GuardianMagnuSS

I don't know if my MAF sensor is bad, I'm asking you guys what ya think and see if I can troubleshoot it.

So went to my mechanic after check engine popped on and off a couple times and scanned it, read codes P0171 and P0174 lean banks he might of got another code but he didn't show me it, or I forgot it.

He said it was most likely the MAF causing those readings but I know it could be a vacuum leak too. I don't have any loot right now to get it fixed not until next month or so.

My questions are 1. Will it hurt anything if I drive with a wonky MAF? 2. Does anyone suggest unplugging it and going into Speed Density? For the time being till I can replace it. 3. Is it my MAF, how can I troubleshoot it on my own without a scanner? 4. Do I even replace the MAF or go for a SD tune? I plan on getting wheels and tires soon then headers after that, so I wouldn't be getting a tune for a while though.

My friend might have a scanner I need to ask him, that's if it's really needed.

I've read a lot about this but just want the interaction and recommendations from any of you guys. 02 SS, car is all stock that I know of btw. Appreciate any responses, Thanks.

ss performance

iTrader: (17)

Tap the MAF with the handle of a screw driver. If the engine "stumbles" when you do this then MAF is bad.

Good luck.

demonspeed

iTrader: (7)

This.

I would also check all you vacuum, PCV, and AIR lines for cracks. A bad (clogged) AIR check valve might also throw those codes.

Lastly, you could also try cleaning your MAF with electronics or MAF cleaner.

lt1pwr1

iTrader: (1)

The easiest way is to swap with a known good one and watch your fuel trims. Other common thing is for the intake gaskets to go bad. With the engine cold, you can start it and spray some carb cleaner around the intake to see if the idle changes (vacuum leak).

GuardianMagnuSS

Thanks I just tried and it didn't do anything so good there I guess. While I had the hood up I did hear a whoosh noise just once and then nothing. I wasn't tapping on the MAF at the time as well.
Car is warm now, I'll wait for it to cool down and see. All I have is starter fluid is that ok to use?

LS6427

iTrader: (2)

Both banks lean at the same time......probably a vacuum leak, but 02 sensors have failed or started to fail around the same time too.

I ran my old 427ci for two straight years with my MAF unplugged, ran like a charm, perfect. Perfect starts, perfect idle, perfect everything. MAFs are not needed.

I dont think a bad or failing MAF can cause the engine to run lean......bad 02 sensor(s) do, or like you said, a vacuum leak.

Also, the MAF isn't even being used when the engine is up to operating temp, or past 122*F coolant temp. So doing any diagnosis when the engine is warmed up wont work with a MAF. The MAF is being used by the PCM when the engine is started up COLD.....and then the only other time it comes into play is when you go WOT.

-----is everything normal when you go WOT.....power, smooth, normal....? If so, the MAF is fine. Also, if it starts normal, idles and warms up normal, the MAF is fine.

You need to look at the 02 sensors with an OBDII scanner to see how they are switching while the engine is running. Not a code reader.....a scanner.

Like mentioned......swap the MAF with a known good one from a friends car, clear the codes and go for a drive. Who knows what these crazy PCMs will do......maybe it is the MAF.
But it could be other sensors as well....IAT/TPS causing issues and wigging the PCM out.

Or do what I do.....go buy a new one, put it on and see if it fixes it. If it does, keep it. If it doesn't wipe it down real good and return. Tell them you NEVER even installed it and they will refund your cash.

.

GuardianMagnuSS

I'm a complete newb so bare with me, I love cars but I am no mechanic. Lets just say Im aspiring, so I don't gotta pay for labor if I don't have to.

Are those all separate lines? I know the PCV and can follow that. Are there other spots to check?

I have some electronics cleaner so I'll give it a try when the rain and snow stops, damn New England weather!

Carguy8888

iTrader: (1)

Following too.

