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MAF sensor problem

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maf sensor
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42K views 43 replies 10 participants last post by  sergio87  
#1 ·
I did a spark plug change on my 02 WRX, and when I reassembled everything the car would start, rev up to 1.5k and then die. It took us forever to figure out that it was the MAF sensor, so we unplugged it and now it runs (I'm assuming it's running very rich to compensate). Of course it's throwing a couple CELs, which are...

1. Faulty MAF sensor/low input
2. Fulty IAT / high input.

I picked up some MAF cleaner, cleaned it with no luck. I just picked up a new MAF sensor and I'm getting the same codes.

Has any one else had this problem before? Any suggestions?
 
#7 ·
I guess I should have mentioned that I swapped all new plugs with the old ones before I figured out it was the MAF sensor, sorry.

With the old plugs, the car runs w/o the MAF connected, but starts and then dies with the old and the new MAF sensors connected. It's possible to keep the car running with the MAF sensors connected, but it's an extremely rough idle, and it's near impossible to keep it running. (It's to the point where you have to tap the gas to keep it running, which I feel is very bad for the motor)
 
#10 ·
I have to ask so sorry in advance but is the MAF oriented correctly (i.e. not installed backwards)? Are you absolutely certain that the correct coil pack connector is installed for each plug or anything else left unplugged? Is there any ground wires that got knocked about etc.? What were the sparkplug gaps?
 
#11 · (Edited)
The MAF sensor is installed in the correct position, all of the coil packs are in the correct place, the gaps are alright on the old plugs but could be better, but on the new plugs they are much more accurate, and more consistent than the old ones. The gaps on both the old and the new are between .28" and .31"

The only wire that I can think of that has been moved around a bit is the exhaust temp wire that has a braket connected to the back cylinder coil pack, on the passenger side. I didn't think of considering this wire an issue because the when the MAF is disconnected the car runs fine, but with a CEL.

(Edit)Also I made sure to place the wire back in the correct position after re-installing the coil pack.
 
#17 ·
I used the utmost care not to touch the IAT but I'm not sure if my friend did when he was handling it, which is one of the reasons I decided to go out and buy a new one. But the new one isn't working either. :(

I'm really hoping that the new one got messed up in the over night shipping, also the sales guy at the store I bought it from handled it pretty carelessly. :( I'm going to try and get the MAF. Off of my buddies sti and see if it works. *fingers crossed*

Sorry if the spelling was crap, I sent this on my phone.
 
#19 ·
IT'S FIXED!

I'm short on time right now, but I will post pics and the solution I found later today.

I feel that this solution and the problems presented here could be extreamly helpful to others. I learned a very expensive lesson today, and I want to do everything I can to help others learn it for free.
 
#21 ·
Alright, I'm very sorry for the extreme late reply, but I'm a full time student with a full time job living on my own so we know how that goes...

Anyways, this is the correct way to install the piping...
Image


It's quite obvious that the piping is supposed to fit this way. It fits perfectly and when installed backwards it's crooked.

I was reading online about MAF sensors and I came across a thread stating that the MAF needs at least 3 inches of straight piping in order to function properly. After thinking over this I noticed it did not indeed have 3 inches of piping.

So that's when I installed the piping like this...

Image


When it's installed this way, it's quite obvious that it's not supposed to be oriented like this. Whoever made the cold-air kit installed it like this to begin with and placed the MAF hole according to this orientation and this is what caused me so much trouble.

Long story short, make sure you have 3 inches of straight piping before taking your car to the dealership to get inspected...

Also on a side note the dealership just told me I needed a new MAF sensor and did not look at the piping at all.
 
#30 ·
I had the same problem. I did a spark plug change and when installed everything back together my car would start then die right away. I foud this thread and seen the pic that you posted of the Air Intake. The MAF sensor was exactly how it was in the first picture. So I rotated the intake pipe as you did in the second picture and my car started right away. The thing is the Air Intake looks funny that way. Can't you just flip the actual MAF sensor on the Intake Pipe?
 
#31 ·
On my piping it wont allow me to install the MAF in any other orientation.

I can't remember where I read this, perhaps another thread in these forums or somewhere else, that the MAF needs at least 2 or 3 inches of straight piping before it can get an accurate reading. I think the reason for this has something to do with the aerodynamics inside the pipe.