Any idea why my car could be running rich all of the sudden? I even haven't been messing around with it under the hood.

oil cap not on tight?

alignment of the planets?

CHT is going bad
FPR vacuum hose is off

lean backfire when cold and now a sticking air flow meter flap!

It's the hose that hooks into the air tube just behind the flapper box. It's come a little lose, and you're losing vacuum. I seal mine with teflon and a hose clamp. If you pull the hose out, your car will die immediately. I don't know how well getting rid of the hose and plugging the hole would work. It's only function is for the cold idle enrich valve.

A loose oil filler cap will cause this? I bet that's it then, my o-ring disintegrated not too long ago.....

Anybody know off the top of their head what size the o-ring is?

Thanks all!!

You have it backwards. If the hose comes off or the oil filler cap seals are bad, the car will run LEAN, not rich. You may have what the good Dr. says, or it could be the CHT wire on the RH cylinder head. If it is broken or disconnected, the system goes full rich thinking it is -50 degrees.


Check the AFM first. It is the most likely culprit.

If the CHT is disconected or "open" the car won't run.

Not totally true. If it is disconnected or open, it will be so rich that it probably won't run, unless it is really cold outside. If you remove the oil filler cap, you create enough false air to get it to run, but badly.