At my wits end - Engine System Service Required

[matthewrwright]

Bit of a back-story to this one.

The alternator freewheel pulley gave out on my 2009 2.4 185 D5 XC90 after a weekend away. A few moments of squeaking before the freewheel pulley self destructed taking a portion of the aux belt with it! Luckily the belt stayed largely on the shaft but the pulley took some damage with shredded bits flying off everywhere!

Luckily revs were low - I was literally reversing onto my drive at the time!

Immediately stopped the engine and went to inspect what had just happened.

Aux belt was shredded - instead of being 6 grooves wide, it was now 4/5 with the outer 2 being in pieces around the engine bay!

Ordered a new pulley and belt and set about replacing them - what a palava!

After a chat with the guy in Halfords when I realised I needed a T60 that I didn't own late on a Saturday night - he said "Check the cam belt too, sometimes the aux belt can cause the cam to jump a tooth"

So in for a penny I pulled the wheel, cranked the engine over with a spanner until the mysterious white tippex mark obviously left for me by the last person who did the cam belt lined up, and found the cam was 2 teeth out. Not being 100% trusting of the white mark I bought a cam locking set - locked the crank following the instructions in Vida and the cam was indeed 2 teeth out. Loosened the tensioner, slipped the belt off and re-fitted it lined up properly to the locking tool through the vacuum pump hole. Obviously cranked through twice with a spanner just for peace of mind!

So all the confidence in the world, fired the engine up and it sprang to life - a few words were uttered to the Swedish gods that obviously I'd missed mashing valves.

Enthusiasm and that warm glow of satisfaction lasted about 100 yards when the Engine System Service Required warning came up and the car lost all power! Barely limped it back round, parked up and went for dinner.

Got the laptop out and fired up Vida to find the following

ECM-135F Mass air flow (MAF) sensor - Signal too high
ECM-2AC0 Catalyst temperature sensor - Signal too high
ECM-6663 (+6664 +6665) Glow relay control - Faulty Signal
TCM-0A31 Control module communication Signal missing from Engine Control Module (ECM)
(plus the usual "they all do that" CCM-0040 air quality sensor error)

So... bear in mind the amount of things I've taken apart in diagnosing this, I have probably wiggled or jiggled every wire!!

Checked all my connectors to find nothing loose, though having shoved the two joints behind the exhaust heat shield back together extra hard I managed to get the ECM-2AC0 to go away (though it has been back since - so this may be a red herring)

When idling I'm seeing some crazy lambda figures... 3, spiking at 15 when revved gently! Reading live data in Vida I can see EGR valve 100% and EGR Valve Position sensor at 1%ish

Vida's suggestion for high MAF error was either swirl flaps (replaced about 2000 miles ago and plenum cleaned to within an inch of it's life) or EGR valve stuck shut - weird, but okay, there's a chance I've wiggled something I shouldn't I guess?

So EGR has been off, EGR cooler cleaned (was pretty clean already) but the EGR was absolutely awful! Slightly oily gunky but mainly carbon. Quick wipe with a petrol soaked rag and the carbon removed with a small brash wire brush.

EGR seals well when "closed" - tested by the technical method of blowing as hard as I could through the cooler, and breathes fine when opened.

Vida EGR values now move "naturally" as if the valve is able to move freely whereas before it was very jumpy and sticky.

Inlet system has been smoke tested to rule out the resonator box orange seals (they don't look amazing, but they aren't leaking) and other pipes- discovered a very small leak from the rod joining the actuator arm on the swirl flaps - removed the inlet again, removed swirl flaps and found a small bit of crud under the end of the last swirl support - cleaned it out, put it all back together, smoke test passed - as I was doing the whole inlet system I only did it to 1psi so as not to blow anything.


Have tested a known-good MAF sensor on the car too to rule out it actually being the MAF

The only thing I can see that I'm not happy with is I've metered the MAF.
Disconnected:
Pin1 - VBatt - roughly 13.2v running (battery was pretty dead from my faffing with Vida, leaving the boot open and the interior lights on etc.
Pin 2 - ground (but only when the ignition was on pos 2... otherwise floating)
Pin 3 - 5v (dead on!)
Pin 4 - 5v (also dead on)

The ground leaves me questioning if something isn't right, but I've read it earths via the ECU, so I'm wondering if there's a MOSFET or something in there?

Now - when connected to the MAF and probing the wires

Pin 1 - VBatt
Pin 2 - 0.3v (obviously resistance somewhere in the ground path, but not enough to be concerning
Pin 3 - jumping around a little - between 3.2 and 3.7v
Pin 4 - I _think_ 3.3v but wasn't moving at all

Pin 3 jumping has me concerned a little, but I couldn't work out which pin was which!

Removing the ECM connectors I can see decent continuity on all 4 MAF pins to pins on the ECM

All the Vida actuations seem to work ok - Turbo control makes the arm wiggle, Swirl Flaps makes the arm wiggle, EGR opens and shuts etc

My injector fuel trims are slightly outside of normal, with injector 3 being +2.6 mg/injection and injector 5 being about -2.7mg/injection - but they are original and the car has 190k miles... I'll let it off!

So... blood, sweat, tears - still not sorted! Even considered learning Swedish on duolingo so I could swear at it in a language it might understand!

Does any kind soul have any clue as to where I might look next?

[GrahamBrown1]

I take it the car was running fine before the cambelt jumped? Have you seen what happens to these when the cambelt slips? Where the followers sit in the head gets smashed. You may well have some internal damage that needs to be checked.

[Simmy]

cam . caps also break and it a known possible for the lobes to spin out of line on the shaft more internal inspection is needed to check the internals

[matthewrwright]

Thanks both! Yeah, running absolutely perfectly - had been towing the caravan the day before and it didn't even feel like the caravan was there!

Would you say the cam followers were sacrificial? They go before the valves bend?

Looks like I have a fun evening of pulling parts until I get to the followers! Luckily I already have the timing tools!

Cheers

Matthew

[GrahamBrown1]

Originally Posted by matthewrwright

Thanks both! Yeah, running absolutely perfectly - had been towing the caravan the day before and it didn't even feel like the caravan was there!

Would you say the cam followers were sacrificial? They go before the valves bend?

Looks like I have a fun evening of pulling parts until I get to the followers! Luckily I already have the timing tools!

Cheers

Matthew

In my experience the valves are fine but it’s the head that’s written off. If you find this is the case there is a company reconditioning the heads. Autotech cylinder heads if I remember correctly based down country. They will supply you with a recon head and cams. In my opinion this is the most economic repair.

If you YouTube salvage rebuilds they did a Volvo head job. They also toured this company’s premises to show you all that goes on. Well worth a watch.

[Simmy]

Originally Posted by matthewrwright

Thanks both! Yeah, running absolutely perfectly - had been towing the caravan the day before and it didn't even feel like the caravan was there!

Would you say the cam followers were sacrificial? They go before the valves bend?

Looks like I have a fun evening of pulling parts until I get to the followers! Luckily I already have the timing tools!

Cheers

Matthew

as you say your engine is still running any damage may be minimal if the cambelt shreds or snaps the damage is massive an costly there are some youtube vid on the kind of this kind of damage if you need to see whats involved this kind of event has sent lots of older d5s to the breakers yard.