[msnowdon]

Searching through forum after forum, thread after thread but not sure what to do.


First, I have a 2008 Commander Sport 3.7L with 103k miles.


Ive been wracking my brain trying to figure out this issue. A few months ago, my TPS, Airbag & Check Engine light were all on. I was able to get the airbag light to go out by checking/cleaning all connections under the seats and replaced the fuses which seemed a bit corroded. All air pressure is fine so I assume the TPS light is due to a faulty TPS valve.


I am getting a P0300 code (random misfire) but no cylinder code. I'll drive the Jeep and it will be fine. I'll go to drive it again shortly afterwards it will through the check engine light and run really rough. Lately it now seems to be sluggish and then all of a sudden the power will kick in. Someone posted on another forum that he noticed it seemed to shift between gears alot especially going up hills. Never thought much about it but mine does as well. I usually manually downshift it a gear to keep some power but driving through the hills of Vermont last year I really noticed it had no power. Sometimes I will also smell gasoline but it goes away.


Things I have done:
- Put new NGK Iridium spark plugs
- Replaced all coil packs

- Tested the battery
- Replaced a broken ground strap ( the one that attaches to the exhaust, frame and transmission,)
- Cleaned electrical connections
- Replaced transmission coolant lines and had a dealer check the fluid level
- Recently changed out the Iridium plugs for the original copper plugs. In doing so, I noticed I didnt tighten the plugs down as much as I should have. I blew compressed air into the holes to remove any dirt as recommended by the service manual. When I did that to cylinder 3, some oil came splashing back up at me.


- Known fixes, but not sure where to start:


- Air Intake sensor
- Mass Air meter sensor
- Throttle position sensor
- Crankshaft position sensor
- Camshaft position sensor
- Oxygen sensors
- Fuel pressure
- Vacuum leak
- Fuel injectors
- New PCM

- And so on.....


I didnt know if someone should suggest where to start since its semi intermittent and seems to be more when Ive driven it and it starts when i go to drive it again shortly afterwards.



Confused and fed up with this issue.

 

[Big Blue]

@msnowdon; I can't help you much with the P0300 code short of advising you to go to a shop or dealer with a real OBD-II scanner and have all the DTC's pulled along with the information that comes with them and see what that tells you; This thread my point you in the right direction;

https://www.jeepcommander.com/forums/58-diagnostic-trouble-codes-dtc/43218-p0300-random-misfire.html

The TPM sensor can be triggered by more than just low tire pressure; the individual TPM sensors all have their own self-contained batteries and if the battery dies, that sensor can no longer check in with the TPM system and will trigger that annoying orange light to go off; I honestly don't know off-hand if the batteries can be replaced or not; If not, the TPM sensors themselves are pretty cheap and you can pick them up off of amazon or e-bay, I believe Doorman is the company that makes them and there are probably others. You also have a TPM sensor in the spare tire - which a lot of people seem to overlook when trying to troubleshoot their TPM sensor system.

As far as the constant downshifting, that's probably due to your Hill Start Assist / Hill Descent Control assuming that you have this feature and I believe almost all of the different XK trim packages do regardless of the power-train you have; If you question whether you have this feature or not, it would be listed on your factory build sheet - if you don't have one, I can tell you how to get one, it's easy enough. If your Hill Start Assist is on, you will tend to downshift much more often, particularly if you are towing under load. You can do away with the excessive down-shifting by just turning it off; If you go to your EVIC and toggle through all of your personal settings, when you come to the correct sub-menu, you will have an option to just turn it on or off by pressing the buttons on your steering wheel like you would do to change any other setting in your personal settings menu.

 

[consumedbywater]

TPS and airbag lights are typical on these Jeeps, and I wouldn't be concerned about those at all. Even just a water bottle rolling under a seat and touching an airbag harness is enough to set the airbag light off.

The P0300, rough running, lack of power, and downshifting all are consistent with an engine problem, though I'm sure your transmission service didn't hurt. An intermittent misfire typically does lead to a gasoline scent, so that's consistent as well.

Unfortunately, a P0300 is tough to diagnose; engines don't typically have a way of knowing whether combustion is happening in a given cylinder apart from feedback from the spark plug and injector. This means that you could be having a misfire in a specific cylinder, but the computer has no way of knowing which cylinder so it throws a P0300.

I'd start by running an injector cleaner through your gas tank and looking for a vacuum leak if you've got the tools. Obviously you've got spark sorted out, and typically I'd expect to see more codes if a sensor was having problems, so I'd start with the basics and make sure you've got good fuel and air supplies. You can also read the spark plugs to see if there's an obvious problem cylinder; given the oil in cylinder 3, you may want to start there.

