Help Please - 05 Legacy sputters out around 5 psi after MAF Cleaning???

**nvrgnadi** · #1: 03-12-2013, 10:44 PM

I recently did some work to my 05 LGT - It has basically been upgraded to an STI level stage 2 most of the mods were installed when I purchased the car and I'm reworking many of them as they were done in a shotty fashion to be nice about it...
anyhow

Uprgades are
-K&N cold air intake
-Perrin exhaust manifold
-Cobb downpipe
-Magnaflow exhaust
-STI intake manifold
-Top Mount STI intercooler
-Brembo Brakess
-Subaru indash tri-gauge pod
-Air/fuel ratio gauge (not sure of the brand, works well though)
-STI injectors
-HID headlight conversion
-Open source tune ith a VF40 stock turbo(modest tune but still upwards of 300hp still fun!

Here's the problem, I recently replaced the passenger side valve cover gasket, in the process i removed the cold-air intake pipe and decided to clean the MAF (w/ carb/brake cleaner which I now know is a bad thing to use) because the car has had some strange cold winter start idle issues lately so I figured it was worth a shot, oops.

Anyhow- I replaced the valve cover gasket, switched from standard oil to synthetic, peeked at the timeing belt, refilled the coolant and got everything back together no problem.

HERE'S THE PROBELM - When I started the car today 12 hrs after the repairs it was running very rich... basically when I would give any throttle the fuel/air meter would slam into the "rich" zone and the engine would sputter.

I shut the car off and when I restarted it it ran/idled just fine like it should, but I couldnt get any more than 5 lbs of boost witout it ging into the sputtering/flooding mode.

Could a MAF sensor be causing this problem?

HELP PlEASE!

**KCwagon** · #2: 03-13-2013, 10:39 AM

Bad news : Unfortunately, the answer is yes. The MAF sensor is reading AIR FLOW which, if damaged, will have a profound affect on your AFR readings. If you have everything else buttoned up correctly, then I would say that the MAF sensor was damaged.

Harsh chemicals like Brake cleaner on the MAF sensor is a bad idea. MAF sensors are very delicate and can de damaged easily. I am even hesitant about using "MAF sensor" cleaner on mine.

Good News : After you buy a new MAF sensor from Subaru, I suspect that you will not clean it with Brake cleaner again.

**nvrgnadi** · #3: 03-13-2013, 03:05 PM

I'm both relieved and upset at the same time although the damn thing was put in question numerous times as the cause of the rough idle so I hope it was the culprit!

Thanks for the help and I'll let you know if that's what it is for sure.

Later

**KCwagon** · #4: 03-13-2013, 04:15 PM

Yes, let us know. I have 148000 miles on mine and it seems OK. Hope a new one fixes the issue. Keep an eye on the AFR's in the mean time.

**Max Capacity** · #5: 03-13-2013, 04:34 PM

Feadbeans has a MAF sensor for $143.

**haycock** · #6: 03-13-2013, 08:51 PM

as i understand it, carb cleaner leaves a residue on the MAF sensor while MAF sensor cleaner leaves no residue. so maybe you can try cleaning it with MAF sensor cleaner before buying a new one. I'm not sure if it will wash off the residue or not but its worth a try.

**KCwagon** · #7: 03-13-2013, 08:55 PM

Quote:

Originally Posted by haycock

as i understand it, carb cleaner leaves a residue on the MAF sensor while MAF sensor cleaner leaves no residue. so maybe you can try cleaning it with MAF sensor cleaner before buying a new one. I'm not sure if it will wash off the residue or not but its worth a try.

That is a good idea.

**nvrgnadi** · #8: 03-19-2013, 10:59 PM

Well here's the update. . . and it's an interesting one.

Replaced the MAF sensor and the car was still running like crap so after some analysis we've come to discover that the fuel pump was producing little to no pressure so now i'm having a new fuel pump installed and then we'll see how it runs, there is possibility that the sensor may still have to be replaced but we wont know untill the pump is in. Talk about odd timing!

**cobb** · #9: 03-26-2013, 04:09 PM

Does it sputter and rpm drop if you just tap the throttle?

**nvrgnadi** · #**10:** 03-27-2013, 11:57 PM

We ridded the problem with the motor "falling on it's face"

So now that we've replaced the fuel pump I'm still showing signs of a rough idle. Usually when i just start vehicle cold in the morning.

It's obviously winter/spring right now but when it's freezing or below, the idle doesnt like to do it's job at all during any initial start up.

This morning it actually died on the 1st turnover.

I've read alot of threads on this issue and I've heard a few different culprits

-OCV
-Plugs
-IACV (not sure if this even exists on 05 and newer legacys)
-#1 most seen culprit is the injectors... more people say that once they replace the injectors they rid the problem, just like that.

I hate chasing invisible ghosts!!