Okay, here it goes.
I took the advice from my previous post about the timing belt. My husband changed the belt and it is still doing the same thing. It WON'T stay running and won't go over 500 rpm. It idles SO rough it isn't even funny, if you try to give it fuel it dies. So we checked to see if the fuel pump was bad, nope fuel dumps out of the line. It has good compression, between 185 and 200. Then we checked the catalytic converter, not plugged. Changed the fuel filter. Checked the spark plugs, #1 was dirty, the next 2 were not as bad and the last one closest to the firewall came out with a BIG fight. It also broke off when my husband was trying to unscrew it, we got it out and it looked as if it might have been there a long time. Like it had made itself part of the car. LOL
But my question is: Do you folks think that the spark plugs could be the problem? It won't stay running is it is next to impossible to get it to a shop for diagnostics. All the Volvo shops are 20+ miles from my house so towing would be expensive.
Any help/ suggestions are appreciated!
Thanks!!

Hi Christee.

Have you or your husband checked the fuel pressure regulator for proper function? That's not easy to verify pressure, but you CAN verify if it's getting too much fuel by pulling the vacuum line on the end of the regulator and seeing if it's got raw fuel in the vacuum hose.

Spark plugs COULD cause it, but it would be better now if that was the case. And they don't die suddenly, at least in a whole set of four. Usually one goes bad first, or they all gradually degrade.

Have you checked the diagnostic link under the hood for trouble codes? It might help trace the problem.

It ALMOST sounds like a bad mass airflow sensor. Although the later ones don't die much. Sometimes if you UNPLUG the MAF sensor (only with the car OFF) and try to start it, it will run better. If that's the case, you've diagnosed the problem, and you can actually drive like that, although I wouldn't recommend doing it for a long distance as it doesn't run THAT well.

Also, is the check engine light on? Is it functional at all (i.e. not burned out)?

Check the distributor cap and rotor for the basic cleanliness.

Verify that there are NO intake air leaks between the mass airflow sensor and the intake manifold. That means, no loose vacuum lines, no cracked intake hose, no leaks of any kind. A BIG one will cause the engine to not run at all, like you've said. Since you've verified no exhaust restrictions and good fuel pump, it seems as if the problem might be elsewhere.

So, to recap some likely causes:

1. Mass Air Flow Sensor
2. Fuel Pressure Regulator
3. Intake air leaks
4. Distributor cap problem (arcing, carbon tracks, busted contact for rotor, etc)

Let us know what the results are.

--
Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240

Christee,

Have you checked the Air Mass Meter? If not ... let the car sit for a few minutes with the key off. The disconnect the wiring plug to the AMM. Then try and start the car. It should go into the limp home mode. Not much power but it should be able to limp home or better yet to the repair shop if it's a bad AMM. Don't plug the meter harness back in until turning the key off and letting it sit for a minute or two. Replacing the Air Mass Meter is easy but the piece is expensive. Also check the out put of the O2 sensor with a meter to see if it's alive and well. Do look for vacuum line leaks. Also check your coil wires to make sure they are clean and making good contact. There are some Fuel Injection grounds that connect to the intake manifold just under the fuel rail bolts. Clean them of all signs of corrosion ... put a little die-electric grease on them if you have it and make sure they are snugged down and making a good connection. Those grounds can cause a lot of problems with just a little bit of looseness or corrosion. Hope you can sort this out and get your brick back on the road again. Good Luck.

A long shot, but it might work:

Several years ago I had an '87 740 that would not start if the engine was warm -the starter would work and the engine would crank but no starting - timing belt, fuel pump, O sensor, air mass meter - we checked it all. I eventually broke down (literally and figuretively) and took it to a very experienced Volvo mechanic here in Houston. They had my car for a week and couldn't figure out what the problem was. Finally, just on a hunch he started replacing my relays one-by-one down below the radio. Guess what? The culprit was a $20 radio spark supression unit - somehow it screwed up the signal to the electronic ignition control. Why, who knows!

VOLVO's - gotta love 'em!

Try that out if you have come to the end of your rope (literally or figuretively), it just might work.

Sam
'93 940T 145K

Have you checked your oxygen sensor? These can do a real job on you too.
dick

Christee

I'm impressed that you work with your husband on the car. Whenever I suggest to my wife that maybe we should work on the car for fun, I always get a look back that says "year right". I love working on my cars, but I wish my wife would once in a while join me in my fun.

Anyway, to your problem. Since you changed the timing belt, and if done correctly there would not be any problems with the valve timing. Also, I assume that this problem with the car running very rough came over-night, and not gradually. I don't think the sparkplugs would cause the car to run that rough. However, I would replace them anyway. Sounded like one of them broke when you took it out. Now, I didn't read your ealier post, so I don't know what other people have suggested or what you already have done to the car, but here are some of the things I would do to the car if I had the same problem:

* New spark plugs
* Measure the resistance for each spark plug wire and inspect wires for cracks. Don't forget the wire between distributor and the coil. Replace it the wire doesn't pass the test.
* Check distributor coil and cap. Replace if near or over recommended mileage, or if they are cracked, burned or otherwise look bad.
* Inspect and measure resistance on the coil.

If the car still runs rough after you checked the above, I would check the following:

* Make sure you don't have a vacuum leak anywhere. Spraying throttle body cleaner around all over the intake side of the engine from the air flow/mass meater all the way to where the air would enter the engine (vacuum hoses, around gaskets of throttle body and the gaskets between intake and the and don't forget around around fuel injectors to see if injector seals leak). If you hit any leak, the engine rpm will increase.
* Check that the temperature sensor that controls a cold start works. It is located under the intake plenum. Note there are two temperature sensors underneight there and one controls the water temp guage in the dash, the other one goes to the computer. If it is broken it could think the car is fully warmed up, when it is not and not supply enough fuel to a cold engine. Basically the engine would not go into the cold-engine mode. I would just measure the resistance when it is in the car and not worry too much about taking it out and heat it up, as it is the cold start you seem to have issues with.


All you need is an Ohm meter and some simple tools to do the above. It seems you husband is quite handy since he already has replaced the timing belt. The above is much easier to do than the timing belt. In any case these are things you should do regularly anyway. Let me know if you have any questions and the results once you have done the above.