 

[msnowdon]

A couple of more questions:


If I disconnect the harness to the mass air intake sensor while it is running, wouldnt I notice a change in the idle? It made no effect what so ever.


Also, is checking the battery voltage with a multi-meter tool enough or is there a more extensive test? Weird thing I noticed is that I get corrosion on the positive post only. Never the negative post.


Thanks


Mark

 

[Big Blue]

A couple of more questions:


If I disconnect the harness to the mass air intake sensor while it is running, wouldnt I notice a change in the idle? It made no effect what so ever.


Also, is checking the battery voltage with a multi-meter tool enough or is there a more extensive test? Weird thing I noticed is that I get corrosion on the positive post only. Never the negative post.


Thanks


Mark

You can drive to any Auto-Zone or Advance Auto Parts and they will test your battery for free.

 

[msnowdon]

"As far as the constant downshifting, that's probably due to your Hill Start Assist / Hill Descent Control assuming that you have this feature and I believe almost all of the different XK trim packages do regardless of the power-train you have; If you question whether you have this feature or not, it would be listed on your factory build sheet -"


Hi Big Blue,


I went through the EVIC and Equipment Listing Sheet. My vehicle doesnt seem to have Hill Start Assist/Hill Descent Control. It does have Electronic Stability Control, Four Wheel Traction Control & Speed Control. Looks like Im one control short

 

[consumedbywater]

If I disconnect the harness to the mass air intake sensor while it is running, wouldnt I notice a change in the idle? It made no effect what so ever.

Also, is checking the battery voltage with a multi-meter tool enough or is there a more extensive test? Weird thing I noticed is that I get corrosion on the positive post only. Never the negative post.

In theory, disconnecting the sensor should kill the engine if it's functioning properly. If you can disconnect it with no changes, then the computer is likely not getting a good reading from it and is substituting preprogrammed values instead. However, I'm no expert on the 3.7, so I'm just going off my experience with other engines.

As far as checking the battery, you probably should get it tested at an auto parts store. A multimeter can tell you the voltage which is great for checking things like the alternator or detecting a battery that won't hold any charge, but you won't typically see something like a dead cell.

 

[msnowdon]

In theory, disconnecting the sensor should kill the engine if it's functioning properly. If you can disconnect it with no changes, then the computer is likely not getting a good reading from it and is substituting preprogrammed values instead. However, I'm no expert on the 3.7, so I'm just going off my experience with other engines.

As far as checking the battery, you probably should get it tested at an auto parts store. A multimeter can tell you the voltage which is great for checking things like the alternator or detecting a battery that won't hold any charge, but you won't typically see something like a dead cell.

Went I went home for lunch today, I was looking through the EVIC for that hill assist option Big Blue mentioned. Anyway I noticed it did give the P0113 code from disconnecting the IAT while running this morning even though I didnt notice any idle change.



I'll have to get the battery tested like you both suggested. I dont know if its true or not but I read a post somewhere that if it has a bad cell, it will have corrosion on the positive post which mine does. Nothing on the negative post.


My daughter's battery went bad just over 3 years old. It was a Diehard Gold. I was pissed to find out they dont prorate anything for at least up to 5 years. Only a 3 year warranty and then you are out of luck. Batteries used to last at least 5 years. Anyway, I was going to put an Optima or one of the new AGM type batteries in but they are all over $200. I know only a few companies actually manufacture batteries so I shopped around. I ended up buying one from Walmart. Not only was it less expensive, it had more CCA and carried a 3 year full replacement + 2 year prorated (5 year warranty) which is better than any of the Diehards now.



I wont buy another Diehard again. With Sears closing so many of its stores, it would be a pain to get it unless you get it from Amazon.com anyway.

 

[Big Blue]

Went I went home for lunch today, I was looking through the EVIC for that hill assist option Big Blue mentioned. Anyway I noticed it did give the P0113 code from disconnecting the IAT while running this morning even though I didnt notice any idle change.

I'll have to get the battery tested like you both suggested. I dont know if its true or not but I read a post somewhere that if it has a bad cell, it will have corrosion on the positive post which mine does. Nothing on the negative post.

My daughter's battery went bad just over 3 years old. It was a Diehard Gold. I was pissed to find out they dont prorate anything for at least up to 5 years. Only a 3 year warranty and then you are out of luck. Batteries used to last at least 5 years. Anyway, I was going to put an Optima or one of the new AGM type batteries in but they are all over $200. I know only a few companies actually manufacture batteries so I shopped around. I ended up buying one from Walmart. Not only was it less expensive, it had more CCA and carried a 3 year full replacement + 2 year prorated (5 year warranty) which is better than any of the Diehards now.



