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  #1  
Old 05-29-2011, 01:07 AM
idlewyld89 idlewyld89 is offline
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Smile High RPMs on neutral, possible vaccum leak?

Hey everyone, happens to be my first post!

I just recently bought a used Ranger (2003 2.3L 4cyl) and it just developed a small RPM issue. I'll do my best to be verbose:

When I start the engine, the RPMs are very slow to settle down. Starts out at about 2k and works its way down to ~800 over the course of about a minute. This isn't too abnormal and isn't the real issue.

When I hit the gas, still in neutral (or even in gear, for that matter), the RPMs obviously go up. However, they hang around 1500 for just a second or two, before dropping back to the regular ~800/900.

What I have done so far:

I disassembled the throttle body and cleaned it out. Note that I did not replace any of the gaskets for the TB, I simply took a drop of olive oil and ran it over the existing gasket to "reseal" it. Took a look at the TPS, dosen't look overtly damaged, and the fact that the truck accelerates alright tells me that it is likely not my main issue, if at all. I took off and looked at my IAC valve, and it looked a bit dirty, but I was told over at the local parts store it is highly likely not to be the problem, as the car does not stall. I did not clean the valve.

Also, when I hit the throttle from within the engine compartment, there is a hissing sound apparently coming from the throttle body/manifold cover area. Just off sound alone, it appears that is where it's coming from, however I cannot locate any leak with plain soapy water.

I'm thinking it must be a vacuum leak, but I just cant find it???

Now, mind you, the issue did improve after I removed and cleaned the throttle body. Before, it was revving up to 2k RPM before dropping back down to the normal ~800/900 RPM. Not sure if that was coincidence or if the cleaning actually helped that much.

This truck has been my first foray with auto mechanics. I've generally got a knack for this sort of thing, but when you don't know the nature of what you're working on (i.e. the rules of the game) its a bit harder to play.

Anyways, suggestions are obviously welcome. Would appreciate any past experiences with similar issues.

Thanks,
Idlewyld89

PS: Figured it was fitting that my user name reflect my first issue with my truck... hopefully that doesn't turn out to be horrible luck

Last edited by idlewyld89; 05-29-2011 at 01:15 AM.
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  #2  
Old 05-29-2011, 05:42 AM
ddunfee ddunfee is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

Well I have only owned one ranger but what you are describing sounds normal to me. Does this affect the drivability?
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Old 05-29-2011, 06:47 AM
STL STL is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

Just try to clean the IAC and see if that changes anything. Just because it doesn't stall doesn't mean it dont need to be cleaned.

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Old 05-29-2011, 09:07 AM
idlewyld89 idlewyld89 is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

@ddunfee: the reason I know that it's not normal, and sorry that I forgot to mention this, is that I did get a check engine light with a code for too high of RPMs. That was back when it was revving up to 2k RPMs... it hasn't thrown a code since, but the symptoms are largely the same, just more mild.

@STL: yeah, thinking back I should have just bought the electronics cleaner... it just sounded too good to save the $6 and just use soapy water to find the issue, haha.

Anyways, I'll be working on the problem again today. Perhaps an update will be in order this evening.

Thanks all!

PPS: also, my MPGs are pretty low compared to what they should be. The truck is rated for 29mpg highway, and I've actually been getting something like 21mpg... thats more evidence of a vacuum leak, from what I've been told.

Last edited by idlewyld89; 05-29-2011 at 09:10 AM.
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Old 05-30-2011, 03:04 PM
idlewyld89 idlewyld89 is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

Update:

Alright everyone, so I just finished cleaning out the IAC valve with some sensor cleaner and took it for a testrun. The entire problem seems to have scaled down yet again. Remimber that I said initially, it would rev up to 2k RPMs before droping to the customary ~900 RPMs. Then, after cleaning the throttle body (valve and housing only, not the manifold) it reved up to 1500 RPMs befor dropping. Now, after having cleaned the IAC valve, it only revs up to approx. 1k RPMs before dropping a bit lower than before (approx. 750 RPMs) at stopped idle.

However, there is potentially a new symptom. As I was taking it for a test drive, when I was coming to a stop at a light, it died... no studdering, no rough idle, it just turned off. It started right back up, and did not do it again for the remainder of the ~15min drive. It had done that once before, back when the problem was worse, and it was reving up to 2k RPMs.

I should mention that, through this entire situation, once the engine drops to the correct RPMs (~800-900), idle is NOT rough at all. It is very smooth, and has been that way ever since I bought the truck.

It seems that as I further clean the throttle body and its components, the issue continues to clear up. However, whats up with that stall?

Any ideas are greatly appreciated!

Last edited by idlewyld89; 05-30-2011 at 06:33 PM.
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  #6  
Old 05-30-2011, 03:30 PM
terryduanemiller terryduanemiller is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

common EGR failure.. you can block the EGR vaccum line with a BB (yes like a BB gun) drop the BB in the fitting and press the vacuum back on the EGR. The BB is to large to fall in to EGR and to large to get sucked in to the line..
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Old 05-30-2011, 06:21 PM
idlewyld89 idlewyld89 is offline
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Default Re: High RPMs on neutral, possible vaccum leak?

@terryduanemiller: thanks for the suggestion. I don't suppose you'd happen to know where the EGR valve is located on a 2003 2.3L 4cyl ranger? I've got a few pictures of the valve, so I'm just gonna start investigating. Hopefully it's not super difficult to get at.

EDIT: I'm not actually sure my truck has an EGR valve, as it doesn't show up on the vacuum diagram under the hood.

Last edited by idlewyld89; 05-30-2011 at 07:00 PM.
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2003, idle, leak, throttle, vacuum

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