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Discussion Starter #1
Yo there.

Yesterday I was getting back from the grocery when my IDLE became pretty rough.

The engine didn't stall but it was amazing how nuts the RPM gauge on the cluster performed. I pulled over for a moment and when I tried to get back to the street the car was completely out for power. As the 1st shift was engaged, the car kept jumping like a mad horse but the engine itself never shut off. There was also a strong smell coming from the engine bay, at first it felt like solvent (?) but now I guess it was just unburnt fuel.

Today morining I started the car and the problem was gone (?). Of course that was not enough to me so I kept rev'ing up the engine until the problem got back. This is what I was able to capture:


You can clearly see around 08s that I almost took the TBI to WOT but the RPMs couldn't follow it up. Then the IDLE became nuts again but the engine never stalled.

At first I was considering my ICM was gone as it seems to be a pretty common issue on the AEBs. A complete scan on VCDs now lets me believe that the MAF is the real culprit, though:

VCDS Lite said:
Address 01: Engine Labels: None
Controller: 8D0 907 558 E
Component: 1.8L R4/5VT MOTR HS D02
Coding: 04001
Shop #: WSC 05314
VCID: 33199CCF122D
1 Fault Found:
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-10 - - - Intermittent
Readiness: N/A
I was able to LOG both scenarios, first when the IDLE was nice (which I called healthy moments) and later the poor IDLE time which I called unhealthy moments. These are the graphics from Excel:




These results seem to be pretty obvious as the MAF sensors seem to freeze and make the ECU crazy as is tries to set the right amount of fuel for that amount of "air" which is fake. That's what makes the RPM so nuts according to my theory.

Right NOW, as I need the car running ASAP, may I just unplug the MAF to force the ECU work on a "default" mode? This will probably reduce my mileage as the car would run on much richer standard. My fear is that this could damage the engine or even the catalytic converter on short term.

At first I considered that cleaning the MAF could bring me some improvements but considering that the values are LOCKED (frozen) on negative values I'm pretty sure the unit needs to be replaced.

Any suggestions? Thanks!
 

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Discussion Starter #3
Could try cleaning it first. May get you by for awhile
TomK
I see. I'll see where I can track down a MAF cleaner around. We're in the middle of Carnival, a long holiday which will only end by Thursday.

For a while I have just unplugged the MAF and SURPRINSIGLY I've got "readings" from the sensor according to VCDS:



I'm pretty sure those are "emulated" values created by the ECU since there's no real MAF to provide them. Nevertheless, the IDLE is pretty good although I feel it a little damped. For instance, after keeping the RPMs on a certain range (~2500 RPM) if I suddenly remove the foot from the pedal, the RPMs slowly drop back to IDLE instead of dropping right away.

Anyway, I'll try to get a MAF cleaner and then I'll feedback this thread.
 

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Discussion Starter #6
Check the wiring, clean and check the connectors.
Hi Tom, I'm not sure how to "check the wiring". The conector is in pretty good shape and the contacts are really clean. I've got a LOCTITE contact cleaner around so I could try cleaning the connectors with it but not the MAF.

I've been searching around and lots of people say that MAFs are supposed to be cleaned with MAF cleaners only, not regular contact cleaners like this I've got.

 

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Do not clean the MAF with that or any cleaner that isn't specifically designed to clean MAF's. Checking the wires as in making sure they are in good condition. No cracking insulation, corrosion, breaks, being pinched. Etc........
 

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You can also use a meter to check conductance of each wire between the connectors. (at the MAF and the ECM)
Should be less than 0.5 ohms resistance. (note the fault is intermittent)

Use only MAF cleaner on the MAF sensor.
 

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Discussion Starter #9
Thank you guys for the inputs.

I did check the wiring visually and the connector that goes to the MAF looks in pretty good shape. I'm a little afraid of messing with wires to check their resistance as this would involve disconnecting/reconnecting plugs that are almost 20 years old and have lots of heat/cool cycles on their background.

I'll try to catch a MAF cleaner by Thursday, it's kinda funny as I couldn't even track one online. If cleaning it doesn't fix it, I'll order a new MAF from FCP Euro and they do offer both the BOSCH and this other brand called BREMI. Both of them are labeled OEM but I never heard about this BREMI before. Have you ever hear about it?

Thanks.
 

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Yeah, Bremi. This was the company that manufactured coil packs for all VWs beginning in late 2001. Almost as big a "fly in the ointment", from early 2002 through mid-2003, as Dieselgate is these days.

Give me a nickel for every Bremi coil pack ever involved in a recall, and I'll retire. ;)

Clean the MAF with some 90 Percent Isopropanol (Isopropyl Alcohol) "IPA" from your local big box store. It should have a red label; don't use the ~70 percent strength formula as it has glycerin (not good for the MAF). Place MAF in a clear plastic bag with ~250-400 ml of the 90% IPA. Slosh around for 5-7 minutes, then observe the liquid. If you see any debris settling from the liquid, dump it out and repeat until the liquid is clean/clear.

If still no success, I recommend conductance testing of each of the five wires that run between the MAF and ECU that Tomvw mentions in post 8.

If you drive for more than a couple days with the MAF disconnected, your cat (what's left of it) may end up being closer to toast from the overly rich mixture from running in "limp-mode".

Good Luck :beer:
 

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Discussion Starter #12
High Vitor, You should be able to get IPA from a chemist, pharmacy, or drug store; whatever you call them.
Nice! I'll go after the MAF cleaner first, if I can't get it I'll give it a shot with IPA.

Now, Electron Man said I could toast my catalyst for driving with the MAF unplugged. This would happen only for a 5 ou 6 times until I can get it fixed or replaced. Is it really so dangerous for the catalyst to dive in LIMP mode for, let's say, a whole month?
 

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This would happen only for a 5 or 6 times until I can get it fixed or replaced. Is it really so dangerous for the catalyst to dive in LIMP mode for, let's say, a whole month?
It depends. Five or six trips of a couple miles or less or five or six 25-40 mile trips over a month? MAF limp mode won't ruin your cat as fast as two cylinders not firing, but some people let one month turn into one quarter which next time you turn around, six months have passed. Just letting you know that procrastination on solving your MAF issue has consequences.
 

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Discussion Starter #14
Today I had a shop tour on a street known for having tons of specific auto repair shops and absolutely NONE OF THEM had this "MAF Cleaner" available.

Chatting around with the sellers (from more than one shop) they all seemed to be pretty sure that cleaning the MAF, even if it worked, would just be a temporary fix that would most likely turn against me on the worst time possible (probably while in the middle of traffic jam or while driving around unknown places at night).

Considering that the OEM part took almost 20 YEARS to die, I'm decided to go ahead with a new MAF from BOSCH instead of trying to fix mine by cleaning it or whatever. FCP is selling it for $ 129 so I'll just give it a shot. BR dealers charge R$ 2893.46, something like US$ 1,000, LOL.

I'll place my order tomorrow as I need my credit card balance to reset, ack! BBL.
 
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