I'm clueless... Your turn!

[Silver Bullet]

Ok... I had a rough running issue recently with my 93' 3.2L ATX that was solved by throwing on a new set of Motorcraft spark plug wires + Plugs. It ran awesome for a week, and then a few days ago it started doing the rough running/misfiring again but worse. It starts up perfectly cold, idles fine & steady right where the tach should be, and even runs perfect for about 3-4 minutes until the engine warms up. Then it starts bogging down every time I try and downshift "Almost always a little over 2000RPM and above." Under 2000RPM it sounds and runs normal as long as I don't depress the pedal to downshift and accelerate. It also makes a popping sound during take off & downshift once in a while from under the hood like it's misfiring, and the tranny jumps around trying to determine which gear it should hit. At first I suspected maybe the new plugs were faulty, and brought the car back to the shop that installed them. The owner told me that it was oil in the plug wells that was affecting my spark, therefore causing the rough running/misfire. He said I needed a new valve gasket set installed. I drove it home and then back and forth to work for two days, and then decided to see just how bad the oil was leaking... To my amazement the wells were 100% DRY!

I ran my codes and got (157) + (158)... MAF circuit too LOW & also too HIGH.

Can my MAF malfunctioning cause my car to have the problems described?

 

[DHMag]

Yes. clean MAF with STP Throttle Body and Mass Airflow cleaner, reset codes, and try again.

another option is the wrong heat range on the spark plugs. what brand and P/N of plugs did you install ?

 

[Silver Bullet]

Hmmm... I know the plugs are MOTORCRAFT from looking at them, but I have no clue what the serial numbers were because a mechanic threw them in.

I cleaned the MAF filaments with brake cleaner this morning & it made a slight improvement where I can downshift once or twice during a cruise without the bogging down instead of not at all like before.

 

[SuperchargedSHOguy]

You should only use electronic cleaner as DHMag pointed out. Carb/brake cleaner can ruin your MAF's electronics.

 

[DHMag]

Motorcraft 42Fs are not the same heat range as 32FM. find out the P/N of the plugs.

 

[Rockledge]

Yes. clean MAF with STP Throttle Body and Mass Airflow cleaner, reset codes, and try again.

Good advice. If cleaning it doesn't help and the same 157/158 codes persist, then it's either a problem in the MAF circuit or the sensor itself is bad.

 

[DHMag]

while youre cleaning the MAF with the STP product, remove and clean the IAB.

if the codes go away but the problem persists, your gremlin is mechanical. my first choice would be the plugs. also, if a shop installed the plugs and wires, did they install the wires correctly ? the Chiltons manual is wrong.

 

[sdpatt]

It sounds as if the engine could be running lean. It would be okay during the rich warm-up period, but once in the closed loop mode, the engine control system is not able to maintain the mixture in the proper range. I am surprised that you are not getting any O2 sensor codes along with this situation. With the MAF codes your are receiving, you have a good place to start.

 

[Silver Bullet]

Thanks guys for the advice and help.

The part number for the spark plugs that were installed I found out was AGSP32PP. I got some electrical contact cleaner from my work today, and gave the MAF filaments a good shot of it, along with the sensor connectors. I am about to reset my codes, and go for a test drive now. I'll let you know if the problem gets better or even disappears (Fingers Crossed).