Ticking under load after 5.0 DPFE replacement

[sulaco83]

I replaced my DPFE sensor last weekend and everything seemed to go as planned. CEL shut off and she's running smoothly.

Problem is the third time I fired her up I am hearing a ticking noise under load like a slight exhaust leak right behind the dash. It's not making the sound when revved up in park so it's not easy to locate.

I re-used the vacuum lines for the sensor and I was wondering if I somehow punctured one while doing the job if that would result in such a noise? I'm wishing now I had just replaced the lines while it was already taken apart.

 

[AP9]

You likely have a leak in one of the lines. About a month ago I had to replace mine as it had melted. The lines were both very brittle from age and what not, on top of having part of the melted DPFE sensor on them.

 

[Turdle]

The early 98 headers also like to crack. You have to remove the heat shields to see it.

 

[sulaco83]

I think I figured out what is making the noise. Actually, it threw another P0401 code yesterday. Feeling around the DPFE I noticed a yellow vacuum line that is cracked wide open. I can't seem to find anywhere what exactly this does or if it would be responsible for throwing the code. Anyone know anything about this vacuum line?

 

[sulaco83]

Never mind. Fixed the cracked vacuum line which killed the CEL but the ticking continues. Brought to a mechanic who tells me yes it sounds like a leak but it's not bad enough to tell where it's coming from. Big help that was!