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Old 12-28-2012, 09:23 AM   #1
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Talking slight miss at idle and cruising speed

hey guys, new here. thought i'd give it a shot. have jeep wrangler 4.0liter. have a slight miss at idle and at cruising speed(no acceleration). if accelerate , it runs fine. changed distributor cap, rotor, wires plugs, and crank position sensor just as tune up. no check engine light. starts everytime. any help would be appreciated

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Old 12-28-2012, 09:28 AM   #2
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i know i have read all about the different sensors, map, tps, iac, and cam position sensor. was hoping one of ya'll had same problem to narrow it down to the most likely culprit. if could get rid of this little miss, runs great otherwise. thanks again!!!

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Old 12-28-2012, 09:32 AM   #3
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Yours since new or is previous engine work unknown?
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Old 12-28-2012, 07:48 PM   #4
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Could be coil pack (?).
Coil pack on my97 had a crack in it and was producing similar symptoms except it was intermittant (and much worse).
I replaced all the same things you did AND the coil pack, now it's running fine.
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Old 12-29-2012, 06:52 AM   #5
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Thumbs up coil pack

will give it a shot, appreciate the response. there are so many little things that could be wrong, was hoping someone else had same problem. thanks
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Old 01-01-2013, 11:55 AM   #6
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well, been awhile since been on forum, but still have slight miss at idle and constant speed, goes away when accelerate, even if accellerate just slightly. i did notice miss gets worse when in reverse backing up. sprayed wd 40 around intake to insure no gasket or vac leaks, none detected. cleaned iac sensor real good, no change. any ideas? already replaced wires, plugs, crank sensor, rotor button, dist. cap. any dealings with cam position sensor in distibutor? easy to change, but really dont think that is problem. pls help. thanks
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Old 01-01-2013, 11:56 AM   #7
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oh yeah, no check engine light.
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Old 01-01-2013, 12:20 PM   #8
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Did you clean your throttle body?
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Old 01-01-2013, 01:08 PM   #9
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Smile clean tb?

no, didnt clean tb, read where some say take it off, and some say clean it while still on with engine running. what clean it with? carb cleaner? took it down the road and ran it up to 4500 rpms for couple miles to see if would blow out the soot, but didnt help
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Old 01-01-2013, 01:12 PM   #10
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from what i can see with tb on the engine, doesnt look too bad dirty. did spray wd40 into iac on side of tb and cleaned it as best could.
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Old 01-01-2013, 01:21 PM   #11
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have went through several gallons gas from different stations, and 3 bottles of injector cleaner, still have miss. can drive and idle at stop without having to pat gas, or anythg. If sit in shop at idle, there is black carbon exhaust that is on floor from tailpipe. has smell also. i'm sure from burning fuel in cat from running rich

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