Hey folks, I've got an automatic 2000 S40 (1.9l Turbo Manufactured in Jan '00) that my fiance and I picked up a few months ago. The car had been sitting for approximately a year prior to purchase, so we knew we were in for some work. We've been slowly working on it to get the vehicle to its true potential.

To this point we have:
Cleaned the IAC,
Replaced plugs,
Replaced Fuel Pressure regulator,
Replaced rotors and pads,
Replaced front springs and strut mounts,
Replaced exhaust from after Cat to rear muffler,
Replaced rear O2 sensor,
Cleaned MAF sensor,
Replaced MAP sensor, (baro sensor was fine, but the MAP was splitting apart)
Oil Change.

Need to:
Replaced driver front wheel bearing (waiting to get bearing press)
Investigate further source of ABS and traction control light (likely a wheel speed sensor)
Strange behavior with engine Revving.

The engine revs up to about 2500/3000RPMs in park/neutral without touching the accelerator, then creeps back down to 800/900RPMs. This will happen in intervals of about 3-5 seconds. The issue has caused the CEL to illuminate with a code for an incompatible sensor value for the camshaft sensor (I can get the exact ODB code again soon) This behavior continues while in gear, but the effect is very much lessened.

Does anyone have any idea what may be wrong? Has anyone experienced a similar issue? Is there a guide for accessing/cleaning this sensor? My brother is a mechanic and pointed out that sitting for so long the sensor is likely clogged with old oil/sludge, but isn't 100% sure of the location.

Any help would be greatly appreciated, Thanks in advance.

 

That is strange behavior indeed. You need to pull that code and get the exact number. There is a camshaft position sensor on the exhaust cam. It should not have any dirt or oil where it lives. However, a leaking cam seal could let oil into the CPS housing.

There is also a CVVT solenoid to control oil flow to the CVVT hub on the exhaust cam. This one is subject to clogging from dirt in the oil. The new/redesigned gasket for the solenoid has a screen on the oil passage that can clog.

That said I'm not so sure a cam problem would cause your engine to rev without driver input. It will be interesting to find the answer.

 

Thanks for the input.

What are the chances you've got a diagram or pics of the location for the CVVT solenoid and the Camshaft position sensor locations? I'd like to check them at the very least if they're reasonably accessible.

Any other thoughts? Could it be related to the TPS reading strangely? It's doing this without seeing any modulation to the throttle.

 

Here is the camshaft position sensor housing. The sensor itself is mounted to the bottom right and sticks inside the housing. It's on the drivers side of the engine on the rear cam for the exhaust.


The CVVT solenoid is bolted to the head under the plastic engine beauty cover, passenger side. I don't have a picture of that one though. It's between the spark plug and timing belt and has an electrical connector so it's easy to find.

 

Thanks, I'll See about pulling and cleaning that CVVT solenoid tonight, hopefully that'll get the car inspection ready, getting to the camshaft position sensor looks to be a bit more work than I can do in the driveway, so lets hope that's not the problem, I don't have a clue when I can actually get in the garage this week.

 

pulled the CVVT, paper gasket underneath it is shot. it is also rather heavily discolored internally. Spraying it out w/ carb cleaner seemed to do it some good, the idle is still far from correct, but it's a bit more predictable now.

Going to look about getting a new gasket and another bottle of carb cleaner. Will probably change the oil next week as well. Any advice on oil additives for it? I have read a lot of good things about lucas, but nothing that totally sold me on it.

 

Before changing the oil next week, dump a pint of your favorite cleaning fluid in it today. My favorites include Marvel Mystery Oil or Seafoam or auto trans fluid (old school method). Run the car for a week then change the oil and filter. You do not need an additive with the new oil. Any of the 5W-30 full synthetics and a good filter work fine. (Expensive but they work)

 

Thanks for the tip, I'll look into getting something for between flushes. Since I've owned the car it's been full with Mobil 1 High Mileage full synthetic. I plan to continue that trend.

I might get the filter from Volvo directly this time, since I've gotta stop at the dealership to get the gasket anyway.

Completely unrelated issue in the car, ABS and Traction control lights are both on. I assume it's one of the ABS Sensors down at the wheel, but I've yet to get any codes regarding where the fault is. Drives fine, brakes work well. Any ideas?

 

I've even heard a quart of kerosene will clear out all that sludge. Drain a quart of oil and then add a quart of kerosene and let it idle for a while. Not sure about driving it with the kerosene but you can use it just before you do the oil change. I know it sounds odd but it breaks down the sludge.

 

After doing some reading on the kerosene option, it doesn't seem too appealing, since it thins out the oil. It definitely works, but the risk of letting it run to long and having it wear on my engine, which is already up over 150K doesn't seem too appealing at this time.

