Audi Repair: backfire\hesitation, fuel consumtion, airflow meter

Question
audi a4 avant
1.8  20v petrol
1998
134,000 miles
Not Modified


hi greg

i disconnected the (MAF) sensor then took it a drive down the motorway and to my suprise there was no hesitation what so ever, (little slow on acceleration which is expected)
when i returned home i parked the car and revved the engine to listen for backfire/popping noise coming from exaust on decelleration, and there wasnt any backfire/popping.

now im really happy because this is the first time it hasnt backfired and had no hesitation while engine is warm, i know i cant run car all time with (MAF) disconnected because it would destroy the CAT, plus fuel consumtion would not be very good at all.

so, do you think this is my prob? (faulty MAF sensor) if so how come it dosnt show fault code? and do they sometimes break down without showing fault codes? because i dont really want to spend £100 on new airflow meter if i end up with same symptoms (backfire/hesitation).


thankyou so much for helping me :)


Colin Fletcher.

UK.

Answer
I'm haapy to know that.
In US we have a lot problems with MAF sensors, I can say that only 50% set a fault for mix to lean but never anything about shotr or faulty MAF
When car is cold it runs on closed loop, that means ECM use its own program to make the car run. When temperature reach some point it change to open loop and it stars use all the sensors, that explain why is OK when cold.
On the newer cars you can run a test and check MAF but older ones don't have that. I know they not cheap but I think this is your problem. Some of them come rebuild from audi, but you have to give the old one back.
You can also drive it for a couple of days and see how it is, I don't think that it will destroy the CAT. Looks like when is connect reads more air, dumps a lot more fuel in the engine and that may  destroy the CAT.
Good luck   greg
US