SplitSecond S4

Recently my 2000 audi s4 has started to act up... After i start the engine and it begins its warm up, the engine will suddenly die/stall out. sometimes she wont start at all. knowing about common MAF problems, i disconnected it. Now The car will start.

SOOoo, I replaced the MAF and reset the ecu, yet the problem still exists. Any ideas as to what my problem may be? (the car was running great a few weeks ago)

thx for your time..

kbonarek

Have you scanned the car with vag-com yet? Might be some dtc's stored that could point you in the right direction.

K04-S4

Issues with G28 Engine Speed Sensor can cause engine to stall and not start, although a VAG scan should show a G28 related DTC if this is the case.

SplitSecond S4

scanned the car with vag-com, the coolant sensor code came up.
Sooo i replaced the sensor and the car seemed to start fine with the MAF connected.
I wish i could end this post by saying my problem was solved, i cant tho..
the engine wont stall now but it has developed a kind of "bucking" at idle, the engine will revv in between 700-1400 rpm..up and down, up and down. no codes are being thrown at the moment so im kinda puzzled. why would it be bucking like this? when i disconnect the MAF the buckin stops and the car runs fine (just no power). any ideas?

kbonarek

Is the replacement maf sensor you installed new or was it used? They're really sensitive to being dirty as well...I've heard of some people having success cleaning them with non-chlorinated brake cleaner.

And how does the car run apart from the idle problem?

K04-S4

I clean MAFs with 99% Isopropyl Alcohol.
CRC makes a professional MAF Cleaner so you could try that too.

Fluctuating idle is commonly related to intake leak / vacuum leak / faulty MAF.

SplitSecond S4

thx for the suggestions guys, this is bugging the hell outta me even tho its more than likely a minor problem. ( i just want her back really really bad lol)
yes the "new" MAF was a used part but i was assured it was working properly, probaly faulty, guess thats what i get for trying to save a buck. tried to clean it using the Isopropyl Alcohol but it still wont work. Im going go to audi tommorow to buy a new one and see if that works.

kbonarek

Don't get a completely new maf...you can buy just the sensor. Check out ecs tuning...they're not the only ones either. Do a bit of checking around...I think the sensor is around 60-80 bucks.

Or if you know of a larger maf for sale at a decent price, I'll sell you my stock one at a great price...

Anyway, all joking aside, only important thing is that you stay with the right sensor, whether it be bosch or hitachi.

Hope we can help you get it sorted out...I know how frustrating it can be. Going homebrew stg 3 tests your patience like nothing else.

Hang in there!

SplitSecond S4

WEll i finally got pissed off at this problem and decided to bite the bullet, i took the car to the dealership. They told me yesterday that my front driverside intercooler was leaking and had to be replaced . also my ecu had some minor corrosion that they have repared. im hoping those bastards are right cause my bank account is hurting... thx for your quick replys every1.

K04-S4

Intake leaks will cause untold quirky problems. You can make your own intake pressure tester for $20. I use it once a year and everytime the intake system has been opened up for any reason. You typically only need about 10lbs air to find a leak. Do NOT use unregulated line air pressure. If your running higher boost levels you can temporarily bump it up to boost pressure to find a minor / higher pressure leak, but keep higher pressurized time as short as possible.

http://www.awe-tuning.com/media/pdf/...ure_tester.pdf