I'll probably buy some Seafoam or Marvel tonight, and as much as I know it's not necessary, I bought the car after it sat for a shade over a year, I'm sure it'd be nice to get a leave in style additive to really help clean the system out properly. Thanks for the help so far folks.

Again though, any thoughts on the ABS/Traction Control issue? Spoke with the parts guy at my local dealership, said that it's well more likely to be the ABS control unit and that he could give me the info for a local garage that rebuilds the ABS units and warranties their work for a year as opposed to ordering me a new one through Volvo. Knowing that the front springs were shattered when I bought it (I mean no less than 3 pieces/side... shattered), does anyone think that it may be more likely the sensor(s) since both ABS and Traction Control lights are on?

 

Okay, new gasket direct from volvo in place and... almost no change. Still starts at a high idle, then creeps down and surges back up to about 2500. Could this be related to the IAC, possibly a bad/dirty PCV? Throttle Position Sensor maybe?

The ODB code is cam position sensor -- signal incompatible. I'm really scratching my head on this one.

We cleaned the IAC after the car stalled in my fiance's father's driveway, but now this wacky idle seems to be a whole different beast. There's no vacuum leaks that we can find (we used map gas). Any ideas here?

 

From what I've read, if the code is for a bad CVVT solenoid then cleaning usually won't fix it. Replacement is the only option then. However, I've never read where the car had a strange revving issue to go with the code.

I would try this. Erase the code and disconnect the CVVT solenoid electrical connector to see if it runs the same as before. If yes then the same trouble code should reappear. In this case I'd consider buying a new CVVT solenoid. You could also try a Volvo junkyard to find a used one.

If something else happens like you now get 2 codes then I'd again erase the stored codes, disconnect the cam position sensor, and reconnect the CVVT solenoid. Now run the car again to see if the original code reappears. This would tell me the Cam Position Sensor is the problem if it acts the same without the CPS connected. Just trace the wire bundle out of the CPS to where it connects to the cars electrical harness up under the plastic cover. It's right beside where the 2 O2 sensors connect. It's simple to squeeze the metal clip and pull the connector loose.

I'll be glad when you find the issue. If it can happen to you then it can happen to me.

 

Thanks for the info. I'll give that a shot next chance I get with the car. In the mean time, do you happen to have pictures of, or a reasonable verbal description of the placement for the PCV valve? I'd like to pull that and check it for integrity/cleanliness.

Thanks!

 

If only we had a PCV valve. We have a PCV system for lack of a better term. It's an overly complicated routing of hoses and a catch can. See that large black hose on the top of the head? It routes down between the intake runners to a large plastic catch can like thing on the front of the block. Another hose (actually a metal hard line) takes off the catch can and routes over to the side of the head right below where the cam position sensor is located. The hard line mates to a flexible line that bolts to the head with a banjo bolt. You have to remove the intake to access it.

 

Well that sounds excellent...

Any experience with them needing replacing/cleaning? I'd rather not remove the intake if I'm taking a legitimate shot in the dark here.

 

From what I've read when the PCV system gets clogged you hear a whistling sound from the dipstick as the crankcase pressure is relieved there instead of being recirculated and burned.

Just a wild shot in the dark here. How is your main electrical ground? I've an old Fiero that will rev strangely due to the voltage jumping around when the main electrical ground is corroded. I had to replace the ground and then reprogram the ECM for a wider voltage swing versus the injector pulse width. (I can tune old chevy ECM's) I would try placing a volt meter on the battery to make sure you are getting ~14.4 volts when the engine is running. Can't hurt and it's a free test.

 

I'll look at the quality of the grounds today/tomorrow and buy a decent multimeter if I can. I don't think we've checked the battery yet. It's a walmart cheapy, looks pretty new though.

If that's what it is I'll be kicking myself for days, futsing with this car is getting a tiny bit exhausting.

 

I just replaced the PCV box on my 2003 S40 and you have to remove the intake manifold. This is rather easy given everything else I have done on the car. You only have to remove the top bolts that hold the intake manifold (same on the S70) the bottom ones just need to be loosen. Use a 1/4" drive - 10mm socket with a flexi joint and a long extension to loosen the bolts. Take off the dipstick and remove the metal bracket under the intake manifold (two bolts). Disconnect the cable that goes to the throttle and remove the various hoses. I had a slight advantage when I did this on my car the engine and transmission were already out of the car.

 

I have a problem that is similar to yours. The engine revs to about 2,500 RPMs at startup for about 10 seconds and then idles normally.
Did you resolve your idling issue, and did you fix the ABS trouble?
I am having similar problems, I hear that the speedo sensor could be the culprit,

 

Sadly, the car was not long for this world, I don't believe we had pinned down this problem. My wife was driving alone and some stop-leak in the radiator (previous owner) let loose and she was toast.

I would imagine checking the grounds and camshaft position sensor could be helpful.