rough idle/check engine light blinking on 1997 Volvo 960

My 97 Volvo 960 started rough idling yesterday. The check engine light is always on, but with the new rough idle it started to blink on and off. I have an appointment with my Volvo mechanic. I've done some research and saw other problems similar. It could be Mass Air Flow Sensor (pricey repair) or bad connector of sensor wiring harness (low price repair), Fuel Pump Replacement (high price) or Fuel Filter (low price). I don't know anything about cars- is this on target or could it be something else? -beth

by in Charleston, SC on January 08, 2010
3 answers 2 comments
ANSWER by on January 08, 2010
When I saw your post the problem areas you mention were the ones that came to mind. Checking fuel pressure and deliver is easy to determine if the problem is fuel/fuel pump delivery related. Checking for vacuum leaks is important, a vacuum leak can easily cause your problems. Connecting a scan tool to the diagnostic socket under the dash illuminates the guess work or jumping to false conclusions. The scan tool checks data stored in the computer in your car an gives information as to what caused the Check Engine light to illuminate in the first case but also allows key sensor data to be read straight off the scan tool rather than doing more involved intrusive tests. What ever caused the Light to come is where diagnostic tests should start.
2 people like thisFlag inappropiateReply
ANSWER by on January 08, 2010
Beth, Some of these items you list do fail, but it's unlikely they are causing this problem. The blinking check engine light means that there is a cylinder that is not firing, or "misfiring". This is most often due to a leaking intake manifold gasket on this engine, but you could also have a bad ignition coil or spark plug. The first thing the shop will do is check the diagnostic trouble codes, make sure they note these codes on the repair order, and if you have any questions or concerns, post those codes here and I'll be able to give you some better info about what is happening. Good Luck, and try not to drive it too much if the light is blinking, this can damage the catalytic converter $$
2 people like thisFlag inappropiate
COMMENT by on January 10, 2010
@some guy, great additional info, I should've stated that and didn't, great advice!
ANSWER by on January 10, 2010
please be aware that driving a car with a flashing ck eng lt (active misfire) can and will cause catalyst damage if driven too far or too hot. if your mechanic is far away, consider towing it. cats are costly.
2 people like thisFlag inappropiate
COMMENT by on October 13, 2010
i think cost depends on where you buy the part. i bought a cat and exhaust manifold for 180 at 1aauto.com. the cost comes with installation, either do it yourself or find someone who will do it for low cost.