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Rough idle / Stalling in fact was a bad PCM (4.7L)

4K views 7 replies 4 participants last post by  Big Blue 
#1 ·
Over the past couple months my jeep started running super rough. It really happen as temps warmed up above 80 this summer. So, basically would drive to work in the a.m. have no issues at all with the Jeep. Leave work to go home, 30 min. drive 3:30 pm most days. About 20 min into the drive I would get a really bad sputter on acceleration and sometimes stall out at red lights. After a few bad stalls I started to diagnose via this site and youtube etc...

Most obvious to me and looking back at past car issues, I immediately went to the plugs a coil packs. Replaced all eight. Although the engine definitely was firing better the sputter and stall did not stop on the hot days. (Total:$150)

Next, being hopeful that I was not going to have to go through one of these dealership nightmare stories I keep reading over and over again with this model Jeep, I replaced the battery. My battery was old and I figure hell, weak battery can cause all kinds of issues($150)
still no luck same issue persist.

Ok... so what's next that wont cost me a thousand dollars? start checking sensors and replace TPS($30) because I read one thread that said this was the issue for the owner. Still.. NO luck. At this time I'm freaking out because I'm really left no option but to go to the mechanic.
My mechanic is great and super helpful. Also has the full Snap-on diagnostic equipment you need to run live diag. when the car is running. If you are dealing with similar issues I suggest finding a mechanic with this equipment. Anyway, mechanic gave it a run through and the diag. came back with a mis-fire code in every cylinder... not good. He explained to me that it would be nearly impossible for this to happen mechanically or at least he never seen it. 1,2,3 different cylinders sure. All... no way. This is what led him to the conclusion of a BAD PCM. He then explained that the only way to get a working updated PCM that will 100% work for your car is to go to the dealership.Because I was getting ready to spend lord knows how much at the dealer, lukily mechanic did not charge. (I dropped a case a beer of later on)

So here I am $350 in give or take and now HAVE to go to the dealership.
At the dealership I explained the whole story and provided print out of Diagnostics from my local mechanic. They responded "we will need you to o.k. at least 2 hours of diagnostic time at $120 / hr." So with little choice I did that. They called a couple hours later and confirmed again it was in fact the PCM. They ordered the part from factory in ATL and installed. I picked my car up the next morning. PCM install from dealership $800.

I just took a 10 hour round trip with the Jeep loaded to the max pulling a pop-up camper through SC with outside temps 100+ at times and my Jeep did fantastic.
3 weeks its been now, Jeep runs better than ever. Hope this may help someone in the future. Cheers!
 
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#2 · (Edited)
Thanks for the write-up @Dadwagon85. Glad you got the problem fixed. You say you were in SC. Did you by any chance go to Myrtle Beach?

.
 
#3 ·
Over the past couple months my jeep started running super rough. It really happen as temps warmed up above 80 this summer. So, basically would drive to work in the a.m. have no issues at all with the Jeep. Leave work to go home, 30 min. drive 3:30 pm most days. About 20 min into the drive I would get a really bad sputter on acceleration and sometimes stall out at red lights. After a few bad stalls I started to diagnose via this site and youtube etc...

Most obvious to me and looking back at past car issues, I immediately went to the plugs a coil packs. Replaced all eight. Although the engine definitely was firing better the sputter and stall did not stop on the hot days. (Total:$150)

Next, being hopeful that I was not going to have to go through one of these dealership nightmare stories I keep reading over and over again with this model Jeep, I replaced the battery. My battery was old and I figure hell, weak battery can cause all kinds of issues($150)
still no luck same issue persist.

Ok... so what's next that wont cost me a thousand dollars? start checking sensors and replace TPS($30) because I read one thread that said this was the issue for the owner. Still.. NO luck. At this time I'm freaking out because I'm really left no option but to go to the mechanic.
My mechanic is great and super helpful. Also has the full Snap-on diagnostic equipment you need to run live diag. when the car is running. If you are dealing with similar issues I suggest finding a mechanic with this equipment. Anyway, mechanic gave it a run through and the diag. came back with a mis-fire code in every cylinder... not good. He explained to me that it would be nearly impossible for this to happen mechanically or at least he never seen it. 1,2,3 different cylinders sure. All... no way. This is what led him to the conclusion of a BAD PCM. He then explained that the only way to get a working updated PCM that will 100% work for your car is to go to the dealership.Because I was getting ready to spend lord knows how much at the dealer, lukily mechanic did not charge. (I dropped a case a beer of later on)

So here I am $350 in give or take and now HAVE to go to the dealership.
At the dealership I explained the whole story and provided print out of Diagnostics from my local mechanic. They responded "we will need you to o.k. at least 2 hours of diagnostic time at $120 / hr." So with little choice I did that. They called a couple hours later and confirmed again it was in fact the PCM. They ordered the part from factory in ATL and installed. I picked my car up the next morning. PCM install from dealership $800.

I just took a 10 hour round trip with the Jeep loaded to the max pulling a pop-up camper through SC with outside temps 100+ at times and my Jeep did fantastic.
3 weeks its been now, Jeep runs better than ever. Hope this may help someone in the future. Cheers!
This reiterates a point I tell a lot of our new members;

As much as people hate to shell out the money to go to the dealership, sometimes you have to bite the bullet; A lot of times you can do more harm than good trying to troubleshoot, diagnose & fix the issue yourself, unless you are a certified mechanic.

Glad to hear that your XK is in tip-top shape again.
 
#4 · (Edited)
As much as people hate to shell out the money to go to the dealership, sometimes you have to bite the bullet; A lot of times you can do more harm than good trying to troubleshoot, diagnose & fix the issue yourself, unless you are a certified mechanic.
The only dealership I had successfully diag anything correctly failed to make sure they had a TC seal before cracking it open, then the seal was back ordered and they kept the truck for 3 weeks.

Not to mention the factory service manual itself has failed me at least once already when trying to diag a 4wd issue.

I could have bought my own Snap-on scanner and STILL saved money vs what the dealer wanted to charge to solve that 4wd issue, and all that was actually needed was a multimeter, some common sense, and a new T-switch.
 
#6 ·
I wish I had a single Jeep dealership experience across this entire country that allowed me to share a glimmer of your faith, Blue. I really do.

On the other hand, I have 2 independent shops I would trust with my families safety in a heartbeat, neither of which are where I currently live.

I'll take mine in to the dealer for key/computer issues after it's already been diagnosed by another shop or myself. Money well spent, in my opinion.
 
#8 · (Edited)
I wish I had a single Jeep dealership experience across this entire country that allowed me to share a glimmer of your faith, Blue. I really do.

On the other hand, I have 2 independent shops I would trust with my families safety in a heartbeat, neither of which are where I currently live.

I'll take mine in to the dealer for key/computer issues after it's already been diagnosed by another shop or myself. Money well spent, in my opinion.
Well fortunately @Aerogt01, I have had several good experiences, once I found the right dealership. Finding a good reliable dealership is the key.

Good, reliable FCA Dealerships are not Unicorns, they do exist. You just have to do your homework, which might entail traveling a little further than you would like to. It doesn't even have to be a dealership, an honest, competent & reliable independent shop is just as good.
 
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