MAF Problems - Please Help!!!

[dave45090]

Ok guys.....I'm posting here even though my car is a P5 on the outside she's a MSP on the inside. (thumb)

I've attached my mod list at the bottom to help diagnose the problem.

After going to a "modified" stock MSP turbo setup 2 years ago, I've had a problem that I've been able to deal with but now will not go away. Whenever it rains really hard and there is standing water my car stalls and wont restart properly. The car turns over but with any load/gas it bogs and shuts off. The fix is to tow it home (thank God for AAA) and let it dry out. Give it a few hours (up to 12 hours) and I'm back on the road. Two weeks ago (the weekend of the floods here in Nashville) it happened again but this time it's down for the count. It threw a cel code (I dont' have the code in front of me right now, I'll post it later) that points to the MAF or MAF Circuit Intermittent.

I purchased and installed a new MAF and the problem still occured. I unplugged the sensor and sure enough the car fired up and was driveable. It ran like crap but it still drove....which it would not have if I plugged the sensor back in.

Does anyone have any suggestions? Do you think it's in the wiring or the the ECU? I would really appreciate your input and help. That's what makes this place so awesome!

Mod list that pertain to the problem:
Stock MSP ECU
FMIC and custom hardpipes
SSAFC V1 (note: it has not been properly tuned, drives great in the cold and just ok in really hot temps)
HKS blow off valve 8 inches before the MAF
Adjustable cams and J-Spec FS-ZE intake cam shaft

 

[dave45090]

Oh yea.....forgot to mention I didn't drive through a flooded area. It was raining really hard though.

 

[ghaze24]

My car does this too from time to time when its really wet out, it stumbles and stalls with light pressure on the gas but it always starts right back up and its fine. I don't think its happened more than a handful of times and I've never tried unplugging the MAF because it always starts back up.

 

[dave45090]

Anyone else? Can someone provide input?

 

[KrayzieFox]

I can't say I'm familiar with the issue whatsoever, but it's clearly a MAF issue as you're already determined. So let's start with the basics.

Is the MAF oriented properly? Arrow on side pointing in the direction of airflow?

 

[MSP-2003.5]

good point, i saw a pic on here of somebody's engine bay and they had it backwards.
also, is it a relocated MAF?

 

[dave45090]

It's installed properly. Thanks for trying to help though.

Anyone? I'm almost to the point of taking it to a shop.

 

[KrayzieFox]

Are you clamping or modifying the MAF signal for tuning purposes? SS AFC? Voltage clamp?

 

[SIBalla23]

Pull the carpet on the passenger side under the dash and check to see if its wet. Its possible that the ecu is getting wet. Just a quick check since I have heard of many proteges having a damp carpet over there in that spot.

 

[KrayzieFox]

Oh man, good suggestion SIBalla!! I JUST dealt with this problem today on my MP3. It didn't develop into anything serious, but it could have, so I took care of it right away. I started noticing that when it rains, the car gets a really damp smell and when I lifted the passenger side carpet by the ECU there was all sorts of moisture built up.

So I took off the fender to make sure the drains behind it weren't clogged, and holy hell was it gross back there!! There was all sorts of leaves and other crap behind the fender, but the real problem were the drains. They were so clogged up that when I filled the area under the windshield with a hose the water would back up and spill over through a small hole above the blower motor and make its way down and behind the carpet to the area by the ECU. So I ran the water through the top slowly while using a thin piece of metal shoved up the drain/crack to slowly clear things up. The drain is right above the black grommet in the second picture attached. Problem is now officially fixed.

You, and probably anyone else reading this, should check out the ECU area for moisture as mentioned by SIBalla. If your carpets are all gross and wet, then chances are your drains are clogged like mine were.

 

[dave45090]

Problem solved!!!!! I can't tell you how happy I am to have her back and running.

The problem was the MAF sensor. I replaced it with a new one. However....it wouldn't start because the battery was dead and the MAF wouldn't report to the ECU properly while attempting to jump it. The ECU was reading the MAF low voltage. New battery, reset ECU and problem solved.