so i have a 98 4.2 f150 w/ 5 speed. to my dismay, i got a check engine light the other day after the truck started acting funny. it wont hold and idle after i have been driving for a few blocks or so. i can start it in the driveway after a few hours and rev the crap out of it and it wont die (it comes close though). but when i come to a stop it will stall. it fires right back up, but i had to do some 2 footed driving to make it home. anyways i borrowed a friends scanner to see what the code was (the scanner is this one) and it wont connect to the truck. i hooked it up to my wifes car and it works on hers, but wont on the truck. i followed the instructions and it still wont display the little car icon (signifying it has a good power source from the vehicle) basically its playing like its not even hooked up. are there any tricks i am overlooking here or that i dont know of??? any ideas please!!!!

 

Sure. Check the fuse for the cig lighter - it also feeds the OBDII port.

 

For the engine problem it sounds like a EGR , may just need cleaning. The scanner may just be having a problem with connecting to your truck. I have 3 different scanners/code readers and sometimes my cheapest one reads were my expensive one has problems. Go to AutoZone and let them try to read it.

 

ok i got it to download. not exactly what mgdfan said, but it got me thinking about fuses and the slot that was supposed to have a 5a fuse for the dlc (slot 12) didnt have one, so i put one in and it worked like a champ. so thanks mgdfan


the code that comes out is p0102 any clues. according to the book that it came with its a generic code for "Mass or Volume Circuit Low Input" so i have no clue what that means. i assume it means bad maf, and that would make sense to me when i think about the symptoms. any ideas

 

Check this out: http://www.obd-codes.com/trouble_cod...-low-input.php

Try cleaning the MAF - use CRC MAF cleaner (don't use brake cleaner - too harsh, may leave a residue)- don't touch the actual sensor.

 

Could be the MAF or maybe a loose connection. Make sure the connection is tight, also look for corroding terminals on either the MAF or Harness connector. It might be as simple as going to the junkyard and get the same MAF off of another truck and replace the one you got. Would cost less than a new one to test that theory.

 

cool thanks guys, i will mess around with it a little more and see what happens.

 

Could also be the IACV, maybe it is dirty....Cleaner with throttle intake cleaner....