I have a 1998 Volvo S70 T5. The vehicle only starts up when I disconnect the mass air flow meter, but stalls when I reconnect it. I have tried replacing the mass air flow sensor and the problem persists. The check engine light is on constantly and the service light is on for the first few minutes after starting. When the vehicle is on, it runs rough and when it is driven there is a significant loss of power. This problem started when I was driving from NC to NY and there was a huge downpore of rain. If anyone has any ideas for diagnosing this problem, I would really appreciate it. Thanks

 

When you replaced the mass flow sensor did you clear the codes?

 

Update: Today I replaced the air pump and it looks like that was the problem. The check engine light is off and the car isn't stalling with the mass air flow sensor connected. I was also wondering if anyone knew why there is smoke coming from my dipstick? Thanks again!

 

I cannot see how the air pump would keep it from running. Maybe the computer relearned there was a new massflow. For the smoke the vent system is plugged somewhere.

 

Does anyone have a diagrahm of the vent system or any ideas on how to check where it might be plugged up?

 

Check FCPgroton.com for the parts list Check all the small hoses for clogs. If all that is good then the vent box is clogged.