I've been having an ongoing engine surging issue that, after playing around with various vacuum hoses, seems to have settled down, albeit the car appears to be running lean. after going through emissions numbers are lower than two years ago. engine code 13 appears to be the constant issue.
CEL light came on this morning with a code 4, from pin 8. 4 Hot film mass air flow sensor. I reckon this means the air mass meter is faulty. is this correct?
the other little thing that happened was...there's this little semi-opaque tube that goes from some sensor on the left front of the engine, just behind the plastic front engine cover, to where the fuel pressure regulator vacuum hose connects. It was brittle and broke. What does this tube serve? is it possible that the lack of connection here would cause the CEL light, and engine code 4, to occur?
Thanks!