It's a '93, 4.0 with 104K miles....When I went up a hill at highway speed the CEL came on...Cycled the key and it went off....Next hill same...didn't cycle the key this time and the light went off...back on, back off....It will run real sluggish at times, at other times it runs like a champ. Went to O'Reilly's and got there scanner...it says "cannot retrieve information from vehicle" On the way home (15 miles) ran great for first 5, went to crap, then ran great again. I've been under the hood listening for a vacuum leak or anything with no luck....I'm at a loss here...

 

weird. this pry doesnt help but just throwing it out there. If you need/want the light off disconnect negative on battery, turn lights on for like 5 seconds. then let it sit a few minutes, reconnect everything and it will be flashed.

 

Keep in mind your truck is an OBD1 vehicle. Orilleys probably thought it was OBD II

 

I used a OBD I unit...

 

Hmm I honestly don't know why. You obviously need to pull the code, but wonder why that scanner will not work.

 

codes came up137 no EGO.....which is O2 sensors.....put new ones on....still the same! On the paper it has 159 scribbled out, that MAF correct? Didn't notice that on the paper until just now....the other night I did clean the MAF and the ICM....I took it to the muffler shop today to check the converters, this morning it had the "bad" smell out the exhaust....coverters were ok....starting to think "electrical" I don't want to just throw money at it hoping!!!!!!!!

 

Did some more searching on this site....Figured the coil pack was the next guess. I did all the Ohm tests that the Hanes book said, couldn't get and reading between the wire harnes connector and where the plug wires connect (should be between 6500 and 11,500 ohms), got a new one and still couldn't get a reading. I changed it any way, couldn't hurt. CEL still came on, it did help the exceleration until the CEL came on, then it went to hell. Checked voltage on the MAF, within specs. Checked the TPS, was in spec....It's a 93 4.0 with the "X" VIN code for the motor, so it doesn't have a cam sensor (I don't have a clue how it know when to fire, would love someone to explain that to me)

I need some guesses here!!!!


Like I stated before it doesn't do it all the time...or at the same driving situations

 

My 94 was doing the same. It would run great then be sluggish. CEL was always on and when it would go out it would run even worse. I bought one of the cheap $30 code readers from autozone and it came back as a MAF sensor. That solved all my problems, runs great and fuel economy is back where it should be.