I wont buy another Diehard again. With Sears closing so many of its stores, it would be a pain to get it unless you get it from Amazon.com anyway.

Corrosion is merely an indicator; It doesn't necessarily have to have corrosion on the positive terminal to have a bad cell.

I'd definitely get that battery tested, sooner rather than later.

 

[msnowdon]

Corrosion is merely an indicator; It doesn't necessarily have to have corrosion on the positive terminal to have a bad cell.

I'd definitely get that battery tested, sooner rather than later.

I did have the battery tested. It tested fine.


I replaced the ambient air sensor, the IAT sensor and the MAP sensor. I also got new Mopar O2 sensors. Took a look at what Im dealing with. Two seem easy to get to. The other 2, not so much. While I was inspecting them, I sprayed them with penetrating oil.



I just saw your link to the diagnostic software you purchased. It came up in yesterdays email summary. From the quick look I gave it, it looks better than what Im using. May also invest in a new code scanner. My current OBDII scanner is a Forseal Wi-Fi scanner.

 

[BadJuju]

Have you rechecked all your new sparks? I put in iridiums a few months ago, at the gap specified by the manufacturer, and found I needed to increase the gap in order for it to work properly.

 

[msnowdon]

Have you rechecked all your new sparks? I put in iridiums a few months ago, at the gap specified by the manufacturer, and found I needed to increase the gap in order for it to work properly.

I did actually. When I went back to the stock plugs, I pulled them out a week later, rechecked the gap and torqued them all. The gap is supposed to be .043" but I could not find any gauges that had .043" as a measurement. I went with the next closest which was .044" I dont like to use those round ramp style gauges.

 

[msnowdon]

So Im just about finished replacing my oxygen sensors. I just need to re-install the left front fender liner which I removed to access the wiring harness. Also ordered the scan tool and software that BigBlue was mentioning.



Should know this weekend if it helps my misfiring issue. Already replaced the plugs, ambient air sensor, IAT sensor, & MAP sensor.


Unfortunately I found a tear in the seal that connects my front drive shaft to the transfer case which is leaking grease and grease is leaking from my front shocks. Some refer to them as struts but from what Ive read, they are actually coil over shocks.

 

[Up4XK]

Unfortunately I found a tear in the seal that connects my front drive shaft to the transfer case which is leaking grease and grease is leaking from my front shocks. Some refer to them as struts but from what Ive read, they are actually coil over shocks.

They seem like struts to me. Struts are a structural part of a vehicle, shocks are not. Coil over shocks just give larger payload capacity. If you remove a shock the vehicle will remain at the same height, there is always some other spring for the wheel that has a shock . If you remove a strut the suspension will hard bottom out. It doesn't matter if the strut is componentized, it is installed as one unit. It's that single unit and the only spring for that wheel that makes it a strut and not a coil over shock with a coil on steroids.

 

[msnowdon]

I finally have had some time to drive the Commander after replacing the oxygen sensors, MAP sensor, Ambient Air sensor, IAT sensor, spark plugs & coil packs. I mean i did test drive it but my wife takes it most of the time and said it has been fine. I took it on the highway today and noticed the transmission wasnt kicking down correctly. It was acting weird when trying, like bogging down and causing the Check Engine light to come on.


When I got home I finally got to play with the Appcar DiagFCA software I purchased. Had no problem getting it installed and connected. Im just not used to having access to all this information. A stored DTC for a misfire on cylinder 3 showed up but wasnt active. Does that mean it didnt throw the light? That was the only DTC it picked up. I was getting confused with the Live Data feature. It has Misfire History Count for cylinders 1-4. What happened to 5 & 6? The software is up to date and shows as a 3.7 Jeep Commander. Also I know what clearing DTCs does but what exactly does Reset ECU ( I think thats the button, I dont have the software open in front of me.) Is that a good thing to try and when should you try it?


Going back to the Live Data in the Diagnostics tab. How does one know which options to check off? I tried checking all of them off for the PCM module just to see what I got for data but it was a pain. I didnt see a select all option, just the option to hide was isnt selected.


The "How To Use It" is okay for getting started, even with it's typos and "English is a Second Language" feel to it but it it doesnt dive into any details. Most of it is giving me the definition of the terms being used.


I do like the software and the programmable features are really cool. I just need to understand it better. I dont want to go screwing something up by accident. And Im still not sure if its misfiring or not. I did clear the stored DTC to see if anything is logged the next time it happens.



Going to play around with it again tomorrow. It was hot when i tried this afternoon and I was getting eaten alive by mosquitoes this evening.

