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Red Emblem
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490 Posts
Discussion Starter #1
So, I think I fried my MAF somehow, but before I jump the gun I want a second (or as many as I can get) opinion. Here is the situation:

The car runs like crap. It is running rich as hell and it idles horribly. You can’t rev the engine past 4000ish rpms. I checked for codes and I’m getting 12 back: MAF. Did all the diagnostics run downs:

~Checked power supply (Had ignition to “On” engine off, checked voltage between terminal b and ground), it came up correct around 12ish volts.

~Checked ground circuit (Removed ECU harness and check for continuity between terminals c and 48 {OBDI to OBDII harness adapter which leads to 17}), continuity existed.

~Checked input signal circuit (Removed ECU harness and check for continuity between terminals d and 47 {OBDI to OBDII harness adapter which leads to 16}), continuity existed.

All the wires checked out so I went on to check the MAF it’s self:

~Checked voltage between terminal d and ground and I got back between 0.04 and 0.07 volts. I assumed that would be the huge issue.

I took apart the MAF and cleaned it to see if it would help, looked if the sensor looked damaged (which it looked fine). But, to no avail it still ran like crap, still gave me back code 12, and still gave the stupidly low voltage. I unplugged the MAF while the engine was running and it dropped to a normal idle, stopped burning a crap ton of gas, and I believe the ECU fell into safe mode seeing how I cant rev past 3500 rpms now.

So, all that being said does everyone agree that the MAF is blown?

Thanks everyone.

The setup: 98’ B14 with Gti-R w/ stock injectors and sensors, FMIC, Gti-R Mine’s tuned ECU, B14 harness, B14 to B13 ECU adapter, Gti-R MAF… believed to be shot.

Also to note, anyone happen to have a Gti-R MAF for sale? A working one?
 

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Big Cheddar fan club
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1,466 Posts
Just a thought... try re-grounding the maf.... may or may not work.
 

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CAR SLÜT
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1,622 Posts
U13/GTiR MAF is a common failure item. I would say that it is the problem and the circuitry in the MAF is what dies, not the element itself.
 

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love the Florida sun!!
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1,906 Posts
Have you check for possible boost leaks yet? Exact same thing happened to me, i found a boost leak at my hot side hose where the turbo outlet meets the intercooler...

does it stutter and blow black smoke when accelerating?

Whats your vaccum reading at idle? It should be between -20 to -17
 

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Red Emblem
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490 Posts
Discussion Starter #6
Thanks for the regrounding advice and the link, but no dice. I still get the same problems and the ECU is still throwing me code 12 (MAF) after the regrounding.

Yea, I figured that the internal workings itself must had died on me.

I haven't checked for boost leaks, but I will do so in the morning. Thank you for the advice. She normally ran around -18ish range. With the MAF unpluged she sits at about -12, which your right on it looking like there might be a leak but I dont know how the car would act without the MAF pluged up, so that might be normal. As for when the MAF was hooked up she juggled between -5 and 0 as she attempted to idle.

Anyone else?
 

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Big Cheddar fan club
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1,466 Posts
sorry no dice... I like to go simple first.
 

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love the Florida sun!!
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1,906 Posts
I haven't checked for boost leaks, but I will do so in the morning.
Anyone else?


I'm almost positive its a boost leak, when i had my boost leak my ECU was tripping a 1,2 code over and over until i found the boost leak and fixed it .

When you do look , be very thorough, loot at every single vacuum hose and boost hose , it may take you some time but be patient.

It took me 1.5 weeks of trial and error but i found it .....you'll know its fixed when you go to rev it up you'll prolly see a crap load of black smoke from the tail pipe....
 

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Red Emblem
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490 Posts
Discussion Starter #10
Update: So, I'm new to the whole checking for boost leaks things so let me know how wrong I did this. I made a "homemade" pressure tested as told elsewhere in the forum. Hooked it up to the turbo inlet, found first a small leak on the exhaust side of the turbo fixed it. Then found a small leak at the BOV, fixed that too. Now I never found out how exactly how it all is suppose to work but I always was slowly losing pressure. I would put about 10 psi in the system and that would last me about 1 minutes before it was back to zero. I assumed that gas would always be leaking through the engine, so I don’t put much mind to this. Was this a correct assumption?

Regardless, after fixing those two leaks I then went to see if it fixed how she ran. I tried her first with the MAF unplugged and in limp mode. She ran the same: steady idle at around 950 and wouldn’t rev above 3500. I now sat once again around -18ish on the boost gauge. So I figured that I did do the boost leak check correct and I did have a leak or two. I did notice that at initial start up she sat at about -12~-14 after the first rev she went to -18ish and held there.

So, for the test: I plugged in the MAF and it went back to being crap-tastic: running rich as hell, spiting and spurring, and having a very unsteady idle then almost dieing.

So, bad MAF?

Also, did I do the boost leak check right and is it normal to lose pressure over time?

Thanks everyone!
 

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Red Emblem
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490 Posts
Discussion Starter #11
Got a new MAF in and she works right-as-rain. Thanks everyone!
 
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