EGR System Driving me Nuts!

[sulaco83]

I've been having EGR issues since I picked up my 98 Ex 5.0 last summer. I keep thinking I have the problem figured out but it keeps coming back!

When I bought the truck, I noticed when I got home that the green vacuum hose going to the top of the EGR valve was plugged with an 8mm bolt. When I unplugged it and reconnected it, the OBD threw a P0401 Code.

I replaced the DPFE sensor and then it threw a P0402 code. After much consideration I decided it must be an issue with the valve and/or EGR tube. I replaced both yesterday and after a few minutes the CEL came back on.

There is a slight ticking noise under load from behind the dash that seems to go along with this issue. It sounds like a slight exhaust leak. I am guessing that whatever is leaking is also causing the CEL to light up.

I'm not really well versed on how the EGR system works, but I do know that if I plug the green vacuum line back up, the ticking noise stops. I think this probably rules out the leak being from the header itself?

Anyway I am just hoping for some insight because at this point I really don't know what I should try. Replacing the EGR valve and tube was a massive pain in my ass and I'm pissed it didn't work.

Thanks for any help you might be able to provide.

 

[vroomzoomboom]

look and see if there is any cracked vacuum lines.

 

[boominXplorer]

Or internally clogged rubber lines coming from EGR tube, they tend to corrode and clog going into the DPFE. I bet the ticking is the EGR tube is rusted and leaking at the flex bend.

 

[sulaco83]

Or internally clogged rubber lines coming from EGR tube, they tend to corrode and clog going into the DPFE. I bet the ticking is the EGR tube is rusted and leaking at the flex bend.

I actually replaced both the EGR Tube and Valve yesterday. Still having the problem.

 

[boominXplorer]

I actually replaced both the EGR Tube and Valve yesterday. Still having the problem.

What about the 2 rubber lines that come off the EGR tube?

 

[sulaco83]

What about the 2 rubber lines that come off the EGR tube?

I just pulled them off to make sure they looked okay. I ran a cleaning rod through them to make sure they were clear. I don't see any cracks or holes in them anywhere, and they have plenty of flexibility. I don't see anything wrong with the small hard plastic hoses either.

 

[sulaco83]

In the off chance it helps, I just uploaded a video to YouTube where you can hear the ticking noise. It's much more noticeable than it seems to be in the video but you can still hear it, especially after I stop and accelerate the second time.

https://www.youtube.com/watch?v=L_wryQGonYU&feature=youtu.be

 

[boominXplorer]

If you have replaced your EGR tube then its going to be manifolds or manifold gaskets. You can try to retighten the manifold bolts, they tend to back off over time.

Also with the engine running at idle, does that vacuum line have any vacuum that goes to the egr valve? It should not.

 

[Turdle]

Your exhaust manifold on the passenger side is cracked. You can cut the small zip tie sized straps to remove the heat shields and verify, but I am sure of it. The leak will cause inconsistent egr flow causing codes.

 

[sulaco83]

Also with the engine running at idle, does that vacuum line have any vacuum that goes to the egr valve? It should not.

If I pop off the green vacuum line coming from the solenoid to the EGR valve and put my finger over it at idle, there is suction. It is not supposed to do that? What does that indicate?

 

[sulaco83]

Your exhaust manifold on the passenger side is cracked. You can cut the small zip tie sized straps to remove the heat shields and verify, but I am sure of it. The leak will cause inconsistent egr flow causing codes.

That's pretty much what it sounds like. The thing that confuses me is why the noise would stop if the vacuum line from the solenoid to the EGR valve is plugged up. Wouldn't a cracked header make noise either way?

 

[boominXplorer]

If I pop off the green vacuum line coming from the solenoid to the EGR valve and put my finger over it at idle, there is suction. It is not supposed to do that? What does that indicate?

The solonoid for the vacuum line should be closed at idle. If the you follow that vacuum line it should go to a little black valve with 2 wires coming out of it, that's the solonoid. EGR flow is regulated through the RPMs and there should be none at idle or it will run rough. That solonoid could be stuck open causing one of your issues, not sure about the ticking though.

 

[sulaco83]

I guess the other thing that I don't understand is that the ticking noise under load is ONLY after the Ex has warmed up. I thought manifold leaks were supposed to be loudest when cold but when I first start up I can't hear anything.

I think my next step is going to be to replace the EGR Solenoid.... I sort of have it in my head it could be the source of the problem since the noise goes away when I disconnect it from the EGR valve.

 

[rb142]

I'm with Turdle. Check your exhaust manifold.

 

[sulaco83]

It's gotta be the manifold. The solenoid didn't do it and the ticking continues even with the vacuum plugged now. I must have made it worse when I was wrenching off the EGR tube.

So what can I do? I guess I am screwed into getting new headers?

 

[biff9703]

You can get replacement manifolds at a salvage yard. Save yourself some time and go to car-part.com, put your info in, and it will show you who has the parts and are close to you. Put distance and your zip code in where you have that option, and you will have an answer in seconds. That's how I got mine.

 

[rb142]

If you are going to get one from a salvage yard you need to be really careful that you aren't buying another cracked one -- there are a lot of broken ones out there.

First make sure the manifold is actually cracked, and that it isn't just a leak at the head or the down-pipe. You can probably see carbon tracking from a crack.

 

[jremington59]

If you have vacuum at idle going to your egr then you have a problem with your sensor that was stated earlier. Have you checked to make sure your spark plug and manifold bolts are tight?

 

[sulaco83]

I tried tightening up the manifold bolts. They weren't going anywhere. None of them appeared to have backed out.

I replaced the solenoid and there was still a slight vacuum at idle. The DPFE sensor was recently replaced as well, but maybe it's defective?

I am going to cut off the heat shielding on the manifold once I get some time to make sure there is a crack before I do anything rash.

I saw some posts regarding some stuff called Thermosteel which apparently some people have used to patch cracked manifolds. Could be worth a shot for $8.

 

[sulaco83]

Okay so I cut the heat shields off of the passenger side manifold. Surprisingly I didn't see a crack anywhere. What I did notice is white corrosive build-up around the 3rd (from the front) spark plug. I can't help but wonder if the ticking I am hearing is some sort of electric arcing caused by a bad wire? What do you guys think?