Turbo/induction troubleshooting 2006 XC70

saq · Post by **saq** » 08 Jun 2025, 13:27

The first O2 was surprisingly easy to get off, and power shot up, so it seems to be the exhaust. Guess I'll be (a) getting that off and cleaning it and (b) figuring out where the oil is going because evidently 1/2-2/3 of a quart per 1,000 miles is too much for the cat.
Or... I tend to drive the way that Packard recommended in the '20s - shift early and keep revs as low as possible. Does this style not mix well with recently designed cars?

wch2032 · Post by **wch2032** » 08 Jun 2025, 20:01

jonesg wrote: 03 Jun 2025, 05:52 reading your first post again, theres nothing to indicate any problems with the turbo but guessing.
I can't hear my turbo either but I know it gives boost by using a $12 ELM 327 on my phone.
I would want to read fuel pressure under load too.

I'm having similar concerns about my wagon's power. Do you know what the data field name is? when I use my code reader it says it's a calculated boost, and provides values in kPa or something, definitely not PSI, and it doesn't upgrade itself very frequently

how would fuel pressure under load reflect on turbo condition? Or are you making a general suggestion that low fuel pressure could be another reason for weak power?

saq · Post by **saq** » 10 Jun 2025, 07:33

wch2032 wrote: 08 Jun 2025, 20:01
jonesg wrote: 03 Jun 2025, 05:52 reading your first post again, theres nothing to indicate any problems with the turbo but guessing.
I can't hear my turbo either but I know it gives boost by using a $12 ELM 327 on my phone.
I would want to read fuel pressure under load too.
I'm having similar concerns about my wagon's power. Do you know what the data field name is? when I use my code reader it says it's a calculated boost, and provides values in kPa or something, definitely not PSI, and it doesn't upgrade itself very frequently

how would fuel pressure under load reflect on turbo condition? Or are you making a general suggestion that low fuel pressure could be another reason for weak power?

As I understand it low fuel pressure will frequently lead to harder starts as well as surging and misfires as you open the throttle because you get the air but not the fuel and, at least in the past, Jetronic couldn't compensate for it. ME7.whatever might, because when the fuel filter change slipped through the cracks on mine the first noticeable symptom was failure to start.
kPa because Volvo comes from a rational part of the world...you can convert if you must. Sadly I must because I don't work with pressure enough to understand what it means from the start, but I'm getting there.
Why not just attach a fuel pressure meter? That will read in realtime.

saq · Post by **saq** » 12 Jul 2025, 21:08

Final resolution - it was a clogged catalytic converter, but not coked up - it was a white ash. Evidently from burning oil and also a diesel thing sometimes. Front element in the cat was almost fully blocked. After trying to force it clean with hose pressure and soaking I saw in a diesel DPF post the suggestion to use dilute hydrochloric acid for about 4 hours and it worked well.
Next up is to pull apart the PCV system. Lots of oil in the intake, so if the turbo isn't failing the PCV is my other likely suspicion. Didn't think burning 1/2 a quart every 1000 miles was a big problem, but evidently with modern cars it is.

Post by **jonesg** » 12 Jul 2025, 23:50

I'd rather see oil on the floor than have it go thru the cat.

saq · Post by **saq** » 15 Nov 2025, 15:10

Clogged again... this time the cat is completely gone. Looks like inlet valve seals - get a huge cloud of smoke behind the car when I accelerate after using engine braking down longer hills now that the cat isn't disguising it anymore (if I coast in neutral not as much, so it seems to be responding to manifold vacuum not engine angle). Plus side - not the turbo. Downside - the simple stuff on this car takes so much longer than it should that I am not looking forward to resealing the valves.

Post by **jonesg** » 16 Nov 2025, 05:54

saq wrote: 15 Nov 2025, 15:10 Clogged again... this time the cat is completely gone. Looks like inlet valve seals - get a huge cloud of smoke behind the car when I accelerate after using engine braking down longer hills now that the cat isn't disguising it anymore (if I coast in neutral not as much, so it seems to be responding to manifold vacuum not engine angle). Plus side - not the turbo. Downside - the simple stuff on this car takes so much longer than it should that I am not looking forward to resealing the valves.

valve stem seals?
i'd look for a rebuilt head. and install an O2 spacer.