D5 intermittent chug

[monkeh]

So,
My d5 XC70 has had a random intermittent chug at idle.
Sometimes idles beautifully, more often the chug is when warm.
Putting it down to spotting the swirl flap linkage hanging and buying 169k worth of free egr buildup, I anticipated it could've been related. No boost leak from the flap arm, replaced arm as old one was worn.
Egr was promptly cleaned, A good inch of black shmoo removed.
Still chugs.
Egr has been mapped out along with a remap. Still chugs...

Vida reports the flap motor works, also injector leak off are all minimal values and similar.

I'd thought a spirited drive would help fix it. Nope... Driving it doesn't produce any flat spots and she drives perfect.

Do I go down the route of inlet manifold removal?

Long term plan was to replace the flaps and deep clean the manifold. Along with physically blanking off the egr to eliminate it, just in case it may be letting in spurious fumes.

Any other things worth having a look at?
My experiences with the d5 are limited, dive me a d24tic or a 6bt Cummins any day!

[monkeh]

Update:- Flaps are out, Appears to be a lot of play between the linkage and flap assemblies. I have also extracted the EGR cooler for cleaning and eventual blanking.

Inlet manifold is crudded up but not as bad as EGR. EGR seemed to be the bottleneck in the system. Ports had a good few millimeters of goo around it. They've now been scraped clean.

I will steam clean the inlet manifold- Its currently sitting in a nice bath of petrol to soften up the gunk for a few days. (I know its plastic) but quick shots won't hurt.

Next port of call would be injectors...
The saga continues.

[Oak]

Originally Posted by monkeh

Update:- Flaps are out, Appears to be a lot of play between the linkage and flap assemblies. I have also extracted the EGR cooler for cleaning and eventual blanking.

Inlet manifold is crudded up but not as bad as EGR. EGR seemed to be the bottleneck in the system. Ports had a good few millimeters of goo around it. They've now been scraped clean.

I will steam clean the inlet manifold- Its currently sitting in a nice bath of petrol to soften up the gunk for a few days. (I know its plastic) but quick shots won't hurt.

Next port of call would be injectors...
The saga continues.

When you say chug - you'd not describe it as a "chuff" would you? I had a few chuffing injectors on my D5 as a result of the copper washers needing replacing on the injectors. I managed though to tap the injectors lightly with a rubber mallet and tighten up the mounts. It's been like that nearly two years now so seems solved?

[monkeh]

Hi Oak,
There's no chuff. I've dealt with injector chuff in the past. All 5 were seated lovely with no leak.
I describe it as chug, as when left to idle, the engine seems to rhythmically stumble to a slightly lower rev, almost like a very fast hunt, every half a second between these cycles. Revving the engine doesn't show any sluggishness, it doesn't bog, nor create any excess smoke. But it's intermittent!
With the amount of accumulated goo that is in the inlet, inlet ports plus condition of flaps, I'm hoping its that, but the manifold is still soaking in its solvent bath. It'll be steam/karcher time today.

I've had similar on Mrs Monkeh's yaris but that was caused by a blocked egr. (Simple vac operation)

[passenger]

Is the same when engine cold and warm is?

If you block EGR, how you will pass readings on teh.inspection? I was thinking the same, to close EGR, but I'm not sure about inspection tho