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Post-Starting Engine Rumble

Old Aug 6, 2010 | 01:59 PM
  #1  
MK262MOD1's Avatar
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From: FT BRAGG, NC
Default Post-Starting Engine Rumble

Hi All,

I have a 2007 Wrangler X, auto, with about 27k. It's pretty much stock right now.

In about 1 out of every 30 starts the engine will catch fine, then rumble deeply and the RPMs will drop slightly but only for a few seconds and then everything is fine.

Has anyone else had this happen and/or have any suggestions for diagnosing the problem?


Also, every once in a while it seems like that starter can't get going and takes a few tries/seconds more than usual to start the engine. Any ideas for that one?

Thanks in advance, pretty new to the Jeep and don't have a lot of time on it yet.
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Old Aug 6, 2010 | 02:09 PM
  #2  
Alec's Avatar
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From: Houston, TX
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I wouldn't worry about it.

The first symptom is probably just the computer adjusting the idle; possibly the weather changed. As long as it stabilizes quickly and you don't have any other issues (and it's only at startup), I'd say it's normal.

Is the second one usually after it's been sitting for a day or two? Probably just needs a few seconds for the fuel pump to catch up. Try turning the key to "on", count to 2 or 3, then start. This lets the fuel pump build up pressure in the system before cranking.

These are 2 issues that could be the start of something, or could be nothing. Extremely hard to say which if those are the only 2 issues you have.
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Old Aug 6, 2010 | 03:10 PM
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From: Southern California
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I think what you may be hearing is the power steering pump. Mine grumbles a little when first started cold then settles in.

Flash
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Old Aug 6, 2010 | 08:11 PM
  #4  
MK262MOD1's Avatar
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From: FT BRAGG, NC
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I'll check to see if it's just after it's been sitting a bit. Normally I only notice it in the mornings after it's been sitting overnight but it's very irregular.

I'll also try getting the fuel pump up to speed before I start the Jeep. Would that also explain the lowering in RPMs?

It's been hot here, 100F + so that may explain the computer problem. If you have anything else I can check for please let me know!
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