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Discussion Starter #1
Hey guys, I'm writing back with regard to the Jeep I bought recently.

This was a 1-owner "certified pre-owned" vehicle with 85,000 miles which the dealership has been unable to resolve issues they promised to fix; transmission shudder and drivability issues.

My previous post was about the transmission which after the dealership stopped returning my calls I started checking into myself, and found it was 3 1/2 quarts low on fluid. After resolving that I still have an occasional torque converter shudder on slight grades when going from lock to unlock, etc, but otherwise it seems much better. Not sure how that is going to end up yet, time will tell.

The other big issue it has is after driving on the highway for more than 15-20 minutes, and then exiting the highway and going through normal stop then go, the engine stumbles hard then blows out a HUGE cloud of black/gray smoke which takes up to 30 seconds or so to clear out then it runs fine again.

Overall, I've got the engine running pretty smoothly most of the time, but this highway thing is really weird.

The other thing it does, is while driving on the highway, if I have to slow down, then speed back up from say 60-70mph, it will not accelerate AT ALL when the throttle is opened, even at wide open; what it will do, is after wide open, then backing out of it, as I back out of the throttle, it will begin to accelerate almost as if in reverse to the throttle position. In other words, at WOT, there is nothing, but the more I slowly back out of it, it then gradually begins to accelerate back up to 70mph.

Overall, gas mileage is good now, it started at 9-12mpg when I first bought it.

It will get 18mpg at 80mph now (with winter tires on), and around 15mpg combined city/highway, which is about the same or maybe a little better than my previous 4.7L Commander.

I drove 500 miles yesterday and this highway black smoke thing is 100% repeatable.

Any ideas what's going on here?

I really appreciate your thoughts and input!

Mike
 

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Discussion Starter #2
Oh, one other strange thing it did yesterday, while driving up north, up and down moderate grades, it actually downshifted while going down hill with the cruise set at 65mph. I've never seen this happen in any car I've ever driven.
 

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Was the hill a steep grade? it may have done it to control your speed. as for the Black smoke. Is it losing oil? Are you on or off the gas when it smokes/. What motor do you have?
 

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Discussion Starter #4
It doesn't appear to be losing engine oil, I just had the oil changed yesterday so I will monitor it closely.

It's the 4.7L.

If I exit the freeway and stop at a gas station for example, it will blow out a big cloud of smoke when I restart it and also when I begin driving again.

If the engine hasn't been shut off after exiting the freeway, it will do the hard engine stumble then blow out the smoke, then run fine again after about 30 seconds.

The smoke looks to me to be carbon or unburned fuel building up in the intake manifold or injectors or both, or maybe even in the exhaust somewhere.

If so it must be really plugged up...

Thanks again!

Mike
 

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Discussion Starter #5
The hill was in Grayling Michigan on M-72 where they put in "passing lanes," so moderately steep grade. I just don't recall either of my previous two 4.7L Commanders downshifting like that on the same roads; the rpms jumped from around 2000 to 3000 pretty abruptly.
 

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Discussion Starter #6
It just seems really odd that the gas mileage is so much better now but still having this problem with the black smoke.

One other thing: before I bought the Jeep when I looked it over I saw the air box spring clamps were missing, and there was some debris in the bottom of the airbox. I had them replace the clamps when I bought it and when I got it home I took the airbox apart and cleaned everything out as best I could, and put in a new filter. It does not appear to have been driven on gravel or dusty roads from the condition of the underneath and the exterior, but this did cause me some concern as I have no idea how long the airbox clamps had been missing, or how much junk may have gotten into the engine.

So much for "fully inspected certified vehicle I guess!"

I did ask them yesterday to re-check the trans fluid to be sure I had it right and they said it was right at the proper level on the dipstick, which was after I added the 3 1/2 quarts of ATF-4.

This has been so disappointing since the Jeep literally looks brand new inside and out, and with the low mileage, it seemed like a great car to buy after my '08 got wrecked.
 

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Um, I think the 2009 are electronic throttle body.
It sounds to me with the down shifting and almost like dumping of fuel it's getting the wrong signal and thinks you're flooring it or something.

But I really don't know. You've got that 16 spark plug design too.
Plus I'd Assume it'd send a Code for the tb and accelerator not matching.

Other stuff to think about 02 sensors, they can affect fuel mixture.
Did the PO put a performance adapter on the PCM?
Does it look like any performance modes were removed?

Most concerning is it being so low on transmission fluid and the dealer not catching it. If you have a warranty it may be worth paying a mechanic with a good reputation to go over it and find what dealer ignored. Ought to be some kind of lemon law too I'd think.


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Discussion Starter #8
Yes, it's the 16 plug design. They assured me they would change all the plugs before I bought it since there was no service record that said they had ever been replaced.

All they said they did after was change the number 7 plug and injector due to the MIL they told me about when I went to look at it the first time. They also replaced a hub/bearing, and a ball joint, and brake pads before I bought it as part of their "certified pre-owned" inspection.

