2001 NA P0300 rough idle ( CVVT SOLENOID BAD, NO CODES!!) Topic is solved

[George Dunham]

My 16 year old daughter bought her 1st car 3 weeks ago, a silver 2001 S60 NA automatic with 233,000. This is our families 4th Volvo covering 4 consecutive decades ( 71 1800, 89 240, 98 xc70), so I was pretty excited. I loved all of those previous cars.
Anyway- a week into driving the car, she asked me to drive it. She said something weird was happening with the suspension at freeway speed. Took her on a somewhat spirited drive up the freeway, and when we came to our stop, car was running very, very rough. No cel, but it died frequently.
Quick interweb search suggested sticking/dirty throttle body.
Did that and installed new gasket. Little to no improvement. Seemed like it was missing. Got it home, googled the problem. Suggested troubleshooting was to pull each coil with engine running and listen for click, click, click.
Cylinder 1 good, cylinder 2 no click, cyl 3-5 all had clicks.
Cool, we found the problem!
Order cheap spectra (or some similar sounding brand) coil from Rock Auto.
Install and there is a slight improvement.
Talk to a couple of mechanics. They always replace plugs when that happens.
Go to the local parts house. Only have Autolite 3923 in stock. Buy and install. There is a slight improvement that dissipates over time. Eventually running as poorly as initially.
Do some more focused research. Paraphrasing, but basically Autolites suck.
Shop for better plugs. very discouraging as there is no universal agreement as to which plug is good for this application. Plugs in the car were 7955. But multiple sources say those aren't right.
Went with Bosch 7401. Gaps seem crazy huge, but I've never seen a 4 electrode plug before. What do I know? Install them and get a slight improvement.
More research leads to buying all 5 new Bosch coils. Install and it is almost right! Idle is rough, lights dimming and brightening. Only throwing the cel every 3 or 4 starts and stops. Almost right, but not quite.
My daughter is tearing up, wife thinking about the same. What am I missing?
The only code that I have seen is p0300.
Any help will be appreciated. My daughter is so distraught and I am tired from scratching my head so much.



Last edited by [email protected]; Yesterday at 10:16 AM.

[850 LPT]

You may want to look into checking for vacuum leaks in the intake area. I'm thinking injector seals, vacuum lines, intake gasket, that sort of thing. Any leak in that area will cause rough idle.
I'm not so familiar with these P2 cars yet, but I just experienced a somewhat similar problem with my 850, and it had leaking/ missing injector seals and a leaky intake gasket. Replacing those parts cured the problem.

I hope this helps you out and you can get your daughter to smile again.

[chrism]

Forget all the platinum, iridium, multi-electrode, whatever the latest designer plugs that they try shoving down your throat. Try NGK BP6ES. They won't have them in stock. They'll tell you they're the wrong plugs. But they can get them. They just don't WANT to get them because they don't make enough money off of them. (about $2.00 each retail) What's to lose at this point - you're talking $10. Just make sure they're the correct reach compared to the depth of the threads in the head. 3/4" as I recall????

If that doesn't work, THEN move on to the more expensive possibilities.

[abscate]

The P0300 code is a generic misfire code. Is this a turbo car? You don't want the multi electrode plugs on a turbo, they are ok on a non turbo ( or Normally Aspirated, NA) car.

If you have all 5 cylinders firing it's time to look for vacuum hose problems..find the hose diagram under the hood and follow each and every one , removing each end, plugging and blowing in looking for leaks

Some folks think this is a good time to replace them since you have done the worst work removing them. They are correct.

Some really smart folks don't stop when they find a broken hose as the figure there may be more than one. That's why they are really smart.

[George Dunham]

Status update. Coils replaced with Bosch. Bosch 7955 (that's what was in the running car when we got it) plugs gapped at .028. Replaced the fuel injector O-rings. Replaced all vacuum lines but the oil trap related ones. Tested fuel system pressure at the fuel rail. Key on engine off pressure would bump up to about 57, then drop to 54 ish when key is turned off. Idle pressure around 58 until idle gets rough, then bounces rapidly (really shaky needle) between 52 and 59. Nice smooth 58ish when idle is smooth, ie not misfiring.
From my research, idle fuel pressure is high. This kind of leads me to think it is fuel pump or pressure regulator or pump control module.
But, there's oil on top of the head under the panel that conceals the coils. I have read that is an indicator that the pcv/oil trap is plugged. That system is part of the vacuum. Could this be it? Is there testing for that other than smooth running after replacement?
Thoughts?

[abscate]

Pop,off your oil filler cap and put a rubber glove on the cap. See if it blows up with crankcase pressure..that will tell you about your PCV

[George Dunham]

The glove sucked in.

[abscate]

Thats good. The generic misfire code can be a drag to figure out. I went through a phase with my 1999 when this one popped on occasion and I never really tracked it down. Keep an eye on the plugs to see if you can isolate a cylinder, take a compression test to see if you have a valve sticking, check intake manifold for a small leak (usually shows up on STFT though)

[George Dunham]

New update
Just brought the car home from the 3rd mechanic for diagnostics. They determined that it is the Variable Valve Timing Solenoid / Actuator. Interestingly enough, the first shop thought the same thing. That shop is owned by a good acquaintance of mine and offered to take a look at it without charge. Another Volvo mechanic thought it was a bogus diagnosis, that there would be associated fault codes if that were the case. Anyway, I removed the solenoid/ actuator, and tested the two terminals for continuity. Sure enough, it was a closed circuit, i.e. my little tester made a buzzing noise when I probed the two terminals. Buzzing noise went away when I removed the probes. Then I hooked up the solenoid the a battery. I have seen on you tube and what not people testing these. There is always a click sound, hopefully followed with the piston moving. Nothing. This part is bad, right?

[abscate]

You cannot test this solenoid this way. It is a frequency modulated solenoid, not an off/on switch.