5.0 Ticking Under Load when WARM, P0402 Code

[sulaco83]

Ever since I picked my 5.0 EB up over the summer, I've been struggling with the EGR system. I realized shortly after picking it up that someone had messed with the system since the green vacuum line coming from the EGR valve had been disconnected and plugged with a bolt. After reattaching, the truck promptly threw a P0401 code. I replaced the DPFE sensor which fixed that problem, but ever since I have been getting a ticking sound when under load and twice over the last 2 weeks I have gotten a P0402 code (EGR Excessive Flow).

Unlike most of the other posts I have seen, the truck does NOT tick when cold, but only begins to tick (at least as far as I can tell) when it has warmed up. This seems strange and sort of the opposite of the way exhaust leak noises are supposed to work. My local mechanic checked the truck out and couldn't find any sign of a leak. It runs absolutely fine but the noise and occasional CELs are starting to get on my nerves.

My guess is it has something to do with the EGR tube or maybe even the valve, but I was wondering based on the symptoms if someone could tell me which is the more likely problem? I would think if it was a cracked header it would be ticking worse when cold, not when warm.

 

[delexploder]

Get a mechanics stethoscope, you would be surprised how such a simple tool will allow you to pinpoint what's wrong,

 

[sulaco83]

Looks like it was my EGR valve itself. I took off the vacuum line to the valve and plugged it and no more noise or check engine light. I ordered a new one and I've added it to my list of things to do once it stops being so cold!

 

[sulaco83]

Nevermind

Just realized I never updated this thread. It wasn't the EGR valve after all. I replaced the valve, tube, dpfe sensor, and solenoid and am still getting the code. There is definitely a distinct ticking noise under load which I think is now louder than it was before, and it is still throwing a P0402 code. I can only imagine it must be a manifold leak but I took it to 2 seperate mechanics and neither could find anything wrong even after I took the heat shield off. What a headache!

 

[RomeovilleIL]

So when the EGR was disconnected and had the exhaust plugged, what issue was it giving you that prompted this process in the first place?

 

[sulaco83]

It threw a P0401 code