How they never caught the low trans fluid is beyond me, maybe the tech was just checking off boxes on the inspection sheet without really doing all the work. The trans oil pan leak was not enough to lose 3 1/2 quarts unless it's been leaking since new, it was just a dribble. I think someone must have serviced the transmission pan and never got the oil level correct in the first place. It never set any "trans over temp" fault code since I bought it.

I doubt the Jeep was ever run hard and it has zero modifications to my knowledge. Overall, it's just too clean and low mileage; my guess is whoever owned it before didn't drive it much and didn't drive it hard at all. Maybe it has done this for along time and they just babied it for years, which is what I did when I first started experiencing the issues with the trans and the engine and the black smoke.

It has not reset any fault codes since I had it back in to the dealer within an hour of when I bought it and it started doing the hard stumble & black smoke thing.

I've driven about 3000 miles since then.

Seems really odd that it can be doing all these crazy things and not setting any fault codes.
 

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Despite being overburdened by sensors there is a ton of faults which do not trigger a code.
My sister has a newer Hyundai that started one morning running completely out of time and too rich. We all happen to be right there when it happened, no codes were recorded.
Next restart it was fine, has not done since.

Your commander seems like it is dumping fuel when this happens, which makes me think the electronic throttle is sending the wrong info. Also because of the down shifting.
Seems like the PCM thinks you're putting the hammer down when you coasting to a stop or getting going again.

But leaking injectors could cause the rich black smoke. But IMO not the down shifting.
Maybe cylinders not firing, not firing on all the plugs.
Does that year 4.7 have the fuel saving feature turning off cylinders when cruising on the hwy?

Possibly bad transmission or PCM.
I'm out of my depth just a few ideas.



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Could it be a sticky injector?
 

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Does that year 4.7 have the fuel saving feature turning off cylinders when cruising on the hwy?

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I have the same engine though mine is a 2008 4.7L.

They do not have the hwy fuel saving turn-off cylinder feature.

There isn't anything about these tanks designed to save fuel....LOL.
 

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Only fuel I save is the fuel I 'rescue' from the gas station prison.

I rescue a lot of gas all the time....
 

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Have you reset the ECU recently?
 

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here's a couple things to think about, the "highway fuel saving feature" as far as I'm aware is only available on the 5.7 Hemi, furthermore, only on the '09 and '10 model. Also, try your side spark plugs, the real PITA ones to get to. they're Iridium or Platinum (don't remember) spark plugs that are supposed to be changed at 90k miles. I know you're not there yet, but again something to think about. The other spark plugs, the easy ones to get to are supposed to be changed every 40k miles. You are over that if they had been done on time in the past. As far as downshifting when going downhill, I used my '08 4.7 to tow 2 and a half tons 3600 miles in less than 72 hrs, I had my tow mode activated, so this may not apply to you, but somehow the jeep was able to determine I was going downhill and engine brake for me by shifting down. I would go down a scary incline (as it was my first time towing anything) and stay steady at 55mph with my foot nowhere near the brake. It was wonderful. It might do the same outside of tow mode. I'd test it for you but my jeep is under surgery atm. with your throttle response, I really have no clue. grounded wiring? bad TB? bad sensor? computer fault? I'm sorry I can't help you there, actually try cleaning the MAP sensor.
 

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The fuel saving mode - MDS (Multi Displacement System) is only on the 5.7 Hemi and on all years of the Commanders. The trans will downshift when going down hill if the Tow/Haul is activated OR if your cruse control is on.
 

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Discussion Starter #16
I did reset the ECU a month ago. I will reset it again.

I was going to do the upper bank of plugs, already have them, but maybe I'll just have the dealership do all 16 of them. On my last Jeep, the coil pack boots were fused to the spark plugs on the top bank, and it was a real disaster trying to change them at 30,000 miles.

I pulled a couple of the plugs in front of this engine to inspect them a couple of weeks ago and they didn't look bad, but might as well start fresh!

It seems the engine is really plugged up with carbon or oil sludge or both.

Sometimes it runs perfect, and other times it just stumbles and belches smoke, so that appears to be a sign that the issue is intermittent which makes it that much more difficult to diagnose and fix.

Last week I pulled off the OEM junk Forteras and put a set of Blizzaks on it. Crazy thing is my gas mileage went up noticeably by 2mpg (same thing it did on my last Jeep), and the ride and handling are also dramatically improved, as well as road noise. Go figure!
 

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If you want to try to clear up the cylinders, You can run some marvel or Seafoam through the intake or vacuum line, and shut the engine off as its pulling it in, that way some sits in the cylinders. Wait 10-15 minutes while it breaks it down, and then start the motor back up. Does the engine make any noticeable ticks or knocks? Has the oil gone down since your change>
 

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Are you sure MDS was on all years Hemi? I could've swore both VVT and MDS were applied in 2009 for the commanders

Edit: i just looked it up, probably should've done that first. You were right, the "highway fuel saving feature" or "MDS" was available in all 5.7 hemis only in all years of the commander. I'm glad i know that now and haven't gotten my ECU tuned yet. I'll have to make sure that I get that tuned out.
 
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