MAF Questions

[rdweninger]

hello all Soob gurus.   Suspect vehicle is 1985 EA82 FWD AT MPFI.     I know, I know... It is a rare Soob.  

  I bought the car a few years ago and put in new HG's.   Gave it to my daughter, and it ran for 2 years.

  Now, for some reason, it does not idle.   It will actually die if you don't give it any gas.   

  So, I do the following ...   1.  Remove and clean MAF (it is the flapper type).  2. Clean Throttle body.  3. Sand Disty cap and rotor with emery cloth.  4.  Check for water in oil (none)  and check for bubbles in coolant (none).   5.  Check for vacuum leaks (none).

  Now, I put it all back together and for some reason, the car runs GREAT.   Of course it is a bit cold blooded, but smooths out when warmed up.    Problem is, I now notice that I forgot to plug in the MAF plug wire (at the MAF).   When I plug it in, it runs like crap and will die if  idling-

  I actually put a new (used) MAF on the car 2 years ago.  Found one at BR Auto in Eugene.  

  Can someone give a few ideas of maybe what the problem is or maybe things to check to help with diagnosis.   I have limited experience with the fuel injection Soobs.   I always Weberize them.

  Also, how exactly do I read the codes from the ECU.   I have read some threads - do I need to plug or unplug anything first ... or just read them from the blinking lights?         I'll get to re-setting them later (after all is fixed).

  Thanks in advance for your help.    

[Fairtax4me]

Anytime you have a MAF sensor you need to check the air tube between the sensor and the throttle body for anywhere that air can get into the tube without flowing through the sensor. Any air getting in past the sensor is un-metered or "false" air , and is not accounted for in the AFR or load calculations. The result is a lean mixture, which often causes the engine to stall at idle.

Check for any cracks or splits, especially where the tube has bends or convolutes where it flexes. Make sure the clamps at both ends of the tube are tight. Check any hoses that attach to the tube for splits and make sure they are firmly attached at BOTH ends.

[rdweninger]

Yes, I checked the tube for cracks.   I actually removed the entire tube from MAF to throttle body... Cleaned with carb cleaner... re-attached and ensured everything was tight and additional lines were attached.

  When the plug is unplugged (as it is now), the ECS dash light is on.  However, no other dash lights are on.  Not sure if there is a check engine light on this model.   So, next, I will get under the dash to check to light flashes on the ECU for any codes.

  Anyone else have any wisdom to share on MAF and/or MPFI knowledge?