The cap,rotor,and wires could very well be the problem also.If they haven't been replaced in a while could be the cause.The bad thing is so many things could cause problems like this.If the wire has a slit very well may be missfiring.

 

off the subject, I tried to reset the code by removing batt. cables, and the radio asked for code. I typed in the wrong code a couple times and it went to off mode. Now I know the code and it won'y=t let me type it in, how do i reset the radio?

 

You will have to leave the key in the accessory position for 2 to 3 hours.Most of the time it will not kill the battery.Make sure it is only in position 1 and only the radio comes on.When it switches from off to code you are ready to put the code in.

 

Ok so I replaced the plug wires, rotor cap, and rotor button. It worked fine for a while then started doing it again. The only other thing I noticed after going over it again, is where the throttle cable comes out of the firewall. There is a black plastic piece about 3" in diameter w. a plug connected to it. It appears as if it used to attach to the firewall, but has come loose exposing a spring behind it. It is only sitting about 1/8-1/4" off the firewall. Could this cause a problem. I am going to take it to volvo after this, but I fear it will cost a fortune b/c it sometimes goes for a whole day without doing it. I have spent more than $350 on parts that were not needed already. I know it has to be something simple b/c the car still runs great 90% of the time. If they can't find the problem, how much should I sell the car for?

 

See if that valve has any vaccum to it and if it is leaking.Im not sure what to tell you about the dealer and how much to sell it for if it isn't fixed.I keep trying to think of things it could be.

 

Took the car to a volvo tech who now has his own shop. The problem was two more vaccum leaks that where harder to find, the turbo pipe has a fitting on the plastic side that had an airleak, and the kick down switch was loose. Don't know exactly which one fixed it, but it's fixed. I am very happy, and will be increasing my price if I still decide to sell it.

 

Congrats on getting it fixed.Most of the time it is something pretty simple but just a pain in the butt to find.I can only do so much through the computer to help. Thanks for posting how you made out.[sm=roll.gif]

 

Tech, is the vacuum hose behind the power steering pump the one that runs along the injectors, and connects to the passenger side of the injector manifold? Is there another vacuum hose under the power steering pump that I can't see?

 

Do you mean the vent system hose that attaches to the end of the intake by the back of the power steering pump?

 

I have no idea what that hose is. The one I'm referring to is the one that connects to some kind of valve on the injector manifold, runs along the injectors, and to a plastic piece that's sits right on the air intake near the 'flap' (if that's what you call it). The plastic piece I'm referring to sitsright near the throttle body. So is there another hose under the intake manifold (somewhat near the PVC box) that I'm missing, or don't see?

 

Can you post a pic as an aid to your description?

 

Sounds like the fuel pressure regulator hose or the big black one that is for the vent system.

 

So what other hose am I looking for that's near/behind the power steering pump if it's not the fuel pressure regulator and vacuum hose?

 

Look on the end of the intake behind the power steering pump is there a hose there?

 

No, I don't see a hose. I looked with a mirror underneath, and I still don't see one on the end of the intake manifold.

 

OK then yours doesn't have one not all cars have it. Check all small hoses good.

 

Okay, so my car doesn't have the hose (850 GLT non-turbo). I checked all the other vacuum hoses, and they are all good. I gave the car a complete tune up (plugs wires, rotor, distributor), except for the fuel filter (of which I changed last year, but since then I had the fuel pump change...about 6 months ago), and I had the injectors taken out and cleaned professionally, and I cleaned the MAF with the non-residue cleaner. I changed the catalytic convertor, and both OS sensors because I was also getting a 422 code periodically.

I'm still getting the 172 code. Could it be the throttle position sensor (TPS), orthe coil, oreven as simple as the fuel filter again? If it is the coil, how do I check it? Or how do I check the TPS? HELP PLEASE!!!!!!!

 

If you have no vacuum leaks it might be the mass flow that is bad.

 

Tech,

Do you have any suggestions?

Thanks.

 

Opps. Sorry, I didn't see your comment. I'll try the MAF, and see. Thanks!!