Mass Air Flow (MAF) issue, I’m stumped

[Scooterdog]

I just can’t figure this out, maybe someone here will have some insight…

My 05 GT went into limp mode, but got me home. Now it won’t idle well, sputters, and dies. Will run for less than a minute. Codes indicate MAF sensor problem.

1. I replaced the MAF sensor with a new one…same problem.
   
   
2. I cleaned and reinstalled the oem sensor…same problem.
   
   
3. If I unplug the MAF while the car is off, it will start up and run ok.
   
   
4. if I start the car with the MAF connected then unplug the MAF, the car will keep running. Reconnect the MAF, it will die.

So it must be related to the MAF sensor or connector or wiring or computer or ???

 

[Dallas281]

Have you replaced the throttle body or touched it at all? Check the voltage on it, it can be adjusted with the brass screw. It can cause no starts, rough idles ect. Although it sounds more like a tune issue, has the car been tuned? Could throw off the maf reading.. are you getting any codes? You could try unhooking the battery for a few mins to reset the computer and attempt an idle relearn

 

[JC SSP]

Check if the intake tube is mounted tight onto the TB.

 

[Scooterdog]

Thanks for the replies. The intake is nice and tight on the TB, and the TB hasn’t been touched. Everything is super clean, it’s a very low mileage car. Stock tune, battery unhook performed.

 

[Laga]

I had an intermittent short in the MAF wiring that only happened when the engine got hot, and the wires expanded from the heat. Had symptoms just like yours. Since moving things around changes your problem, check that the wiring is sound.

 

[Sammy70]

1. I replaced the MAF sensor with a new one…same problem

OEM replacement or chinese special?

 

[JC SSP]

Good point. MAF sensor should always be original Ford Motorcraft.

 

[Scooterdog]

Update. The car is running well now, but I really don’t know what fixed it. I removed the decorative engine covers and the air intake tube to inspect for loose or damaged wires/hoses/connectors. Found everything in perfect condition so I put everything back. Fired up the car again and it seems to be idling smoothly and running fine!

 

[DieHarder]

Intermittent's are bitches to troubleshoot. What was the last thing you did before symptoms started? I usually find the majority of electrical issues I've experienced were related to something I touched (adds, moves, changes, installed something, worked on a subsystem; etc.).

From your description my guess is MAF wiring. Rather than hunt around aimlessly here's a link to detailed troubleshooting steps (Pinpoint tests) for the MAF. Should help you isolate the problem down to the most likely culprits. https://iihs.net/fsm/?d=16

If you still don't isolate it you'll have to wait for symptoms to change/reappear or you can take it in and let a tech have a go at chasing it down.

 

[Scooterdog]

By the way, I really appreciate the help, especially since I’m new here. Great group!

 

[RocketcarX]

Look for evidence of rodents in your wiring if the car spends a lot of time sitting

 

[Whpony96]

Check the wires where they enter right at the back of the plug that attaches to the MAF sensor. Look closely if you see green or exposed copper you dealing with a wiring short issue or a broken wire due to corrosion. Simply de-pin the wires one at a time and heat shrink tube the wire and then reinsert and go to the next wire. DO NOT REMOVE ALL OF THEM AT THE SAME TIME SO YOU DON'T CHANGE THE PIN ORDER!

 

[86GT351]

Did you ever scan it for codes? For the future, even if no Check Engine Light always scan to see if there are any underlying trouble codes.

 

[Andrey Sidorov]

When you disconnect maf before car runs or even during - the ecm goes to fail safe mode right away (limp)- it will disregard the readings of your sensors and will run on preprogrammed settings - so it makes sense it will stay running, but it doesn't prove its your maf
So i ate a dog on this one (figure of speech) When i bought the car 4 years or so ago the car was always in limp mode due to IAT check code which is the part of the MAF, the issue ended up being the maf sensor wiring. I found the break, fixed it and half a year later it randomly started to do the same crap and Iat were always showing the highest possible temp which i think was 124F, car wasnt limping anymore, but you can imagine ran like crap since the reading was so wrong- ended up just cutting half of the harness off and soldering the maf extension cable from sct kit i think, that fixed the issue. You have to check the codes and what they relate too, it might be not even maf.

 

[Scooterdog]

ANOTHER update….

I started the car today and it went right into Failsafe Mode. Ugh! It threw 8 codes! Throttle/Pedal Sensor, Throttle Actuator Control, Mass Airflow Sensor, etc.

I started it again and it sounded ok, so I moved it around the driveway (not willing to trust it on the road). I wrote down all the codes, then cleared them.

AFTER clearing the codes, I scanned for codes again, and sure enough…2 codes. P0221 and P2106.

P0221 Throttle/Pedal Position Sensor/Switch B Circuit Range/Performance

P2106 Throttle Actuator Control System - Forced Limited Power

So, after all this, it appears to be a Throttle Body (TPS) issue. Guess I’ll replace it and see what happens…

 

[BCICAN]

The MAF wire harness was the issue for me . I found it myself after a “performance” shop replaced something that didn’t need to be replaced .They were idiots so I went and got my car back and did it myself . For mine it was the plug on the MAF harness that connects to the large 14290 harness . It had obviously been arcing and throwing things off there are 6 different wires in that connector so it was more than the MAF that it could cause issues for.
When I disconnected the plug it broke off inside so the shop obviously hadn’t even bothered to check it . I have also seen others post in forums talking about the same situations. In the picture I had pulled the CAI and flagged the plug on the 14290 that it melted in with a green twist wire. Hopefully this can help someone .

 

[Scooterdog]

Final update…

The new FPP throttle body has fixed everything. The car is now running as good, or better, than it ever has. Apparently the throttle position sensor has gone through a couple redesigns since 2005 because the original one was not reliable.

Lesson learned: one simple part can cause your car to throw several codes.