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Discussion Starter · #1 ·
Hi forum,

Long time lurker, first time poster here.
My 2019 Grand Caravan (70k miles) has rough idle. Pretty much all the time and slightly more in drive or reverse.
CEL was on with "misfire cylinder 2" so I replaced coils and spark plugs. The CEL is gone, did not came back again (for 500+ miles now).

However idle is still rough and quite noticeable.
My next guess is failing engine mounts. Here's a video of the engine when switching between drive and reverse:


That is too much movement, right? Meaning that one of the mounts is bad?
Is there a specific mount that is more prone to failing than the others?

Thanks in advance!
Tim
 

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I watched the video and I wouldn't put my money on or into engine mounts without getting under the van and looking at the mounts directly. I'd want to pry against them directly with a pry bar and look for cracked and broken rubber as well as separation where the rubber meets the metal.

Personally, I'd go after the rough idle alone. Does the misfire go away in any off idle condition? How does the van run under throttle and cruising conditions? Have you scanned for codes again? You can still have codes even without a check engine light on. They're called pending codes. Do you have some kind of cheap scanner that might at least be able to give you fuel trims at idle?
 

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Discussion Starter · #3 ·
I watched the video and I wouldn't put my money on or into engine mounts without getting under the van and looking at the mounts directly. I'd want to pry against them directly with a pry bar and look for cracked and broken rubber as well as separation where the rubber meets the metal.

Personally, I'd go after the rough idle alone. Does the misfire go away in any off idle condition? How does the van run under throttle and cruising conditions? Have you scanned for codes again? You can still have codes even without a check engine light on. They're called pending codes. Do you have some kind of cheap scanner that might at least be able to give you fuel trims at idle?
very helpful, thanks!
I plugged in my code reader and found the following:

None of the voltage readings are stuck at 0v or 1v. But I saw that one o2 voltage reading was constantly at ~0.75V while the other was going up and down.
Does that indicate anything?

Thanks again,
Tim
 

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Your fuel trims and your O2 sensor PIDs suggest that the engine is running well. The van seems like it still has a lot of old technology compared to other manufacturers. The upstream O2 is likely a narrow band sensor and it's supposed to cycle rich to lean. That's what the voltage reflects. The downstream O2 indicates that your catalytic converter is doing its job well. You'll notice that the PIDS say short term and long term 1 or 2. You do the math between short term and long term for bank 1 or bank 2 and the net correction needs to be less than 10% total correction. The PIDs you're showing us are pretty much perfect.

All I've offered so far was the best I could offer from my keyboard. If you want to move forward with your engine mount theory, just make sure you can prove it before you spend money on parts & labor. How does the van feel while driving during acceleration and normal cruising speeds? Does it still feel rough under those circumstances?
 

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A shot in the dark---have you done a compression test--sometimes a weak cylinder will cause rough idle and will go away as engine speeds up while driving--I don't know how your ECM system works if it will show a possible vacuum leak via the O2 reading---intermittent injection operation---a broken vacuum hose/line/fitting may leak on & off depending on it's location---another thing have you tested your wires for positive connections--none loose--broken or wet (water is a SOB when it comes to ignition)--two phases of engine operation one is mechanical other is electrical---I don't know of any computer/ECM--code reader that will pinpoint a mechanical issue--it may lead you in the right direction (or not) to find problem but not absolute--systematic testing of mechanical then electrical is required to eliminate questionable issues---this may be a stretch & don't if this is related but a fellow told me that he was having hell of a time to find ign problems that according to him lead to find iron/metal partials had accumulated around pickup--he claimed that this was his problem distracting the pickup sensor--- don't know if this was actually the problem since he replaced the sensor but he claimed it was---I just checked & it appears there are two type of ign systems so a lot of this info may be weak
 

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Hi forum,

Long time lurker, first time poster here.
My 2019 Grand Caravan (70k miles) has rough idle. Pretty much all the time and slightly more in drive or reverse.
CEL was on with "misfire cylinder 2" so I replaced coils and spark plugs. The CEL is gone, did not came back again (for 500+ miles now).

However idle is still rough and quite noticeable.
My next guess is failing engine mounts. Here's a video of the engine when switching between drive and reverse:


That is too much movement, right? Meaning that one of the mounts is bad?
Is there a specific mount that is more prone to failing than the others?

Thanks in advance!
Tim
 

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If you do decide to replace the mounts, DO NOT USE AFTERMARKET mounts. Had to replace 5 aftermarket mounts on my 2, 2008 Grand Caravans in under 10k miles. Mechanic was able to get parts store to replace 1 of the mounts free, but that 1 failed in less than 3k miles. Best to use mopar mounts, although pricey. Originals went 100k miles before failure.
 

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Discussion Starter · #8 ·
I just did a compression test (dry)
Cylinder 2: 120PSI
all other: 150PSI (+/- 1PSI)

Cylinder 2 is passenger side / front.

I guess that might be the cause?
Bad head?

Thanks,
Tim
 

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It's with in 20% margin so I don't think that's the problem--try it wet & see what you come with--BTW did you ck all vac lines & wiring---something just came 2 mind ck harmonic damper to see if it's loose as in some are internally rubber mounted--the rubber fails and the damper will rotate in/on mount/carrier axis causing imbalance---also have you check your flywheel to see if it's loose---I'm under the belief that the motor is original & was never changed cause if it was & the wrong flywheel was installed that not balance to that specific motor---you know this is something like trying to tell how to cut hair over the telephone
 

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Hi forum,

Long time lurker, first time poster here.
My 2019 Grand Caravan (70k miles) has rough idle. Pretty much all the time and slightly more in drive or reverse.
CEL was on with "misfire cylinder 2" so I replaced coils and spark plugs. The CEL is gone, did not came back again (for 500+ miles now).

However idle is still rough and quite noticeable.
My next guess is failing engine mounts. Here's a video of the engine when switching between drive and reverse:


That is too much movement, right? Meaning that one of the mounts is bad?
Is there a specific mount that is more prone to failing than the others?

Thanks in advance!
Tim
I don't see anything abnormal, either with movement or vibration. If your PCM isn't storing codes for misfires then the engine isn't misfiring. Given these engine mounts can last hundreds of thousands of miles, I seriously doubt yours are bad. If one was bad, it would most likely be either the one at the front or the one attached to the transmission on the right side of the engine/transaxle (not the one under the battery) which is probably the hardest one to get to.
 

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Discussion Starter · #11 ·
Thanks for all the tips!

I did the compression test dry vs wet on cylinder 2 today:
dry: 120PSI
wet: 140PSI

That's too much increase, right?

Btw I checked all vac lines (visual and with starter fluid) and the harmonic damper. All looks good.
 
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