Vacuum Hose Diagnosis

[Brett486]

So I have a high idle problem, and while I think this is mostly due to a loose

throttle body spring, i also think that the fact that my vacuum hose lines are

held together in the middle by duct tape could also be a factor.

 

Engine bay:

 

 

Duct tape connection:

 

 

So my question is, If I replace both vacuum hose harnesses, will that help the idle out?

 

Parts:

Rockauto #46003

Rockauto #46004

- or -

NAPA #7151366

NAPA #7151367

 

Also, is this easy to DIY at home (aka plug n' play), because I see what looks like

rubber cement around the connection to the valve cover and I'm not really sure what

it is or if it's important.

 

Thanks a lot guys.

-Brett

[cruiser54]

Possibly, but no guarantees. If you suspect vacuum leaks, spray the suspected areas with throttle body cleaner with the engine running. Idle speed will change when you hit a leak.Then you'll know the answer. Could be a bad TPS, someone messed with the screw on the throttle body that they weren't supposed to, bad IAC......

[ParadiseMJ]

There are alot of vacuum problem areas that will negatively affect performance, but that particular one, while it will lead to an inspection or smog fail is unlikely to cause running issues, or an out of control idle. Surprisingly it's usually the small hoses on the driver side (with the exception of the brake booster vac line) that can cause havoc.

 

Like Cruiser mentioned, the IAC, as the name implies OR a larger leak like an intake manifold gasket will give you fits.

 

I found out a long time ago that most people ignore their vac lines until something goes haywire. Since there is so much going on under there run by or affected by vacuum. At the junkyard I've seen some pretty questionable vacuum fixes. From tape,which might look like it fixes the line but denegrates fairly quickly, to multi splicing, to replacement with too soft or the wrong diameter hoses.

 

Vacuum line is cheap insurance. If you have any compromised vac lines...REPLACE them with new hose of the right diameter. Replacing a 1/8" id vac line with 1/2" heater hose thinking that "more is better" screws up the whole system, sucking too much and not leaving any vacuum "volume" for other important lines.

 

This, mind you is all from personal experience, I'm not a mechanic. I'm just an old geezer working on my Jeeps in the back of the house. I don't know the engineering of it all, just what has worked for me and what I see on other questionably "modified" systems.

[Guest]

While the "Macgyver'd" hose may not hurt actual performance right now, it will lead to the valve cover intake system getting clogged, which WILL affect performance down the road; but nothing quite substantial as causing high idle. Had the same "Duct-tape" fix on my own truck, and after replacing nearly all the PCV system, the truck ran noticeably different than before; but that was because it was in pretty lousy shape when I finally got it; so anything I did was an improvement. :shake:

 

Fix that hose; and while you're at it, I would clean out the line going from the back of the valve cover to the intake manifold. Possibly even give the baffles inside the valve cover a good cleaning.

 

The lines are pretty plug 'n' play, but sometimes with old age, they become very brittle and like to break into many little pieces; make sure nothing drops into the rockers, if you can help it. :thumbsup: