Question about 2003 Jeep Grand Cherokee

2 Answers

Several things Please help!!

My warranty just expired and of course the issues now arise. My 2003 Jeep Grand Cherokee 4x4's engine light has come on. Occasionally when I start it it will go up to over 3 rpms and stay there for about 5 minutes. Also when I coast at a slow speed and almost stop it will stall out. It will start back up but runs very rough and the transmission shifts very hard. I took it into a Jeep dealership and they said the code came back as the throttle position sensor but that the problems I am having are more than likely caused by something else as well. I assume they are trying to rip me off because I'm a young female and just wanted your opinion please. My car has 71,000 miles and has had the relay fan switch replaced, passenger window thingy, and has recently had an oil change and they couldn't find anything wrong. Thanks for any and all tips you could give me! I'm broke and can't afford major work!!

Amie :)

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  • maggymay1957 Oct 12, 2008

    my engine is spluttring and the fuel injection light as come on does any one no what this is and is it costly , it a renault scenic 2000 y reg

  • jmacfeet Oct 30, 2008

    I have been having the same problems!!! I have no idea what is causing this! The mechanic has replaced the crank sensor and cam sensor on my '03 GC with 61,000 miles. I had both the stalling and the high rpm on the highway. What did you do to fix this?

  • chalmersjn Dec 23, 2008

    I have the same problem. the fan keeps running and killing the battery and passanger window fell off track just after my warrenty expired!



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My answer:

Hello Amie,

I just dropped you a short post reply on your other posted problem relating to this one I'm now answering, as for some reason I wasn't seeing this original one grouped together for whatever reason. Oh well...

Anyway - this kind of a long reply so bear with me here.

Not sure why no one answered you as of yet, but I will as I've seen this problem, and a few similar "ghost" related problems like this quite frequently.

Jeeps are notorious for rough idling and INJECTOR FOULING problems. That is a given.

Even my little sister's 1988 Jeep Grand Limited had similar problems, and even the rip off dealership couldn't fix the dang problem, and then ripped her off big time to the tune of $500+ for basically doing nothing. Tried to tell her she had the wrong Platinum spark plugs installed, which was total BS!!

About your rough idling, hesitations, and stalling. Here's the straight talk about what no doubt is happening with your Jeep - seeings you only have young mileage of 71,000 on it.

It seems like on many an SUV and esp TRUCKS with the older Ignition Coil Packs and Spark Plug Wires scheme that 60 to 75,000 miles was an average time period to when the spark plug wires would start breaking down.

I had the very same thing happen on my 1993 Ford XPLR - where once it warmed up it started to miss and backfire, and seem to want to stall out when taking off from a standing stop, but ran fine at higher RPM's. Mileage was around 20-22 mpg on the open road with Cruise Control set at 70-75 mph too! On the "preprogrammed or preset PCM computer" COLD circuit start up it ran just fine until after the engine reached it's optimal operating temp, and then the stalling problem would kick in. That was the BIG CLUE right there!

At first I too had suspected possibly the TPS (Throttle Position Sensor) as maybe being dirty or sticky, as the symptoms would be very similar, but even more pronounced and persistent if it indeed was a bad TPS.

I ruled out both the Oxygen Sensors (and they were just fine btw), as I wasn't getting a CHECK ENGINE code for those or even the TPS for that matter. So I knew it was something that wasn't "sensor" related. I thought possibly a bad Coil Pack, but that checked out fine as did the Platinum Spark Plugs I had just recently installed. That only left the Spark Plug Wires as the fault.

Even though Jeeps are notorious for having FOULED FUEL INJECTORS quite frequently - I really doubt that the TPS is your problem.

I highly suspect your SPARK PLUGS ARE BAD! All it takes is 1 bad wire to really break down and the symptoms are very pronounced. 2 bad wires on a V-6 engine like mine, and you really have problems like I even had with backfiring through the intake plenum! Have you heard any backfiring on your Jeep as well? If so - there is your problem!

My 1993 XPLR roughly had 93,000 miles on it when the original factory Spark Plug Wire problem cropped up. For sure I had 1 bad measured wire, and possibly a 2nd bad one as well. The recommended change out period is 60,000 miles, so anything over that and you are on borrowed time as they say. A brand new lifetime warranty $20 Spark Plug Wire set from Pepboys solved the problem. AND - guess what - that new set had a bad wire in it that broke down about 20,000 miles later, so thank God I had the lifetime parts warranty as the 3rd set was free!!

My buddy's Ford F-250 had the same "missing" problem and he bet me $20 that the problem wasn't the Spark Plug Wires. Guess what? Easiest $20 I ever made! New set of lifetime spark plug wires later - END OF PROBLEM - end of story!!

Your TPS could still be slightly dirty, and with a good spray cleaning should improve that original rough idling, hesitations, and stalling problem. If it doesn't then that is not the problem, as many times a CHECK ENGINE light will register multiple Engine Codes, as it did with your Jeep. That is why the even the stupid dealership couldn't figure it out! Go figure huh?

Why the IDLE goes up to ~ 3000 RPM and holds for some 5 mins like you were saying it does is a bit strange as well, as your saying it wants to also stall out when coming to a coast at a slow speed and then almost stalling out at a near stop. I seriously doubt a dirty or bad TPS here at all. That 3000 RPM holding like that is a bit strange to say the least, but it makes sense as my XPLR was doing something similar on HOT startups, as then the spark plug wires were breaking down even more so!

What's probably happening is your bad Spark Plug Wires aren't firing strong enough, and in turn the engine is taking longer to come up to temp, and then playing mind games with the PCM (Powertrain Control Module) computer. Everything has to be working right from not only a Sensor standpoint, but also from a Firing standpoint as well.

So when you have 1 or more bad Spark Plug Wires, which you no doubt do, then it messes everything up. The PCM can only compensate so much and then it goes crazy too!

After all it's not human you know! hahaha

Now granted your FUEL INJECTORS may be a bit dirty as well and I'm recommending that you do the following as well:

Jeeps in general don't have a good track record for great mileage, and rough engine idling is always a clue that your fuel injectors are dirty. All bad Spark Plug Wires aside! Typical on all Jeeps with port fuel injection systems! On Jeeps with dirty fuel injectors your mileage will go way down accordingly and will idle very rough. If your not putting at least a 12 oz bottle of say Walmart brand Super Tech Fuel Injector Cleaner (~ $1 each) in your gas tank religiously every logged 1000 miles, or every 2 tank fill ups, then you are just inviting dirty fuel injectors and POOR fuel economy!

Try to burn good gas in your Jeep as here I use ARCO gas which always has burned great in my XPLR. I never had good luck with EXXON as it tends to FOUL some spark plugs really bad!

If you need help with the brand of Spark Plug Wires let me know, and I'll try and get you the stock # and Mfr's name. They've probably gone up in price since I bought mine so probably expect to pay maybe $25-30 for a set now. Mine were around $15 back then, but that was around 9 years ago!

Let me know if you have a PEPBOYS AUTO or a AUTOZONE parts place near you?

Hopefully this will save you a lot of $$$ and get your Jeep running smooth again!

Take care now,


Posted on Aug 13, 2008

  • Frank JR
    Frank JR Aug 23, 2008

    Hello Amie,

    Any response or reply back here??

    I'm not getting any feedback at all here. I sure wish people posting
    here would feedback to the Experts here as how else will we know what
    is happening with your problem??



  • anna_berg
    anna_berg Feb 05, 2012

    I'm having the same issues and this was helpful! Thank you.



I also have an '03 Grand Cherokee Laredo, and I had the same problem. Fortunately it was still under warranty but I did have to pay $300 for a fouled injector.

Posted on Jul 07, 2008


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