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Old 06-06-2010, 03:18 PM   #1
Join Date: Jun 2010
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Rough Idle And Sputters when Cold

I recently purchased a 97 jeep Wrangler, 2.5, auto transmission,a/c, 133000 miles. I am having a problem with my engine idling rough and sputtering when the engine is cold.

I took it to a mechanic who used a snap-on scanner to diagnose my problem. There where no CEL codes. Everything looked fine. All the sensors appeared to be reading correctly. The only problem he noticed was that when the jeep was started cold, the scanner had a low engine vacuum reading of about 11. After the engine started warming up, the vacuum picked up close to normal and the engine idles much better. Still a little rough but better. He checked the engine for vacuum leaks and said that he could not find any. He claims to have checked it very well.

After his diagnose? he suggested that it was probably an internal engine problem and that I should just put a new engine in it. I'm not sure that I am buying this. Has anyone had an issue similar to this? Can anyone point me in the right direction? Please help.

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Old 06-15-2010, 01:38 PM   #2

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remove the aircleaner, get some throttle body cleaner, spray it into the opening on the side by the throttle body until it runs smooth. YOu'll have to hand rev it with the throttle to keep from dying at first.
I just did this and It solved a similar problem.

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Old 06-15-2010, 02:19 PM   #3
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Pretty close to the same thing on my 97 /2.5.
All codes checked good at Auto Zone's free machine. He told me it was probably a map or Throttle Body sensor starting to go bad if he had to guess. He told me of another place that had a better diagnostic testing device that charged, but said it would probably show up.
I'm trying to run some fuel injection cleaner in it first to see and I "think" it seems to be better.
Keep us posted.
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Old 06-15-2010, 02:47 PM   #4
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pretty common with bad gas... do like mentioned, clean your throttle body and the idle air controller really good and re-assemble. May want to replace the spark plugs as well... Can't hurt to try...

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1994 Wrangler YJ I6 4.0 H/O Auto 3 spd. 4" RC (33x12.5) (15x8) 3:54 Gears
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idle problems , rough idle at start , sputtering , vacuum

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