Idle problem - PCV?
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5th Wheeling
Joined: Jul 2012
Posts: 31
Likes: 1
From: Virginia
Timing is not spot on, but it's close. I'll check it again tomorrow.
The weird thing is that, when this all started, I was backing down the driveway, not accerating, just moving under idle power. The idle just went to hell in an instant. Then, after replacing the TPS, it idles at 3000+ rpms.
I'll recheck timing and look at the throttle stop screw. I did find a vacuum line off rear of the passenger side valve cover. Couldn't find where it was supposed to be plugged in. I've got the vacuum manual, which I'll check tomorrow.
The weird thing is that, when this all started, I was backing down the driveway, not accerating, just moving under idle power. The idle just went to hell in an instant. Then, after replacing the TPS, it idles at 3000+ rpms.
I'll recheck timing and look at the throttle stop screw. I did find a vacuum line off rear of the passenger side valve cover. Couldn't find where it was supposed to be plugged in. I've got the vacuum manual, which I'll check tomorrow.
Lead Driver
Joined: Jan 2019
Posts: 5,083
Likes: 868
From: N.W. Alabama
That is where your PCV valve should be coming out from, and 3/8 hose going to the vacuum tree on upper intake, I forget what year they changed from it being on a barb fitting coming off upper intake at #8 port at back of intake, when they (5.0-5.8) got long in the tooth, the oil was sucked up through the fitting and went right into the top of the piston on port #8, and sometime cause hydralock, then a TSB came out when ord moved the hose to the center of the upper intake, Sorry for so wordy post
Thread Starter
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5th Wheeling
Joined: Jul 2012
Posts: 31
Likes: 1
From: Virginia
So, I finally got back to this today. A couple days ago, I found that the throttle cable was off. I must've knocked it off when swapping the TPS. So, With that reconnected, idle is around 1200. Not right, but, for now, I'll take it.
Still running like crap. So, I cleared the codes, then started it, then rechecked codes. Got a 63. Which is another TPS code. "63 - Throttle position circuit below minimum voltage"
So, it looks like I've got to chase an electrical problem (?)
I'll take any thoughts or ideas on this.
Still running like crap. So, I cleared the codes, then started it, then rechecked codes. Got a 63. Which is another TPS code. "63 - Throttle position circuit below minimum voltage"
So, it looks like I've got to chase an electrical problem (?)
I'll take any thoughts or ideas on this.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,199
From: Mojave, Ca
Vacuum leaks usually case the engine to run like crap when idling, but clear up at higher rpm. The sudden onset of this problems leads me to believe it was a instantaneous failure, like a vacuum line blowing off or splitting. Large vacuum lines the the pcv or brake booster hose, may cause this. Or your vacuum canister suddenly developing a massive leak.
Thread Starter
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5th Wheeling
Joined: Jul 2012
Posts: 31
Likes: 1
From: Virginia
Yeah, I agree that's what it seems like. But, what could be up with the strong (really strong) gasoline smell and heavy smoking form under the hood and the tailpipe? The smoke looks like oil smoke, bluish, but smells like gasoline.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
I haven't gone back to look, but A) Is your fuel pressure regulator working, or is the diaphragm blown, and overfuelling at idle, or B) It's *extremely* remote a possibility, but is there any chance that you're sucking fuel up through the Evaporative Emissions lines from the tanks? Like I say, it's *extremely super duper not likely, like 1:1,000,000* that it's doing that, but I *have* seen it happen, once. And I don't remember what caused it, but I think something was hooked up wrong. (Wasn't my truck, and it was *years* ago.)
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Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,199
From: Mojave, Ca
Thread Starter
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5th Wheeling
Joined: Jul 2012
Posts: 31
Likes: 1
From: Virginia
Fuel pressure regulator sounds like it could be a real possibility. It happened instantly, like someone threw a switch (or a diaphragm got ruptured).
I'll look into it tomorrow.
Thanks!
I'll look into it tomorrow.
Thanks!
Thread Starter
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5th Wheeling
Joined: Jul 2012
Posts: 31
Likes: 1
From: Virginia
OK. I replaced the FPR. Same idle problems. However, the yellow TAD vacuum line is disconnected, just hanging there. I know the TAD valve is back there (or should be), but I couldn't find it yesterday. Also found that the TAB valve has no vac line connected to it. Back when I got the Jasper engine, the mechanic said he didn't fool with any of the vacuum stuff, so I don't know if it was bad then. I suspect at least some of it was. The red line going to the canister is broken off midstream.
Found a good writeup of replacing vac lines, so that will be the next thing. Just going to replace all vacuum lines.
Found a good writeup of replacing vac lines, so that will be the next thing. Just going to replace all vacuum lines.
Lead Driver
Joined: May 2011
Posts: 5,790
Likes: 450
disconnect all the vacuum lines and cap each port on the intake manifold, then it the problem persists, you can look elsewhere. spray ether around the intake manifold and such. When you pull the vac line off the intake for the FPR, make sure fuel isnt pumping out due to torn diaphragm.