 

[Big Blue]

I finally have had some time to drive the Commander after replacing the oxygen sensors, MAP sensor, Ambient Air sensor, IAT sensor, spark plugs & coil packs. I mean i did test drive it but my wife takes it most of the time and said it has been fine. I took it on the highway today and noticed the transmission wasnt kicking down correctly. It was acting weird when trying, like bogging down and causing the Check Engine light to come on.

When I got home I finally got to play with the Appcar DiagFCA software I purchased. Had no problem getting it installed and connected. Im just not used to having access to all this information. A stored DTC for a misfire on cylinder 3 showed up but wasnt active. Does that mean it didnt throw the light? That was the only DTC it picked up. I was getting confused with the Live Data feature. It has Misfire History Count for cylinders 1-4. What happened to 5 & 6? The software is up to date and shows as a 3.7 Jeep Commander. Also I know what clearing DTCs does but what exactly does Reset ECU ( I think thats the button, I dont have the software open in front of me.) Is that a good thing to try and when should you try it?

Going back to the Live Data in the Diagnostics tab. How does one know which options to check off? I tried checking all of them off for the PCM module just to see what I got for data but it was a pain. I didnt see a select all option, just the option to hide was isnt selected.

The "How To Use It" is okay for getting started, even with it's typos and "English is a Second Language" feel to it but it it doesnt dive into any details. Most of it is giving me the definition of the terms being used.

I do like the software and the programmable features are really cool. I just need to understand it better. I dont want to go screwing something up by accident. And Im still not sure if its misfiring or not. I did clear the stored DTC to see if anything is logged the next time it happens.

Going to play around with it again tomorrow. It was hot when i tried this afternoon and I was getting eaten alive by mosquitoes this evening.

Hey @msnowdon; Do you have any updates on this?

I'm curious as to what you did - or did not find......

 

[msnowdon]

Hey @msnowdon; Do you have any updates on this?

I'm curious as to what you did - or did not find......

I thought everything was good but the misfire code came back. This time it told me it was at cylinder 3. I swapped the coil packs between cylinders 1 & 3 to see if the problem followed it and it did so I bought a new coil pack. I dont know if it was defective from the start because Ive been troubleshooting this for a while now. I originally bought NGK coils figuring the Mopar plugs are actually NGK. but I ended up replacing it with a Mopar one and the misfire seems to have gone away.



Now every once in a while I'll get an Oxygen sensor code. Off the top of my head I think it's P403. I know its post catalytic converter. Maybe I didnt tighten them down enough but they are all new genuine Mopar O2 sensors.


My next issue is that I have a leaking front strut/shock, call it what you will. I have Bilstein 5100s in the rear but I read several forum posts regarding the front ones and decided against them for the front. It has no lift and the shock starts with a little bit of lift. And the adjustable feature doesnt look that strong so I want ones with no lift and non adjustable. I think I read that you are using 4600s in the front. I also read that someone's 5100 had blown out and Bilstein wouldnt cover it since it's not listed for a Commander. I also read bad things about the preloaded struts.


Right now Ive been busy with my 2000 WJ. My gas filler neck had rotted and the overflow tube fell off. I could smell gas and traced it down to that. Also the fuel tank skid plate is falling apart from rust. I purchased a new neck hoses and skid plate. Started this past weekend but has been a real pain in the butt. There is so much rust under there. Two of my mounting bolts broke and now I have to drill them out but the frame looks very weak in some areas. I was able to remove the old skid plate without disconnecting the tank by holding it up with my floor jack and jack stands and ripping apart at the old skid plate.While I was under there I noticed the long brake line that runs from the front is rusted is several spots and its just a matter of time before that needs replacing. If I didnt have so much time & money invested in it, Id throw in the towel and get rid of it.

 

[Big Blue]

I thought everything was good but the misfire code came back. This time it told me it was at cylinder 3. I swapped the coil packs between cylinders 1 & 3 to see if the problem followed it and it did so I bought a new coil pack. I dont know if it was defective from the start because Ive been troubleshooting this for a while now. I originally bought NGK coils figuring the Mopar plugs are actually NGK. but I ended up replacing it with a Mopar one and the misfire seems to have gone away.

Now every once in a while I'll get an Oxygen sensor code. Off the top of my head I think it's P403. I know its post catalytic converter. Maybe I didnt tighten them down enough but they are all new genuine Mopar O2 sensors.

My next issue is that I have a leaking front strut/shock, call it what you will. I have Bilstein 5100s in the rear but I read several forum posts regarding the front ones and decided against them for the front. It has no lift and the shock starts with a little bit of lift. And the adjustable feature doesnt look that strong so I want ones with no lift and non adjustable. I think I read that you are using 4600s in the front. I also read that someone's 5100 had blown out and Bilstein wouldnt cover it since it's not listed for a Commander. I also read bad things about the preloaded struts.

