Camshaft position sensor

rebecca8 · Post by **rebecca8** » 16 Dec 2012, 14:55

I had another no start today. It seems the pattern might be something like this: I don't drive the car for a day or so. Go out to start it, maybe a 3 second delay, but starts. Go somewhere, turn the car off, and it either doesn't start, or does, but sputters, then dies. I am not able to start it again until maybe 30 minutes later. I took the car to 2 mechanics. The first shop kept insisting that there was nothing wrong with it. The 2nd shop replaced 3 vacuum lines to the intake manifold that were supposedly broken. They also cleaned out the throttle bore, and steam cleaned the injectors. This cost me $126, and they did the work before even discussing it with me first, which I clearly asked them to call first. They also said that if their repair didn't fix the problem that they're gonna want to try replacing the camshaft position sensor. Can someone tell me if my symptoms line up with this? I also was suspecting a bad fuel pressure regulator, but shouldn't these mechanics have checked that, and would that cause a no start anyway? I swear this forum is the only place I seem to get any reliable information.

rebecca8 · Post by **rebecca8** » 16 Dec 2012, 14:58

Oh, I also most likely have a failing PNP switch. Will this cause no starts, then start after a 30 minute wait? My car is a '94 Volvo 850 non-turbo. Thanks.

Post by **rspi** » 16 Dec 2012, 16:45

Yes PNP switches do cause random no starts.

Oh, the cam sensor will toss a code.

rebecca8 · Post by **rebecca8** » 16 Dec 2012, 17:42

Thank you. It does seem to be very random. It will start and drive fine for a week or two, then act up again. I had the car scanned about 2 months ago, and the only code that came up was for the MAF sensor, so I changed that. I guess I could have it scanned again, but do you know if the CEL light would also go on for a failing cam sensor?

Post by **Ozark Lee** » 16 Dec 2012, 18:05

The bad PNP is more likely to cause a no crank condition than a crank / no start condition. The crank position sensor can fail without tripping a CEL.

The CEL is set on the crank or camshaft position sensors when the engine starts but the two sensors don't agree with each other. The other CEL that can be set for a bad cam sensor is for an intermittent signal. A no signal condition from the cam position sensor doesn't always follow an intermittent signal, particularly if the connector isn't making good contact.

My Daughter had a flaky cam position sensor on her car but it would start every time. Its symptoms were that it would just up and die on the highway, usually in rush hour traffic.

You need to do some basic stuff the next (convenient) time it won't start like checking the fuel pressure and checking for spark. Since it is an intermittent problem your chances of having a shop find the problem are quite low.

All and all my gut tells me that you have a fuel pump relay that is failing.

...Lee

rebecca8 · Post by **rebecca8** » 17 Dec 2012, 11:05

Hi,
Thanks for your help. I actually just replaced the fuel pump relay. I guess since this has happened so many times now, I am able to conclude that the car does eventually start after about half an hour of waiting. Then, after it starts, it seems to be fine for a few days and even up to a week or 2. I also am able to predict if it's going to die out because of the rough idle and sputter, so when that happens, I don't get on the street, or try to hurry up and get out of the street. Another thing I've noticed most recently is a sulfur smell. My friend tried to start it, and got pretty aggressive, and floored the gas pedal after the engine turned over. That's when I smelled the sulfur. When he let up, it sputtered out and died. I've noticed this smell twice now. I read it might be due to a clogged catalytic converter, or something with the battery (I was told my battery is fine though). Earlier this year, the exhaust pipe cracked right after the cat. converter, and the cat. was sort of dangling. I was going to have them just weld a straight pipe, but then they said that for an extra $40, they'd replace the thing with a universal cat. However, I wonder if they really did do that because it has a strange color to it. Not rust, but almost like when metal gets burned, brownish/purple color. Perhaps, they didn't replace it, just welded it back on and it is clogged. Could this cause a random no start, sputter, stall problem? I'm not even sure if the O2 sensor was touched, or damaged. I would think an O2 sensor might just cause rough idle and poor gas mileage, but not a no start condition. Another thing I'm thinking is a clogged fuel filter. Could that cause random no start, and stalling? The clue I want to focus on is that it does eventually start after a wait. One more thing that has occured is that this has happened after putting gas in the car twice now. Don't know if that's significant. I wish I took auto shop in high school.

jgray850turbo · Post by **jgray850turbo** » 22 Dec 2012, 18:38

Hi Rebecca,

I think you have another thread going about this now, but I'll just chime in here.
I had VERY similar issues with my 95 850T. Especially the sputering or stalling when trying to start it warm. Wait a while and off she'd go. Also had the problem after fill ups, but I think it was mostly the same issue, ie. shut it off when warm and won't restart.
You can check some of my other posts about it, but it ended up being the fuel pump (or at least the hose connected to the pump).
Sounds like you don't mind doing your own work, it's not to hard. The hardest part is getting the large nut loose. They make a tool for it, but I was able to use a 'plier' type oil filter wrench to get mine off.
I chased codes, hoses, TB, icv, tune up, fuel filter, relays. It's been six months without those problems. (Just some others, lol, as we volvo owners love.)

Jeff

rebecca8 · Post by **rebecca8** » 18 Jan 2013, 18:22

I didn't see your answer until now. Thank you. It does sound like you experienced the same symptoms as I am now. Tomorrow, I will climb in the trunk and check that out too......to see if anything is obvious. I replaced a fuel pump in a Saab once, and it wasn't that difficult. In fact, I still have the fuel pump. I pulled it when I finally had the car towed due to other issues. This is probably a dumb question, but I wonder if it would fit in a Volvo. It's a Bosch. Probably not.

jacobharding · Post by **jacobharding** » 18 Jan 2013, 18:34

To get that nut loose use a large flat screwdriver and put the tip firmly against one of the tabs on the nut and then strike it with the palm of your hand or use a mallet or similar device. A few good strikes should get it loose enough to turn by hand.

Post by **JimBee** » 18 Jan 2013, 21:30

Tapping the large ring nut loose with a screwdriver and mallet does work and I've done it that way. My concern is shocking a sensitive electronic part in the pump since you have to knock it pretty hard to get it seal when replacing.
The best tool was mentioned above: it's an oil filter pliers with large concentric tongs with molded grippers on them. Works perfectly. I think most auto supply stores carry it. And in my opinion, it's also the best oil filter removal tool ever invented. Well worth having.