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Something odd happening with the idle RPM

peter683

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Hi Guys
just noticed this today.. when stopped at a light with the transmission in drive, I hear a slight tick noise from the right hand side of the dash possibly firewall? and the RPM fluctuates about 50 to 100 rpm up and down up and down?? any ideas??
 
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2stroke

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Could you try and listen under the hood to find a more specific area? The tick could be something as simple as something caught in the fan blades. The first thing that popped into my head, although unlikely, is timing chain. A loose timing chain makes a tick, and often causes a strange idle. Do you have any engine codes?
 

natenkiki2004

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Chances are it's not a timing chain. They're very strong and well-designed in these OHV's. They're hydraulically adjusted with a ratcheting mechanism so even if you lose oil pressure, they stay tight. Mine had about 227,000 miles on it and looked fine. I only opted to replace it as preventative maintenance, and I didn't know what I'd find going into it.

Maybe if oil changes didn't happen frequently enough and you're up around 300,000 miles, might be something to think about.

Chances are, it's something in the valvetrain, lifters or excessive clearance or both. But definitely try to narrow it down.
 

2stroke

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I've never had a timing chain fail either.
 

peter683

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Thanks guys I dont have a code reader so will have to try that trick and counting the flashing engine light for the code. Not sure if related but I also seem to get the rmp racing a bit to say 1500 or so as I feel it on the road when I am on the brakes at a light or something. Doesnt happen often just not sure if its related.. I wish I could afford repairs but I cant at the moment being out of work..:thumbdwn:
 

2stroke

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does it race when you switch the controls to max A/C or OFF?
 

peter683

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Havent tried that. It happened yesterday when I pulled in the parking lot and had my foot on the brake with it in gear and the rpm was pushing 1400 and when I put it in park with my foot off it raced up to 2000 before I shut the key off.. When I came out half hour later or so it was fine all the way home?
 

2stroke

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Sounds like a good old vacuum leak to me. The reason I say to try max A/C is it runs of vacuum and some of the line is in the cab where you can't see. All the other lines you can check visually. I don't think the tick is related.
 

peter683

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Damn.. I Wonder if the vacuum hose that I posted about last year has broken again.. Thanks for the tip I will take a nosey under the hood when the weather dries up a bit.:thumbsup:
 

peter683

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Update

Hi guy's I checked on the passenger side all along the bulkhead and I cant find anything wrong. The vac hose is still attached but I did find something.. Standing at the drivers side fender if you look down behind the grill there is a square container of sorts with two round removable caps on it with two rubber hoses coming off of the container. One hose crosses up and over the left side rocker cover and runs towards the upper front part of the intake manifold?? the other hose has come off where it attaches as there is remains of a rusty pipe in the end of the hose...? Any ideas where this secondary hose runs to???
Thanks for the help as I do not have the manual for the truck as it was removed while having the engine changed...
 

GreenMountain4x4

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Is it the charcoal canister that you are talking about? If so it should go back to the fuel tank if it is not the one going to the intake. Pictures would help as well.
 

peter683

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Thanks Greemountain, Yes that is the canister... It switches from a rubber hose to a metal one but I cant see where it goes?
 

GreenMountain4x4

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It goes to the top of the fuel tank
 

2stroke

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one hose goes to the bottom of the throttle body
 

peter683

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Interesting.. the still attached hose seemed to run towards the front of the engine?
 

GreenMountain4x4

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That one goes to the intake, attaches on the underside of the throttle body <-as 2stroke already said!
 
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acschilling

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Your explorer is idling at 1400-2000 rpm..that would be a wicked vacuum leak. I don't know how the A4LD works since I have a M5OD and they sound awful, but does the auto tranny use vacuum at all? Do you push the brake in to switch to park? No idea. These are rhetorical-just throwing out ideas. Or maybe any one of the numerous sensors monitoring idle are acting up.
 

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