised fasteners. I could pull the upper intake on my old '92 F250 w/5.8L engine in 15 minutes after the initial R&R.

 

Lol around the 3rd time i did it i felt like a badass mechanic. Now i know everyone can do it so my manliness went down the drain haha