Good day to you all.

I am having a strange issue with my truck that is difficult to describe.

Info about the truck:
2000 XLT 5.3 144k miles.

Issue:
Under load when in the higher RPM range the truck makes, what I can only describe as, a puffing noise. A quick succession of puffs. I am not sure if it feels like its missing or backfiring.
It does not do it under light acceleration and oddly enough I only hear it for a second when WOT.
It does not happen when in park at any RPM.

My Thoughts:
Truck recently got a muffler chop aka straight pipe. Could that have something to do with it?
Spark plugs again? I know the previous own did them but I don't know when exactly.

Any ideas or suggestions would be awesome sauce.
Thanks.

 

Just sounds characteristic of a truck with no muffler... kind of like a gargle. Maybe video would help.

 

Doesnt really sounds like a gargle. More like puffling, clicking, backfiring in quick succession.

 

Run the OBD II codes and see if anything is setting in the PO30X range. This will tell you if your cylinder(s) are in a misfire condition or not. It could be a different set of codes, but for sure, this is what I'd do first thing.

No reason to try and guess.

 

You mean hook up a scan tool?

Correct me if I am wrong but if the CEL light is off then its not throwing any codes?
If its misfiring it should throw a code correct?

 

Only after it detects a TON of misfires. Engines misfire all the time. The misfire code only pops a light if the timer / counter is over limit.

Likewise, you could have several pending codes that haven't yet popped a CEL because they haven't been there long enough, but they will still show when you do a pull.

 

Check the PCV valve. An overly restrictive Fram or other PCV can do exactly as you describe. When conditions are right, it may even play a tune for yuh. These engines need wide valve margins to breath properly. Only a Motorcraft valve will suffice...so far anyway.

 

Interesting. I plan on doing an gotts mod this weekend. Might as well climb in there and check the valve.

Strangely enough the truck hasn't done it since but it has also not been as cold as it was that night either.

 

Just to be clear, I referring to noise you described only, in case you were unaware. So yea, if the noise is in that general area. When/if your running a restrictive like that, they can sound off at any time, out of the blue. The last one I heard doing mimicked a bad rod knock. Sounded just like it lol. It's the Fram valves usually...they can be cruel lol.

 

New to forum and don't know where to ask. Have 2000 f150 5.4 4wd. Runs great when sunny, but when rains completely dead, nothing. But when quits raining, jump and starts and no more problem till rains again. Once was driving and started raining, wipers would start and stop, power windows would start and stop. Noticed once that would do nothing that radio was on, and fan blower was on and no key was in ignition or switch was on. Help please, or do I need an exorcist.