Just replaced my IAC, EGR, and PCV valves..

[OverlandExpy]

Aaaand still have the slightest of rough idles. No chain slap at startup, and I replace my oil with full synthetic 10w30 every 3000 miles or less. (I live in a pretty warm area, never gets below freezing so I don't use 5w30). No breather leaks as far as I can tell, I haven't smoke tested it yet but I don't hear any hissing or any other indication of a leak.

Also thoroughly cleaned out my throttle body and adapter.

I may just be an idiot, but how do I know if the vibrations I feel at idle are just normal for a v8, or if there is some timing issue? The rpms are nice and level at idle, and the engine runs as smooth as a baby's bottom when I'm in gear at a stand still or while driving. It's just the slightest rumble when I'm in neutral letting it idle.

Got about 155k miles on it.

Attached picture is of the old parts, none of them seemed outright broken, just really dirty.

 

[whtbronco]

I was gonna suggest a smoke test. You might also consider simply replacing some of the rubber vacuum hoses and connectors. They are getting old and hardening and possibly not sealing really well. They may even be beginning to disintegrate. For instance I had to replace the heater valve vacuum connector since it got loose. The small like 2" hose for the vacuum reservoir behind the battery had a super small split in it. Anyway, just a thought as age is terrible on rubber.

Thankfully these small pieces can be replaced as time permits and the cost is low. There's a plastic T connector that has a couple short sections of vacuum hose in a line that runs across the front of the intake manifold. I just used some 3/16" or maybe it's 1/4" fuel hose to replace the short rubber hose sections.

After my recent timing job my idle it back to just over 600rpm in gear, it had been around 550 and felt slightly rough there. I did swap a couple small sections of vacuum hose while I was putting it back together just because they didn't feel soft and pliable.

 

[OverlandExpy]

Yeah smoke test is really the only other thing I can do. It's been in my Amazon cart for a year or two now, just pulled the trigger on it and I'll test it next week. Was thinking the brake booster vacuum line would probably be the best place to do the smoke test. Any other spots I should put the smoke it or just there?

 

[whtbronco]

I just use whatever hose I can make fit the ports on my homemade smoke tester.

 

[OverlandExpy]

Did a smoke test, plugged the air box and ran the test. A bunch of smoke started pouring out of this hole in the egr. Is that supposed to happen? Coming out of the brand new one I just put in, the old one has the same hole.

@Hamfisted any idea if this is normal? I figure you know pretty much everything about these engines lol

 

[OverlandExpy]

No other leaks that I could find thankfully. Was thinking of plugging this hole then running it again just in case. Plugged the smoke machine into the brake booster line

 

[whtbronco]

I sure don't recall seeing any smoke from the EGR. There's a rubber diaphragm in the top there that should seal off the top half from the bottom half I believe. So I don't think smoke should be getting to that hole. Unless I'm wrong the vacuum line on top of the EGR will be able to suck outside through that small hole if the diaphragm isn't sealing.

I'm interested to see what Hamfisted has to say about it.

 

[Hamfisted]

Did a smoke test, plugged the air box and ran the test. A bunch of smoke started pouring out of this hole in the egr. Is that supposed to happen? Coming out of the brand new one I just put in, the old one has the same hole.

@Hamfisted any idea if this is normal? I figure you know pretty much everything about these engines lol

As strange as it seems, yes, it is normal for smoke to pass through that vent hole in the EGR valve. It confuses a lot of people. You'll also notice some escaping from the idle air control valve vent.

.

 

[whtbronco]

Hmm, yeah I expected and recall seeing some from the IAC. The EGR I don't and doesn't make sense to my feeble little mind. Time for more research.

 

[OverlandExpy]

Thanks ham, that makes sense! Should I just tape over the holes to smoke test it or is there a better place to insert the smoke machine?

 

[Hamfisted]

Thanks ham, that makes sense! Should I just tape over the holes to smoke test it or is there a better place to insert the smoke machine?

You don't need to tape over those two known spots. Just look for any other leaks, there shouldn't be smoke from anywhere else.




.

 

[OverlandExpy]

No other smoke that I could see but wasn't sure if it was all leaking out the egr and if I could find another leak if I plugged that one.