GuardianMagnuSS

Ok so if unplug it say the MAF is bad do I gotta do anything else or just unplug?

Ive run it with/without MAF plugged in a couple times, and I think I unglugged some fuses to clear the ?TRIMS?. Is that necessary?

Ahhhh yea my engine was warm when I did the ol' tap test. So now I don't know if its bad or not. Wont know now till it stops snowing.

Yea everything seems fine. WOT - GOOD, Power seems fine, runs smooth, normal idle.

This is only nice car Ive ever had so all seems good to me, but to someone trained they might notice something.

Only things Ive noticed a bit odd. A couple times trying to do some burnouts, it bogs some or slips. Also, this happens a lot, when cruising at about 40 MPH at I think 1300ish-1500ish RPMs it bogs if I give it some gas. If I really step on it I don't think it happens. Maybe Tranny slip? Separate problem?

I got a buddy who uses Tunercat for his LT1, I would need the connector and the file for LS1. Or I could get a handheld. Or HP tuners is what I really want.

Ill try the tap test again when I can, and see what happens. My friend uses a MAF so I could do the swap, or Ill try a new one last case scenario. Thanks

demonspeed

iTrader: (7)

Those big tubes coming off the exhaust manifolds -- those are for the AIR system. Just follow those to the black, round metal thing that a rubber hose attaches to -- that's the AIR check valve. From there you'll follow the rubber hose to a valve on the driver-side of the intake manifold toward the back (under the cowl). There you'll see some smaller vacuum lines (some of which go to the back of the intake manifold). Lastly, that rubber line that runs along the driver side fender and down under the headlight -- that goes to the AIR pump.

Anyway, since you know the PCV system, pay close attention to the shorter hose that connects the PCV valve to the manifold as these simply dry out and crack over time (and likely cause most of these issues!).

GuardianMagnuSS

I did know what the AIR checks looked like. But didn't know the whole system now I do. Thanks nice breakdown

LS6427

iTrader: (2)

Just unplug it before you start it with a cold engine.....if it starts up and idles all messed up.....the MAF is good. Then while its still idling plug it in and it should smooth out in a few seconds. If it doesn't......shut the engine off and start it again and it should be smooth and normal. Do this when the engine is dead cold.

If your WOT is smooth and normal....the MAF is good.

.

GuardianMagnuSS

I've done that unplugged the MAF and it idles, revs down a bit and fixes itself. Never plugged it back in while engine still running.

LS6427

iTrader: (2)

I think you MAF is fine.

Check for vacuum leak.

Get the scan done for the 02 sensors.

.

GuardianMagnuSS

I'm starting to think so too Thanks

demonspeed

iTrader: (7)

Another good piece of troubleshooting advice.

GuardianMagnuSS

i should be good then thanks guys I'll see if it's a vac leak

garygnu

harbor freight has a hand held scanner for $100 that will check O2 sensors .

LS6427

iTrader: (2)

If you can't find a vacuum leak anywhere on the exterior.......some times the rubber head of the IAC valve deteriorates, then when the IAC is closed or almost closed at idle, a little air gets through it, unmetered air. Take the IAC valve out and make sure the rubber head piece is still intact and looks good.

Just take the torn screws out....slide it out nice and easy......look at it and just put it back. Don't start messing with it, don't push the spring, just look at it and out it back if the rubber looks good. They are very delicate and can fly apart if you mess with it. If you just take it out and put it back you cannot hurt it at all.

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LS6427

iTrader: (2)

If you have an original TPS it could also have a worn spot in it.....that can send improper signals to the PCM also, making the IAC valve open up more than it should for the given situation.....allowing more air in then it should be.

And at least with my engine once.....I had a worn TPS and I got no codes or SES lights. But replacing it fixed my issues. I just put a new one on hoping that was it and it worked. Because everything else looked fine and/or checked out.

It's another part you can buy to check....if it doesn't help, return it for a refund. Just tell them you never installed it.

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