1993 Jeep Grand Cherokee Rough Idle

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DEEPONE3
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I have a 1993 Jeep Grand Cherokee Laredo with 183,000 miles and the 5.2L motor. Sometimes when I start it, it feels like the motor is missing, possibly not running on all cylinders. Other times it starts up perfectly and will run great for awhile, then it experiences a lack of power, cuts out and lopes on idle, down to 500 rpm on tach. The other day, it started great, ran great into town, then started missing, loss of power, etc. Got so bad when I accelerated, the steering wheel was shaking badly. Limped home. Parked it. Today, it starts fine, went around the block, no problems, runs normal, engine sounds and feels good and normal exceleration ! I am afraid to drive it right now because I don't know when or where it will start doing it again! I have only owned it for a month, but it came with excellent maintenance records. I tried the on/off/on/off/on watch engine light and count how many times it flashes for code number, but it only flashes 5 times and then 5 more times. What does that mean, code 10 ? Well, the codes I downloaded start at 11.....Any help you can give will be appreciated and I am giving a donation! Great service! Thanks, Vance.
Feb 15, 2007 at 9:14 AM
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DEEPONE3
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I could really use your help with this. :)


https://images.2carpros.com/forum/automotive_pictures/59500_f8ff_12_1.jpg

Oct 20, 2019 at 9:25 AM
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RELLIKNIKCUF
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Hey deepone3,

That is actually a code 55 which just states that their are no more codes. If that is the only code you get, then there are none. I would try checking the plug wires. If they look old or dirty, try changing those. They are pretty cheap. After that I might try checking the spark plugs and coil. Let us know if this helps.

Steve
Oct 20, 2019 at 9:25 AM
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DEEPONE3
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Steve,

If it was plugs, coil, wires, etc. it would be doing it all the time, right? It seems to only occur when the Jeep is warmed up, say after 10-15 minutes of driving!
Oct 20, 2019 at 9:25 AM
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RELLIKNIKCUF
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Maybe, once electrical "stuff" gets warmed up, it's resistance changes and just that little bit on a part that is already close to failure can cause it to fail. It can't hurt to check them out, especially with that many miles.

If you have these maintenance records, check what has been done to it in the last couple of years.

Also, the PCM uses different sensor signals to adjust air/fuel mixture when it is warm as opposed to when it is cold. But if a sensor was bad, you would be getting some trouble codes. I'm surprised there are none with a problem that bad.

Check the wires and such. If they all check out, let it idle and see if you eventually get a trouble code.

Let us know how it goes.
Oct 20, 2019 at 9:25 AM
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DEEPONE3
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Ok, gonna check the stuff you mentioned out! It was tuned up 3 years ago with Platinum plugs, silicone wires, cap and rotor and 02 sensor.
Oct 20, 2019 at 9:25 AM
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2CARPRO JACK
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Whenever tuning your vehicle, use OEM parts. Cheaper parts are just that. Never use Bosch Platinums, although they are less expensive, they are in my opinion the worst plug out there
Oct 20, 2019 at 9:25 AM
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DEEPONE3
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I guess I am going to end up taking it in to the mechanic who has worked on it for 10-15 years! He was tghe one who put the "champion platinum plugs" in it 3 year's ago! Although my Brother says Champion plugs are now crappy too!
What kind do you recommend?
Thanks, Vance.
Oct 20, 2019 at 9:25 AM
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RASMATAZ
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Have your mechanic check the fuel system thoroughly.
Oct 20, 2019 at 9:25 AM
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DEEPONE3
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I will have my mechanic check the fuel system and in all probability, it also needs a tune-up. Thanks for the help and I will leave my comments after the appointment tomorrow.
Oct 20, 2019 at 9:25 AM

Suggested Repair

Code 55 means no stored trouble codes. Inspect the plug wires, spark plugs, and coil, since heat can make weak ignition parts fail intermittently, and prefer OEM plugs over inexpensive platinum plugs. Also have the fuel system checked thoroughly and review recent maintenance.

Conversation Summary

The owner of a 1993 Jeep Grand Cherokee with a 5.2L engine reported intermittent misfiring, power loss, and a low, loping idle, usually after the vehicle warmed up. The key-on flash test produced code 55, which means no trouble codes are stored. Advice was to inspect the plug wires, plugs, and coil, use OEM ignition parts rather than cheap platinum plugs, and have the fuel system checked thoroughly.

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