Multi cylinder misfire

[dgulia]

No fixes so far

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[SJK]

No fixes so far

Mine was fixed. At least for 5 days and counting. Demonstrated cold start at service dealer. No lights, but we both felt engine misfire. Mechanic then discovered stuck vvt on left side of engine. Replaced vvt , lifters and rockers of left side of engine. No more CEL and AS/S functions flawlessly. Also, compression test done and tested within limits. Spread the word . . .

 

[dgulia]

Mine was fixed. At least for 5 days and counting. Demonstrated cold start at service dealer. No lights, but we both felt engine misfire. Mechanic then discovered stuck vvt on left side of engine. Replaced vvt , lifters and rockers of left side of engine. No more CEL and AS/S functions flawlessly. Also, compression test done and tested within limits. Spread the word . . .

Good luck and enjoy

 

[Robicon]

Mine was fixed. At least for 5 days and counting. Demonstrated cold start at service dealer. No lights, but we both felt engine misfire. Mechanic then discovered stuck vvt on left side of engine. Replaced vvt , lifters and rockers of left side of engine. No more CEL and AS/S functions flawlessly. Also, compression test done and tested within limits. Spread the word . . .

Do you know what the compression test results were prior to the repair?

 

[SJK]

Do you know what the compression test results were prior to the repair?

They did not tell me.

 

[ShadowsPapa]

Mine was fixed. At least for 5 days and counting. Demonstrated cold start at service dealer. No lights, but we both felt engine misfire. Mechanic then discovered stuck vvt on left side of engine. Replaced vvt , lifters and rockers of left side of engine. No more CEL and AS/S functions flawlessly. Also, compression test done and tested within limits. Spread the word . . .

I really wish anyone with the issue could read this one. I've been trying in other threads to convince some folks that no, this is NOT a damaged cylinder wall issue on all 3.6 engines in the JT.
There have been some that have been fixed with the PCM update, and some have been fixed with the VVL or VVT system being fixed, some were fixed with those and new lifters throughout. Others insist that theirs HAD to be a bad cylinder wall issues because someone else said so.
This is proof that these are NOT all caused by the same thing.
Same symtoms can be caused by varied issues. So insisting because you have a misfire or a code that you need a new engine is not reasonable.

 

[CCDANIELS]

I really wish anyone with the issue could read this one. I've been trying in other threads to convince some folks that no, this is NOT a damaged cylinder wall issue on all 3.6 engines in the JT.
There have been some that have been fixed with the PCM update, and some have been fixed with the VVL or VVT system being fixed, some were fixed with those and new lifters throughout. Others insist that theirs HAD to be a bad cylinder wall issues because someone else said so.
This is proof that these are NOT all caused by the same thing.
Same symtoms can be caused by varied issues. So insisting because you have a misfire or a code that you need a new engine is not reasonable.

Taking my jeep in on the 23rd for the 4th time, hopefully they will start replacing parts...

 

[ShadowsPapa]

I had an 89 or 90 Jeep Cherokee. Everyone once in a while when driving home on the rural road that had a speed limit of 45, it would feel like the thing hit ice or a slick spot, then it would take off again and be fine. This didn't happen every trip, just sometimes. And in good weather - there was no ice, there were no slick spots, it was a good blacktop road. OVer and over it would act like you had let up, or the wheels had started spinning as if on ice, then take off again.
Took it to the dealer - no codes, it read fine. They ran it, drove it around, found nothing. Of course - it only did this a couple of times a week or so.
It was three trips to the dealer and getting it back finding nothing that I told them - 4th trip - keep it, I don't care if you have it a week. Let one of the mechanics use it for a few days - drive it home to lunch and back, I don't care - just keep it.
2 or 3 days later they got their heads together and figured out what to watch for - still no codes, nothing stored or randomly appearing.
Then it finally did it for them - still not SURE what was going on, they followed their hunch - crank position sensor - the PCM was getting bad info and acting accordingly.
They replaced that sensor and all was fine.
They resolved it with basic troubleshooting skills - knowing the product, decuctive reasoning, whatever. There was no real book to follow, no chart. Prior Jeeps had been RENIX systems to OBD was fairly new to Jeep at that time. (can't recall the exact year, but I'm sure 87 and 88 were RENIX systems)

The moral of the story - too often todahy no one has basic troubleshooting skills. If it ain't in a book or stored as a code, they can't think. That's what's going on in many cases - and to me, ASE certicifation doesn't mean squat. I've run circles around those guys in the past and the tests they used to take, at least a few years ago were basic stuff, nothing that difficult.
Not to diss all ASE techs - some are damned good, but it's not that certification that makes them good - they were good before they got that. It's like a Masters degree - I worked with too many of those folks who couldn't even figure out how to reboot a computer or put gas in thier car. Doesn't teach common sense.

 

[CMac]

Ford makes turds also. So the grass is not always greener.

That...is an irrefutable FACT.

 

[HONCHO]

I really wish anyone with the issue could read this one. I've been trying in other threads to convince some folks that no, this is NOT a damaged cylinder wall issue on all 3.6 engines in the JT.
There have been some that have been fixed with the PCM update, and some have been fixed with the VVL or VVT system being fixed, some were fixed with those and new lifters throughout. Others insist that theirs HAD to be a bad cylinder wall issues because someone else said so.
This is proof that these are NOT all caused by the same thing.
Same symtoms can be caused by varied issues. So insisting because you have a misfire or a code that you need a new engine is not reasonable.

so a stuck vvt does not send a code? a few new engines might get there attention . lol

 

[ShadowsPapa]

so a stuck vvt does not send a code? a few new engines might get there attention . lol

VVT/Valve timing - I'd like to see the sensors for that.......just to know how they detect what mode it's in.
Valve timing would shift the power band, cause poor power when you need it but shouldn't cause a misfire. Just poor performance.
VVL/Variable Valve lift - a cylinder misfire should take place if that's hanging up - it would mean the intake would not be opening far enough. (unless stuck on high lift, then it's your gain, but mpg lost)

 

[HONCHO]

VVT/Valve timing - I'd like to see the sensors for that.......just to know how they detect what mode it's in.
Valve timing would shift the power band, cause poor power when you need it but shouldn't cause a misfire. Just poor performance.
VVL/Variable Valve lift - a cylinder misfire should take place if that's hanging up - it would mean the intake would not be opening far enough. (unless stuck on high lift, then it's your gain, but mpg lost)

Non movement sensor . More wires ,more complexity .more weight . all good . lol

 

[HONCHO]

what about an overly lean tune ? can"t feel a misfire in my JL ,but it sure surges like invisible wind gusts , on an dead calm day .

 

[ShadowsPapa]

Non movement sensor . More wires ,more complexity .more weight . all good . lol

Interesting - a sensor that detects - nothing! More wires - these things don't have nearly enough.
Weight - just have your steering gear replaced. That will take care of a couple of pounds if you feel your Jeep is too light.

 

[ShadowsPapa]

what about an overly lean tune ? can"t feel a misfire in my JL ,but it sure surges like invisible wind gusts , on an dead calm day .

Bad O2 sensor? PCM out of whack.....? Lean will surge like you said.

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