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Blinking CEL and "shaking" car.

8K views 43 replies 9 participants last post by  rreh 
#1 · (Edited)
Hi Guys,

I've been reading this forum since I got my Silver 2006 in March and now it's time for my first thread.

I have a really strange issue that has occurred a couple of times and I haven't found any threads with the same issue.

I start the car in the morning to take my kid to daycare and it's running fine. The drive is only a couple of minutes so the engine is still cold when I shut it off. Leaving the kid and firing up the car again to go to work and the issue starts. I can hardly accelerate och it feels like the whole driveline is shaking/grinding at the same time as the CEL flashes. This is around 20 mph and goes on for maybe 20 seconds and if I accelerate a bit more the CEL and grinding goes away and the car runs like it should.

Each time this has happen the procedure has been the same. Home -> Stop at Daycare -> Issues on my way to work -> Works fine rest of the day.

Anyone have a clue? I hooked up my Intune but no codes logged.

The only mods I have is a CIA and the 91oct CIA tune from Diablo and the car is at 75k miles.
 
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#5 ·
Just drive it until it breaks, better yet when the CEL starts blinking do a couple WOT. That might help.

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Lol yes will do that, good suggestion.

I don't know what to tell the shop though and it's hard for them to find anything when there are no codes and the issue only occurs occasionally. I was hoping for some suggestions on where to start looking.
 
#7 ·
The issue occured again on my way home today and this time I stopped the vehicle, pulled out my Intune and got a code: P0300 Random/Multiple Cylinder Misfire Detected. Cleared the code and tried to repeat the issue but the car ran smoothly.

So I'm down to this:
Cold start trigger the issue (sometimes), a warm engine doesn't and it's not caused by WOT specificly. If I don't stop during the issue it goes away and no code are logged.

Before this happened the first time the car was sitting for one month during my vacation and the only thing I've done since I got home is to install a new Air Intake sensor.

Next thing might be to return the stock tune and see what happens.
 
#15 ·
I will take it to a local mechanic but they didn't have time until the 23:d so I will contiune to search for possible google-solutions.

Since it all started the issue has changed. Now the engine misfires a couple of seconds after start up (when idle) and not after a couple of minutes of driving. It disappears after a minute or so and will not repeat itself until the car has been sitting for many hours.

I also noticed that my coolant was really low so I most likley have leak somewhere. Could that be connected to the misfire?

I cannot help thinking this has to do with the car been sitting for a month in really shitty mountain weather since it was fine when I left it.
 
#16 ·
Dude, pull a spark plug. It's easy. A swivel joint, extension, ratchet and spark plug socket with the rubber insert. Remove coil packs stick the socket in there and take one out.


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#17 · (Edited)
I know but I have to get the tool first. I live in an small mountain village so I have to order everything online


----- 1 hour later ------


Ok so feeling a bit stupid about not checking the plugs yet I gave the local gas station a go for a tool and yeeeey they got one.

Happy me removes the first coil pack, sliding the tool in and gnnnniih, gnnniiih gniiiiiiiih.... Nothing. Wtf it doesn't move at all. On it again with full power: nothing. I'm about to pop a vain in my neck before giving up and getting a beer instead.

I think I need a better tool, what are you guys using? See attachment for my tool.
 

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#23 ·
I've pulled 13 of 16 plugs and they all looked good (see img). The three closest to the front of the driver side was blocket by the fusebox and some other plastic stuff, any tips on removing that? Could not figure it out :)

Strange thing: After checking the plugs I fired her up and this was the first time this week without misfire. I've started her two times more during the day and no misfires at all.
 

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#28 · (Edited)
Over time, a spark plug's gap naturally opens up and that can easily cause a misfire.

I suggest swapping all the plugs as a good measure.



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The plugs was changed about 15k miles ago so if feels unnecessary to change them if they're good. Like I wrote earlier the misfire has stopped since I filled up the coolant tank from almost empty so right now a change of spark plugs would tell me nothing until it (hopefully not) starts to misfire again.

I have to install a new starter, find/fix the coolant leak and change the fluids in the axles and TC this month so I'm hoping the plugs are good for now. Parts and labour are really expensive here in Sweden so all of the above are draining my wallet. :surprise:

Edit: As the car had been sitting for a month before the misfire started I also filled up with a fresh tank of gas + a bottle of Injector Cleaner and I'm now down to a half tank since. So the only things I've done som far is: Coolant, fresh gas, Injection Cleaner and checking 13 of 16 plugs and misfire gone since Sunday.
 
#29 · (Edited)
Blinking CEL and "shaking" car.

Coolant should not cause a misfire issue. Generally it's fuel/fueling or an ignition issue.

15k does not warrant a plug change but I would check the gaps since you have them out.

When you provide limited information we can only give you a response based off of the info at hand.


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#30 ·
Coolant should not cause a misfire issue. Generally it's fuel/fueling or an ignition issue.

15k does not warrant a plug change but I would check the gaps since you have them out.

When you provide limited information we can only give you a response based off of the info at hand.


