XC70 lumpy idle/lack of power/bad fuel economy nightmare.

[FezMonki]

Could you point me to where to look in VIDA and what values I should be expecting? I'm fairly new to the thing, actually bought it specifically for this turd lol, the other Volvo's in my life only get as far as angrily blinking the led in the engine bay.

[- Pete -]

I retrieved some VVT solenoids today. I will clean them up, test them & contact you privately when I’m ready to send you one.

I’ll look in ViDA when I have some time. When my 2001 XC was misbehaving, I didn’t know how to get around in ViDA. I’m not much better now than I was then, but I will see what I can come up with.

[abscate]

You can’t really test them electrically. They have a test spec of something like 26 3.7 Ohms but I’ve had perfect functioning solenoids over a range of specs.

These solenoids are switched at a high rep rate of 250 Hz or more. They have to perform well over the frequency range

Corrected ohm spec per Pete

[- Pete -]

To test the solenoid/coil, though, you can check continuity; it should come in around 3.7 ohms, per ViDA.

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I test them with 12 volts simply to see if the plunger moves freely within the bore.
If the solenoid clicks but the plunger doesn’t move you can bet that it needs to come apart (if it’s the serviceable type) for cleaning.
If the solenoid doesn’t click & there is no movement of the plunger (and no viable continuity reading), the coil in the solenoid is dead.

All the VVT solenoids I got today (and my original 01 XC70) came in right around 3.8-4.0 ohms. I tested them cold, though it would be more accurate to test them hot.

FezMonki, is your original like the top right in this photo? If so, that is the non-serviceable type.

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I happened across this useful guide for disassembling the serviceable-type of VVT Solenoids.

[abscate]

Thanks Pete, corrected my post above. I had purge valves and boost valves On the brain.

[- Pete -]

I took some time after work to disassemble a couple of the junkyard VVT solenoids. Very simple construction & disassembly is exactly as depicted in the link I shared earlier.

One trait that I was particularly impressed by was how very tarnished and immobile the plunger was on both solenoids I disassembled! Both were intake solenoids out of 2 different engines, almost identical in overall condition (inside and out). It was a tedious chore to remove the plunger from its bore (using nylon and bamboo tools (the same tools I like to eat sushi/shish-kabobs with) to not marr any surfaces) on both solenoids.

Here is a photo of one disassembled, cleaned and ready for reassembly. For cleaning I used diesel followed by brake parts cleaner. You will want to be careful to not get brake parts cleaner on the rubber o-ring that seals the solenoid to the valve body. You’ll also want to avoid getting diesel or brake parts cleaner on/in the solenoid portion.

This was before removing the guts from the bore & thoroughly cleaning everything.

After cleaning everything I reassembled using engine oil and tested with 12 volts. It truly is amazing the difference it (cleaning) makes in the actuation! After seeing the before and after I’m pretty sure I’m going to take the solenoids off all my engines & repeat this process. I’m curious if any real world difference would be noticed.

Clean ————————————————-Dirty

Anyhow, FezMonki, I wanted to say that after giving it more thought, I think you should give the PPS solenoid a whirl. Post your ohm reading on it if you will also. I’ll still send you an OEM one if you’d like (disassembled, cleaned & reassembled or not). It’s up to you.

I honestly think that the first thing you need to nail down is timing & then let the engine purge itself of as much goop as possible (assuming it is goopy). The important thing here is you don’t want the goop to dislodge too quickly!

I meant to ask, has this idled this way ever since it was most recently purchased?

[abscate]

I recall at least one person failed with a new PPS SOLENOID , or cam reset valve as Volvo calls it.

[- Pete -]

It was kind of silly of me to recommend being careful with brake parts cleaner around the original o-ring that seals the solenoid to the valve body. The problem is, Volvo does not give any direction as to servicing these, nor do they have a spec for replacements (o-rings). No big deal, we’ll figure it out.

The o-ring channel on the solenoid measures a hair under ~15mm and the bore into which it will install measures ~18mm. Factory 16-18ish year old o-rings came in between 2.06-2.19mm cross-sectional width. For replacements, I opted for 15mm X 2mm HNBR o-ring for their heat tolerance & petroleum product resilience. I will be due for oil/filter change in around 400 miles on my 2001 XC70. I will install one of these “rebuilt” exhaust VVT solenoids (8670422, now superceded to 36002686) on my 2001 within 48 hours, run it the remainder of this oils life and check it periodically for leaks.

I have suggested to FCP that they start carrying replacement o-rings in the proper size & material for this exact application. The optimistic tone of the email I received in response was nice!

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[FezMonki]

Thank you for all the input Pete. I haven't had the misfortune of having the car in custody again to play with it, but it is now my belief that someone probably replaced cam seals due to leakage caused by the blocked PCV, and just bolted them back on without the tool or special procedure for the vvt gear.

As soon as I have it again (should be next week), I already got someone to borrow the tool from a Volvo dealership for me and we will re-seat the VVT pulley with the procedure I found. I'll also run some diagnostics on the solenoid and report back the results of all that.

In the meantime, just by having the new VVT solenoid on, disconnected, the car seems to be behaving alright and fuel economy seems to have improved. Possibly some lack of power, but it might just be the owner's butt dyno. Then again, that's what the VVT was for in the first place I guess.

Now the car started leaking coolant from the heater core onto the driver's carpet, of course, can't just have one issue at the time with this car.

Thank you again in the meantime for holding my hand.