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Flash635

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Discussion starter · #1 · (Edited)
2004 R5,

Is the air mass sensor Bosch part number FOOC 2G2 055 supposed to have a resistor on the outside of the body (but inside the actual MAF)?

My one doesn't and it looks like there was never one there but pictures of the part show it.
I think that resistor might be for petrol engines.

It was running like it had no boost at all. I got a MAF code so I pulled it out and a piece of what I think was a deteriorated air filter fell out.
I reinstalled it and the engine ran fine, maybe not quite as quick as it should or maybe that was my imagination.

After watching many Youtube videos I took the MAF of again and sprayed it with brake cleaner now I'm back to no power. I redid the codes but nothing came up about the MAF.
After I cleaned it I read somewhere else not to use brake cleaner. :censored::rolleyes:

I'm going out again now to run the codes (definition of madness)

Edit: No engine codes and the engine is still running like it has zero boost.
 
#2 ·
Touaregs are using hot film elements in their MAFs, in which the actual sensor material is "buried" inside the sensor's plastic housing and not accessible from the outside. The only part of the sensor that might be exposed is the intake air temperature sensor part, which looks like a resistor (and is actually one). Because these are combined sensors that contain both of these elements in a single unit.

However, the point is, that because the hot film part is hidden in the sensor, it can't be really cleaned, and even if you could touch it or get some caustic agent in contact with it, you most likely would just destroy it. So, whenever the sensor goes bad you'll just have to replace it. Well, at least in 99 of the 100 cases. The cleaning method only works on older, hot wire type sensors which have the actual sensor (ie. a piece of wire) exposed, and thus the latter is both accessible and also more resilient to cleaning agents and tools.

That said just because you have no power or no boost, doesn't mean it's your MAF that's bad. You'd need to log the MAF readings using VCDS and see whether it reaches minimum and maximum values and correlates with engine speed and such, to determine if the MAF is failing, despite the ECU possibly not yet realizing that. But the lack of power could be the result of a myriad of other things, including fuel supply problems, turbo problems, EGR problems, etc.
 
Discussion starter · #5 ·
Gnits said:
Touaregs are using hot film elements in their MAFs, in which the actual sensor material is "buried" inside the sensor's plastic housing and not accessible from the outside. The only part of the sensor that might be exposed is the intake air temperature sensor part, which looks like a resistor (and is actually one). Because these are combined sensors that contain both of these elements in a single unit.

However, the point is, that because the hot film part is hidden in the sensor, it can't be really cleaned, and even if you could touch it or get some caustic agent in contact with it, you most likely would just destroy it. So, whenever the sensor goes bad you'll just have to replace it. Well, at least in 99 of the 100 cases. The cleaning method only works on older, hot wire type sensors which have the actual sensor (ie. a piece of wire) exposed, and thus the latter is both accessible and also more resilient to cleaning agents and tools.

That said just because you have no power or no boost, doesn't mean it's your MAF that's bad. You'd need to log the MAF readings using VCDS and see whether it reaches minimum and maximum values and correlates with engine speed and such, to determine if the MAF is failing, despite the ECU possibly not yet realizing that. But the lack of power could be the result of a myriad of other things, including fuel supply problems, turbo problems, EGR problems, etc.
Click to expand...
It has no power as if there were no boost. It drives just like it did that time the charge pipe came off but I can't see or hear any leaking boost. The VNT works freely, the EGR is blanked off.

There was debris from a collapsed air filter in the MAF, and was getting a MAF code.
Removed debris and replaced MAF and it ran properly.
Took MAF out, sprayed it with brake cleaner and a Q tip and now engine runs bad.
No code. Pretty clear it's the MAF.

Picture of the replacement part show an exposed resistor where my one doesn't have one and it looks like it never did. I think the same part is used on petrol engines and they use the resistor. Same part number.
 