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Sorry about the limited info, I didn't know myself until yesterday when I went through the old reciepts. I've only owned the car for three months.

Good thing though is all the info from you guys so if/when the issue returns I know where to start looking. It's nice that it's gone for now but it bugs me not knowing why the issue disappeared :)
 
#34 ·
So the misfire has been gone for two weeks but returned yesterday. Checked the codes again and now I also have the "P0152 - 02 Sensor Circuit High Voltage (Bank 2 Sensor 1)". I managed to do some data logging with my Intune during the misfires but this is way over my Google skills.

Do we have any Data Viewing Ninjas at the forum? Check this screen cap: https://vimeo.com/172389290/7d2c07ad6b on my logging. I'll be forever grateful if this helps me with the issue. :x
 
#35 · (Edited)
I just realized my previous link (to Vimeo) didn't work because of some forum setting so have a look at the attached image instead. From what I have red on various forums my Long Term Fuel Trim & Short Term Fuel Trim values are way off and I've also noticed that the misfire only occurs under 3000 rpm. Above 3000 rpm my fuel trims are within -5% and + 5%.

Plugs and gaps are looking good and coil packs and wiring looks good. I'm going to check the o2 sensors tomorrow and if they are looking good the Jeep are going into the shop next week to check for fuel pump issues, vacuum leaks etc.

Before this all started I replaced my stock muffler for a Magnaflow and that's the only thing i've done besides replacing a broken IAT-sensor and installing a K&N CAI and I ran the CAI for a couple of weeks without any issues so I doubt that's the cause. Annoying problem!
 

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#36 ·
Time for an update.

The misfires are still there and I'm getting a couple of other codes from time to time. I took the car to a shop two weeks ago but the misfires was (of course) not present when they had a look at it. They did check for vacuum leaks though but couldn't find any.

Some other interesting observations:
* The random misfire is on Bank 2 only.
* The symptoms are getting worse with low gas, no misfires at all when tank is full.
* Code P0175 showed up once (System Too Rich Bank 2).
* Code P0152 showed up (Sensor Circuit High Voltage Bank 2 Sensor 1).
* Code P0153 showed up (Oxygen Sensor Circuit Slow Response Bank2, Sensor1).
* Code P0430 showed up (Catalyst System Efficiency Below Threshold Bank 2).

Anyone have ideas what would cause only Bank 2 to misfire? Could it be the o2 sensor? When the misfire is present the Bank 2 Sensor 2 are reading 0 volts and are then getting back to normal when the misfire stops.

It's also very strange that the symptoms are getting worse when I'm low on fuel. A couple of days ago, when the tank was almost empty, the misfire ONLY occurred when the car was in Park or Neutral. It was idling very rough but stopped as soon as I switched to Drive. Filled her up to 50% and the symptoms are back to "normal".

The shop first suspected the cat to be bad but there are no signs of that (smell, loss of power etc).
 
#37 · (Edited)
Blinking CEL and "shaking" car.

Did you try moving coil packs? Maybe an injector issue. Could also be a bad 02 sensor.

That doesn't necessarily explain full/empty gas tank relationship. Maybe fuel pump related.


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#38 ·
Did you try moving coil packs? Maybe an injector issue. Could also be a bad 02 sensor.

That doesn't necessarily explain full/empty gas tank relationship. Maybe fuel pump related.


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I haven't moved the coil packs since the misfire occurs on all cylinders on Bank 2 (2,4,6,8) so I figured that all of them wouldn't go bad at the same time.

Is it possible to check the injectors by my self? The local shop is closed for a couple of weeks during summer so I'm trying to continue to rule out stuff by my self :)
 
#39 ·
Oh ok. I misunderstood. It is the whole bank that is misfiring. We'll probably not injectors then. No you would have to send them off to be flow tested, but that is probably not it.


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#41 ·
I found another interesting thing today when I was driving around. I recently red about Closed vs. Open loop and the ODB2-software I'm using on my iPhone was able to log these PID's.

The car wasn't bogging much but I could feel that is didn't run 100% smooth so I hooked up the scanner and saw this:

Fuel System 1 Status - Closed Loop
Fuel System 2 Status - Opel Loop Fault.

Maybe I should just order a o2 sensor and hope for the best but I guess that the 02 sensor could have gone bad from the misfires.

Fuel pressure will be checked when the shop opens after their summer vacation.

The positive thing about this is that I've learnt a lot about engines, sensors and fueling. Always something :smile2:
 
#44 ·
Time for an update.

I installed a new o2-sensor on bank 2 four weeks ago and the misfires has been gone since. Unfortunately it seems like the misfire killed my catalytic converter on bank 2 so I need to take care of that soon. Anyone had experience in replacing one cat with a weld in?

Conclusion: The o2 caused the misfire and the misfire killed the cat. I've red hundreds of pages and threads about this and from what I've learnt it could also be the other way around so it wasn't easy to figure it out. I just hope the damn misfire stays away now so I can focus och fixing other things that needs to be fixed :)

Thanks for all the help.
 
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