Engine Idle Fluctuates, Low RPM when stopping, Keeps dying - Jeep Commander Forums: Jeep Commander Forum
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post #1 of 9 (permalink) Old 04-05-2016, 06:50 PM Thread Starter
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Exclamation Engine Idle Fluctuates, Low RPM when stopping, Keeps dying

So not sure what is going on with this 07 XK 4.7 V8... but here is my problem...

Had the Jeep die a few days ago while stopping at a red light in the morning. Read online the TPS or IAC is usually the culprit.. so I go to Advance Auto and purchase and replace both... now the thing if anything is worse. It will run, but the RPMs idle at 500 RPM average, and when stopping while in drive or reverse, it dips down to 200-300. Had a alternator/battery test done, and it all checked out (take that test for what it's worth), went back home, un-installed, and re-installed things.. cleaned the throttle body best I knew how, looked for vacuum issues on any hoses, removed battery power to reset.. started it up and it was horrible and kept dying. After a few times started running and was ok... until I turn the AC on high.. then it's like it has barely enough power...

Had to be at work so drove it about 10 miles with AC on low.. didn't die, but I could tell the problem of RPM droopage was still there...

When I got on a backroad with no one else around close to work, I cranked the AC up on high, and as I was coming to a stop sign, I turn signal on, braked, and turned wheel a little bit to prepare my turn, and as I stopped the RPM kept going down to 0 and died... started right back up.

I have tried new IAC, TPS, cleaned throttle body, checked hoses, batt/alt test (good)

What am I missing?

Have an appt on monday at the dealer for the ignition recall, and a computer flash recall for 4Lo I believe that were never done by PO.

PLEASE HELP!
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post #2 of 9 (permalink) Old 04-11-2016, 12:57 PM Thread Starter
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Just an update, it's at the dealership getting recalls done.. and they said there are 3 flashes it needs, but only the 1 is covered under the recall.

I've since tried replacing the IAC and TPS only to have worse results at idle and driving.. so I put what was on it back on. It still dies randomly coming to a stop, usually in the mornings or when first driving it for the day. And for those saying replace the transmission filters, the dealership won't do that. They want to perform a full on system flush, which I don't want. So the transmission for now is being left alone. Hopefully the flashes fix that.

Also for my "check gas cap" / evap issue they said my leak detection pump is bad after performing a smoke test, and will be replacing that. Hopefully that damn check gas cap notification on my screen stays away
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post #3 of 9 (permalink) Old 04-11-2016, 03:09 PM
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Malfunctioning AC can cause the AC Compressor to have so much resistance it can stall out the motor, especially when coming to a stop as the motor goes to idle. Remember, if you have the climate control on "Defrost" it runs the AC on low, I have seen a bad AC system stall a motor coming to a stop with only "Defrost" on. That sounds like what you describe and I think your next step should be to have the AC checked out.


You should be checking for stored fault codes, that is always your first trouble shooting step.


Your dealership sounds like one of the many rip-off dealerships. The FSM doesn't recommend flushes, Chrysler put a TSB recommending against flushing transmissions and most of the vehicle systems. Yet, bad dealerships that try to squeeze every dollar out of their customers, ignore the recommendations and recommend service against what the manufacturer recommends, to make money.


Software updates are suppose to be free once the vehicle is inducted into service. i.e.
  • If there is a recall for a software update, they should do it for free.
  • If you just pull up to the Dealership and tell them to do a software update, for something NOT under warranty or a recall, and that is all you ask for, they can charge you for their time to induct it into service and hook up the tool to do the software update.
  • If you already are having service or recalls done, where they have already inducted the vehicle into service and have hooked up tool already for other issues, they are suppose to do the software updates free of charge.
Hopefully they are NOT charging you for these other software updates.


Personally, I'd just buy the filters and fluid and change the fluid and filter myself on the trans. If you change your own oil and can change a IAC and TPS, you can change the transmission fluid and filters.
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post #4 of 9 (permalink) Old 04-13-2016, 12:36 PM Thread Starter
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Been a couple days since picking up from dealership, and today I noticed the random RPM dip coming to a stoplight.. but it didn't dip enough to stall the vehicle out.. I'm sure if the AC or heat would've been on it probably would've died on me again..

Any chance that my spark plugs may need to be replaced? Haven't checked the condition of them yet. Still no codes or lights
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post #5 of 9 (permalink) Old 04-13-2016, 02:03 PM
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So you have checked for fault codes, doing the key dance, and it didn't return any fault codes?


Yes, spark plug tips erode away with use, this makes the gap grow bigger and the spark to become weaker, it will result in rough idle and running, less power, lower fuel economy, misfires and stalling.


You're owners manual will have schedule stating when they should be changed. I think most Commander's engines its every 30k miles or there a bouts. It is that interval for the V6 (what I have) NOT sure on the V8's, but I think its the same on most years of the V8's.


As well, modern engines are much more precise and accurate than the past, some use alternate current flow schemes for the plugs, and then there are several plugs with new technologies to make them last longer, that aren't compatible with the reverse current flow schemes, etc. Basically, more than a few folks have used another brand of plug, then recommended in the owner's manual and ran into all sorts of problems. So most recommend you just use the exact brand and model plug the engine came with, that is listed in the owners manual.


