Chasing down engine vibration/judder

Hi everyone,

Apologies for the duplicate thread, if possible can admins delete my old one and keep this one it seems I posted it in a less than ideal place

I’m chasing down a slightly lumpy/rough idle on my 2006 Discovery 3 4.4. It doesn’t sound like a stumble or miss but the shake/vibration is felt through the car every so often. It’s not consistent and is felt at idle. Visually like this ___—________—__—_____-. I a consistent vibration through the car at around 1k rpm but this is consistent and feels inline with the engine rpm and is mot a random vibration.

Note that this vibration is felt in neutral, park, drive when stationery. When in drive the vibration feels reduced and it also seems to be more prominent when cold. I have zero vibration or roughness when driving the car is buttery smooth.

Steps I have currently taken: Cleaned MAF, cleaned throttle body, cleaned EGR, replaced air filter, reset engine adaptations

I have JLR SDD and here’s some data I have collected from the car:

MAF 6g/s

No misfires on misfire counter

No fault codes

RPM stable and not fluctuating more than 10-20rpm

Intake cam timing bank 1: 41.532*

Intake cam timing bank 2: 45.778*

Car is running in closed loop

Long term fuel trim: B1=1.56% B2=0%(B2 seems to not change on graph?)

Short term fuel trim: B1=-3.13% B2=-4.69%

PCV is shown to be operating, but unsure if it’s doing what it’s supposed to do

Can anyone spot anything wrong with the above data read? Or does anyone have any suggestions?

I’m trying to do as much diagnostic as possible rather than throwing money at it till something sorts it. Can provide any more data at request I’m just not sure how to interpret the rest

I’m leaning on it at this point being engine mounts to be honest, engine itself seems to be running quite happily.

I would have posted your last line as my first line!

Stanleysteamer said:

I would have posted your last line as my first line!

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Haha yeah I was sort of hoping it wouldn’t be this! Bit of a pain for a driveway mechanic and will probably have to go to a shop

Seems to be worse on the cold start but I guess the engine is thrashing about a bit more when cold.

HACKCHILD said:

Haha yeah I was sort of hoping it wouldn’t be this! Bit of a pain for a driveway mechanic and will probably have to go to a shop

Seems to be worse on the cold start but I guess the engine is thrashing about a bit more when cold.

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Maybe @gstuart will know.

Resetting adaptions isn't always a good move, as the the ECM has taken many hours of running to set them. The adaptions learn the engine characteristics as it wears, so clearing then puts the ECM to an "as new" setting, which won't suit an engine with many miles on it.

The MAF reading looks low to me. I'd expect to see much more than 6 g/s.
The timing between banks seems off too, I'd expect to see a couple of degrees variance at most.
The long term trims are ok, but the shirt terms seem at the higher end of acceptable.

Just my opinion of course.

Edit. The MAF readings are probably correct, I'm thinking of diesel MAF throughput, which is much higher than a petrol, so ignore the MAF comment.

Nodge68 said:

Resetting adaptions isn't always a good move, as the the ECM has taken many hours of running to set them. The adaptions learn the engine characteristics as it wears, so clearing then puts the ECM to an "as new" setting, which won't suit an engine with many miles on it.

The MAF reading looks low to me. I'd expect to see much more than 6 g/s.
The timing between banks seems off too, I'd expect to see a couple of degrees variance at most.
The long term trims are ok, but the shirt terms seem at the higher end of acceptable.

Just my opinion of course.

Edit. The MAF readings are probably correct, I'm thinking of diesel MAF throughput, which is much higher than a petrol, so ignore the MAF comment.

Click to expand...

Thanks for the info. I must admit I was aware that resetting adaptations does more harm than good but I figured it could have had some bad data in there from the throttle body being gummed.

What’s the cause of short term trims being on the higher side usually? I assume that means it’s running rich.

I did also wonder about the timing. Although it didn’t seem horribly off.

HACKCHILD said:

Thanks for the info. I must admit I was aware that resetting adaptations does more harm than good but I figured it could have had some bad data in there from the throttle body being gummed.

What’s the cause of short term trims being on the higher side usually? I assume that means it’s running rich.

I did also wonder about the timing. Although it didn’t seem horribly off.

Click to expand...

Fuel trims are what the ECM has to adjust to maintain the mixture within the lambda ratio. So positive trims means the ECM is adding fuel to overcome a lean mixture. A lean mixture from an intake leak for example will be most obvious at idle, which is what the engine is normally doing while taking readings.
Try holding the engine at 2k to see if the short term trims get closer to zero, which is ideally where they should be. If they do drop towards zero, I'd be checking for intake leaks.

The timing could be the cam phasers, if this engine has them.