Right now Ive been busy with my 2000 WJ. My gas filler neck had rotted and the overflow tube fell off. I could smell gas and traced it down to that. Also the fuel tank skid plate is falling apart from rust. I purchased a new neck hoses and skid plate. Started this past weekend but has been a real pain in the butt. There is so much rust under there. Two of my mounting bolts broke and now I have to drill them out but the frame looks very weak in some areas. I was able to remove the old skid plate without disconnecting the tank by holding it up with my floor jack and jack stands and ripping apart at the old skid plate.While I was under there I noticed the long brake line that runs from the front is rusted is several spots and its just a matter of time before that needs replacing. If I didnt have so much time & money invested in it, Id throw in the towel and get rid of it.

As far as the front shocks/struts go, you're correct, I have the Bilstein B6 4600 front shock absorbers (Part # 24-186797) they are non-adjustable. I've had them about 3 years now and have had no issues with them to date - even with the Superlift and the 33 inch tires. I'll probably look at upgrading them sometime in the next year or so, but, they have been good to me.

As far as your 2000 WJ goes, I know how it is when you have so much time, money & effort invested in something that you don't ever want to throw in the towel, but at some point, you have to look at the larger picture. If the rust is set in that bad - and it sure sounds like it is, you might be better off cutting your losses now - rather than blowing $1,000 or $2,000 and who knows how many hours of labor, just to keep her going on life support.

 

[msnowdon]

As far as the front shocks/struts go, you're correct, I have the Bilstein B6 4600 front shock absorbers (Part # 24-186797) they are non-adjustable. I've had them about 3 years now and have had no issues with them to date - even with the Superlift and the 33 inch tires. I'll probably look at upgrading them sometime in the next year or so, but, they have been good to me.

As far as your 2000 WJ goes, I know how it is when you have so much time, money & effort invested in something that you don't ever want to throw in the towel, but at some point, you have to look at the larger picture. If the rust is set in that bad - and it sure sounds like it is, you might be better off cutting your losses now - rather than blowing $1,000 or $2,000 and who knows how many hours of labor, just to keep her going on life support.

I know what you mean. Its just that I cant afford a new car at the moment. I refuse to pay thousands of dollars on something that has over 100k miles either. The Commander is our "new" vehicle but thats now 11 years old and has 106k miles. That one was mostly preventive maintenance jobs but now it's starting to need things replaced. And to top it off my daughter has a 2003 Liberty but it only has 64k miles. Its been a great first Jeep for her and and rides better than mine. She is currently studying abroad, so I am using it while mine is apart. So the other day I when I was driving it, I heard a horrible noise while bearing right around a turn. I take a look underneath when I get it home and it looks like the left lower ball joint is bad. After doing some research I find that there was a recall on them in 2003 and a newer recall in 2006. We didnt own it then but records show as having it been completed. I did read that the work is guaranteed so I called a dealer and they basically laughed at me stating that it would be long past any warranty period. I figured it was worth a shot. I wasnt planning on doing any major work to that this year and am not going to have the time to get it done before its too cold outside.



Seems like I just cant win.

 

[Big Blue]

I know what you mean. Its just that I cant afford a new car at the moment. I refuse to pay thousands of dollars on something that has over 100k miles either. The Commander is our "new" vehicle but thats now 11 years old and has 106k miles. That one was mostly preventive maintenance jobs but now it's starting to need things replaced. And to top it off my daughter has a 2003 Liberty but it only has 64k miles. Its been a great first Jeep for her and and rides better than mine. She is currently studying abroad, so I am using it while mine is apart. So the other day I when I was driving it, I heard a horrible noise while bearing right around a turn. I take a look underneath when I get it home and it looks like the left lower ball joint is bad. After doing some research I find that there was a recall on them in 2003 and a newer recall in 2006. We didnt own it then but records show as having it been completed. I did read that the work is guaranteed so I called a dealer and they basically laughed at me stating that it would be long past any warranty period. I figured it was worth a shot. I wasnt planning on doing any major work to that this year and am not going to have the time to get it done before its too cold outside.



Seems like I just cant win.

I know what you mean brother, life just has a way of gut-punching you at the most inconvenient times.

Well, if it was me, I'd roll-up your sleeves and see if you can't get the ball-joint taken care of on your daughter's Liberty.

Do you know anyone that could maybe give you a hand? I wouldn't think a replacement ball-joint would cost that much if you can try & tackle it yourself with an extra pair of hands.