So, yes, if you're overdue for a spark plug change, that should be your first step in troubleshooting, catch up on all the overdue periodic maintenance, that alone could be the cause of the stalling, and if it does NOT solve, you needed it anyway.
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post #6 of 9 (permalink) Old 04-13-2016, 02:08 PM
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Quote:
Originally Posted by rexx66 View Post
Just an update, it's at the dealership getting recalls done.. and they said there are 3 flashes it needs, but only the 1 is covered under the recall.

I've since tried replacing the IAC and TPS only to have worse results at idle and driving.. so I put what was on it back on. It still dies randomly coming to a stop, usually in the mornings or when first driving it for the day. And for those saying replace the transmission filters, the dealership won't do that. They want to perform a full on system flush, which I don't want. So the transmission for now is being left alone. Hopefully the flashes fix that.

Also for my "check gas cap" / evap issue they said my leak detection pump is bad after performing a smoke test, and will be replacing that. Hopefully that damn check gas cap notification on my screen stays away
So did you discuss the stalling problem with the Dealership service writer? And did you authorize them to troubleshoot and fix it?


Of did you just discuss it and only authorize them to do one or two things they suggested?


I have trouble believing a Dealership, if you told them you had a stalling problem, didn't immediately suggest new spark plugs if you were overdue?


At the same time, I have trouble believing the Dealership would refuse to do a fluid and filter change on a trans just as the manufacturer suggested, and instead insist they will only do it if you pay for a transmission flush, which is against what the manufacturer recommends against.


Sounds like your Dealer is either inept or unethical.
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post #7 of 9 (permalink) Old 04-13-2016, 03:47 PM Thread Starter
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Yes I told them the issues, and told them to try and figure it out, but if they don't see the problem they rule it as "Can't replicate issue" or something to that effect, and say good luck... Lots of shops in this area are lazy which is why I tend to be a DIYer to a point. The PO has randomly swapped out parts I've noticed like the IAC and TPS both looked brand new.. so who knows.. going to pull a coil pack and plug tonight and see how dirty it looks.. will go from there..

Should I go NGK, Champion, something else? for plugs?
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post #8 of 9 (permalink) Old 04-13-2016, 04:19 PM
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Quote:
Originally Posted by rexx66 View Post
Yes I told them the issues, and told them to try and figure it out, but if they don't see the problem they rule it as "Can't replicate issue" or something to that effect, and say good luck... Lots of shops in this area are lazy which is why I tend to be a DIYer to a point. The PO has randomly swapped out parts I've noticed like the IAC and TPS both looked brand new.. so who knows.. going to pull a coil pack and plug tonight and see how dirty it looks.. will go from there..

Should I go NGK, Champion, something else? for plugs?
Do you know how many miles are on the current plugs? How many miles are on the vehicle?


Regardless, considering how eroded away spark plugs, or using the wrong brand of plugs can cause problems exactly like this, I'd consider just changing out the plugs. Never done it on a 4.7L, but the 3.7L is the same design, just 2 cyl less, and I can do the V6 in an hour, the plugs cost like $15. So unless you have some evidence they are the right plugs and have been in less than the change interval, I'd just get a new set of spark plugs and change them.


Check your owner's manual, it will tell your the interval you should change the plugs, and the brand and model of spark plug to use.


I know my 3.7L V6 uses the NGK V-Power. And if I used the NGK single platinum version of that plug, which a lot of auto stores will try to hock you the higher priced plug, I would run into problems 10k miles down the road.


So look up the plug recommended in the owners manual, the brand and model number, and only purchase that brand and model number, do NOT let the parts guy sell you something different.


I can regail you for hours about auto parts and repair guys that think they know everything, but they are totally clueless, they only get away with it because 75% of the people that come in the door are even more clueless then they are.
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post #9 of 9 (permalink) Old 04-20-2016, 10:28 AM Thread Starter
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Exclamation

**UPDATE**

So about a week or so has went by and what seems to have solved my problem was simple as spark plugs... the previous owner apparently never did this as these things were SHOT.. on a few the electrode was so worn down they were flush.. the gap on them all was ridiculous.

As far as the replacements, I followed the specs and went with Champion Copper Plus 439 plugs... They're cheap, and if you know the tricks to Advance's site.. you can get 20% off on in store pickup which makes this an UNDER $15 job (assuming you don't have the Hemi). Champion Copper Plus Spark Plug 439: Advance Auto Parts

So far I've seen no negative effects.. mileage went up a bit from 11.5 to 13-14mpg, acceleration is WAY better, call me crazy but I notice it actually goes when I push the skinny pedal, and most importantly, it doesn't randomly die in the mornings.. why only after I just start it up and get a mile or two in and dies at a light, I don't know.. but the problem has went away.

Only other things that were done were 2 recalls, ignition recall and a final drive flash that fixes the "Service 4wd" notification, and I had a smoke test ran to find my "check gas cap" problem, which upon testing turned out to be my leak detection pump (dealership did this and replaced it, $109 for test, and maybe $30 for parts).

So far things are still going good, anything changes I will update again.
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