Discussion starter · #6 ·
TurboABA said:
So let's look at some measuring blocks or log the boost in order to determine if you have boost or not.
You seem to have a VCDS but are making some weird assumptions instead of using it to troubleshoot various components and to isolate your issue.
Click to expand...
The notebook I took the readings on won't turn on after a Windows update so I can't look at the logs. I'm almost 100% sure there was no boost problem logged.

There was debris from a collapsed air filter in the MAF, and was getting a MAF code, running bad like it had no boost.
Removed debris and replaced MAF and it ran properly.
Took MAF out, sprayed it with brake cleaner and a Q tip and now engine runs bad.
No engine code. Pretty clear it's the MAF.

I'm going back out with the multi meter.
 
Discussion starter · #8 ·
Gnits said:
Did you blank off the EGR? Did it ever run fine after the EGR has been blanked off?
Click to expand...
EGR is blanked off at the cooler end and has been running fine this way for about 2 years.
My model doesn't need any adjustment with VCDS after doing this.

I got my notebook started and looked at the stored codes: no code for the engine.
I've read where the MAF doesn't always send a code but what a lot I've been reading is in regard to petrol engines.

The thing is it started running bad after I cleaned the MAF.
I think I did 2 things wrong; Used brake cleaner and used a Q tip.
My original question was about the resistor.
 
Discussion starter · #9 · (Edited)
So, I tested the wiring with the multi meter.
Everything tested properly except for the return to the ECU.
Nice and steady at idle but the voltage doesn't change with the revs.

Now we know what happens when some fool cleans the MAF with brake cleaner and a Qtip.

New one is on the way.

It's still not showing a code.
 
#10 ·
I just saw a video on YouTube on cleaning the MAF sensor. There is actually a specific MAF cleaner that comes in a spray can. I too was under the impression that you cleaned those things with some kind of solvent like kerosene or, well...brake fluid. Guess not!

On my 2005 T1 I had problems with the MAF and I tried getting an aftermarket one (said Bosch on the box) and the engine actually ran worse than with the bad original one. So I ended up getting a used OEM one which made the engine run normal again. Moral of the story is: even though it's an expensive little bugger, but in this case buying OEM is worth it.
 
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Discussion starter · #11 ·
qurtuba said:
There is actually a specific MAF cleaner that comes in a spray can.
Click to expand...
I was going to buy a can of CRC MAF cleaner then my neighbhour who is a diesel mechanic offered my his can of carby and brake cleaner.
Even if I used the proper MAF cleaner I still would have used a Qtip which I now know is a mistake so I probably would have ended up in the same position.
 
#15 ·
Oh no! The curse of the aftermarket MAF sensor has struck again!!!
 
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Discussion starter · #16 ·
qurtuba said:
Oh no! The curse of the aftermarket MAF sensor has struck again!!!
Click to expand...
I went for the one that would deliver the fastest.
I was going to use the car for a 3000km trip next Thursday so time was important but I'm not going now.
I ordered the right one that will take longer to come but time doesn't matter now.

The Saab will get a workout now.
 
#19 ·
Oh! eBay wouldn't be my first choice for such a critical part given that it's hard to tell real from fake products on there, so I hope you will get a "good" correct MAF sensor that will last more than a few months.
 
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Discussion starter · #20 ·
qurtuba said:
Oh! eBay wouldn't be my first choice for such a critical part given that it's hard to tell real from fake products on there, so I hope you will get a "good" correct MAF sensor that will last more than a few months.
Click to expand...
I've heard a lot about dodgy ebay parts and people saying they'd never buy parts on ebay; a lot of reputable auto parts suppliers use ebay as a platform here.
Also between ebay's return policy and Paypal's protection and Amex's protection you (almost) can't lose.

This part actually does fit an R5 BAC engine, just not my one. Apparently there's another, earlier engine.

The second one is a used one from a known seller.
The photographs of the part show all the correct part numbers.

If that one wasn't there I would have gotten one from the UK or Germany.
 
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Flash635
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