2000 Passat MAF cleaning

Aug 31, 2004 5 Replies

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Ron and Tina Reyes 21 years ago

Got a question for those more experienced with the newer cars. In the old days I used to be able to clean the throttle plate on my GTIs, Jettas and Passats with carb cleaner. I'm currently getting a constant CEL on my wife's Passat (P1128 code). My Bentley manual says that code means: Long term fuel trim B1; system too lean. I fixed a bunch of broken vacuum lines, cleaned out the snow screen in th intake box and checked for more air leaks around the engine bay. I then reset the CEL but it keeps returning. I'm hoping that it is not the MAF because I am past the 70,000 mile warranty period. I've read that I can clean it but I want to make sure that I don't damage it. Can I use carb cleaner or do I have to use an electrical contact cleaner? Is this a PITA to do?

Thanks in advance.

Ron

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Woodchuck 21 years ago

There's a special cleaner for the MAF which most auto parts should have. Will it fix the issue, I don't think so. What is the display values in

01-engine, 08-block values, then 032?

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DriversWantedTech 21 years ago

The data displayed in 01.08.32 is the additive (idle) fuel trim and the multipicitive (under load) fuel trim. MAF readings are in 01.08.02 - field

3, I think.

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William Maslin 21 years ago

No, don't use contact cleaner. It has a lubricant in it. You want a zero residue contact cleaner for the MAF. I got some at Radio Shack. It was made by CRC. But Woodchuck is the man here. Pay attention to his advice.

Bill

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Ron Reyes 21 years ago

Unfortunately I do not have a VAG-COM. I am working with an OBDII reader and Digimoto software (yes, yes I know I should have a VAG-COM but I don't have the bucks right now). With what little functionality Digimoto gives me I can see the airflow as the meter is reading it. At idle (800 rpm) it is at

2.5-2.75 grams/sec. At snap throttle I'm seeing a max of 55-60 grams/sec. It's funny, after I reset the light the car runs beautifully.... for about a day. Then it throws a CEL and runs like crap at anything above 2000 rpm. Thanks for taking the time to answer my post. Sorry I can't give you more (VAG-COM) info...

Ron

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Charles DH Williams 21 years ago

Roughly speaking air density is 1g/litre. A naturally aspirated 2L engine at 800 rpm and 20% load will use

1 [g/litre] 2 [litre] * 0.5 [/ rev] * 0.2 * 800 [revs/min]

---------------------------------------------------------- = 2.67 g/s 60 [min/sec]

and at full throttle, say 85% load, 6000 rpm it would be 85 g/s

So, I would suspect the MAF of under-reading at high airflows. Contamination is an obvious possibility.

Charles

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