My 94 ford ranger v6 4.0L was running rough. I replaced the iac valve and plugged the neg batt terminal back up and did a test run. It still run rough.it then threw a code to replace the purge container solenoid and I did. I had to replace my lower intake manifold gasket and when I did a test run it threw a code 157 . I already cleaned the maf twice during this whole process.when I first start the truck in the morning it idles high like it should and then after about 10 secs it starts to stumble and has some irregular idling . After it warms up a little it starts running like it should and the check engine light goes off. What am I not seeing or doing wrong that would cause this to happen. Please help me this is my only vehicle and i rely on it to an extreme .thank you

 

When you cleaned the MAF, did you use a plastic-safe cleaner or one that was specifically formulated for the MAF?

From what I've read, the symptoms you describe could either be the IAC or the MAF - since you said you replaced the IAC, I would look at the MAF.

 

Welcome to FTE.

P0157 = MAF sensor below minimim voltage.

If it came about After cleaning the MAF sensor, ^+1 on the non residual MAF sensor cleaning product. Did you remove & let it cool before cleaning, so as not to damage its sensor from thermal shock from the cold spray, or contaminate it when cleaning & were careful not to recontaminate it when installing, as we need to keep them squeeky clean & has been said & use a plastic safe non residual cleaning product, like CRC or Valvolene MAF sensor spray recipe product.

If it was dirty, you need to look up stream to find out why, as its only to see filtered air.
Typical contamination problems are, over oiled foam or cotton gauze type air filters, damaged or improperly installed air filter or seal, damaged air box, improperly buttoned up air box, loose or damaged air tube, modified air intake.

If all that checks out, then look to its electrical connector for corrosion, damaged pins spread sockets, wire, insulation, or low voltage to the MAF sensor or damaged signal return wire back to the computer.

If you have or can come by a scantool like an Actron CP9145 with cables that'll hook up to your OBD-1 under hood diagnostic connector & display live PID feeds to the computer, set it up to monitor the MAF sensor & post the numbers its reading.

Post All the trouble code Numbers you've had while working on this puppy, as they can offer up good trouble shooting clues.

More thoughts for consideration, keep us posted on your trouble shoot.

 

I appreciate everyones input on this headache of mine. I checked out all wires and plugs and anything and everything to do with the maf
but it all looks ok . I was sure to use a cleaner that was designed for the maf. I did wait until the truck was not started at all for 24 hrs before I did anything to it. The only other code it threw was for the purge container solenoid saying it wasn't working right in so many words. I replaced it.also during this whole process everytime I replaced something I kept the negative batt terminal unhooked for 10 mins and then drove it for at least 10 mins at a constant speed so the computer could reset itself.should I just go ahead and spend the 80 bucks and replace it or keep trying other troubleshooting deals?

 

You can disconnect the MAF sensor & probe its wire harness connector for B+ at KOEO, to make sure it has 12 volts to it. Then reconnect it & back probe the connector across the MAF Signal & Signal Return wires for 0.2-1.5 volts at idle, then raise the rpm to an rpm that typically gives you 60mph & the voltage should increase to about 2.0 volts.
If B+ is ok to the sensor, but if its sig rtn voltage doesn't go up with an increase in rpm, suspect the MAF sensor.

An option would be to swap sensors with a like friends vehicle, or maybe try one from a salvage yard donor.

More thoughts for consideration, let us know what you find.

 

Thank ya kindly sir I will try that it's more than what I had to go on in the first place for sure I'll keep y'all posted

 

Well I checked out everything and did my test on my maf connector and it all checked out good. I hooked it all up and did some just sitting there and also some turning off and letting cool down and restarting and etc.all day and everything is running like it should and no check engine light. Tomorrow may be a different story though . I'll keep y'all posted

 

If you haven't done the cold & warm idle relearn proceedure listed here, maybe do it after a battery disconnect to wipe the computers KAM, so it can also begin to build new fuel trim tables after the KAM wipe & idle relearn.
Ford Truck Enthusiasts Forums - View Single Post - high idle problem

 

K I'll try that tomorrow and repost thank you much sir