aditsu4you

i have a 04 audi a4 1.8t fwd auto and it has a few problems that im trying to fo fix..

first of all wen the engine is on and the car is idling it shakes and rpm goes up and down randomly, i changed all spark plugs and ignition coils and didnt solve the missfires. plus the car wastes twice as much gas as usual because of the missifre i suppose..

i got it checked in different places and they all tell me different stuff so i dont know wich one to believe since i dont want to start changing parts that dont need to be changed..

some told me it might be an air leak, some said fuel pump, some said mass air flow sensor, and the last one i went to that seamed like he knew what he was talking about said its the throttle body positon sensor.

Another problem i have is that when im driving, the car all of a sudden goes in limp mode and then the car goes in neutral by itself and i have to stop the car, hit the break, and then accelearate again in order to work so i dont know if these problems are related or not

I need some advice in what part is causing these problems if anybody can help

lyleswk

Probably all related and could be any of the 3 items you list or something else. By the way, never heard of a bad throttle body position sensor, but that doesn't mean there isn't a first. Best thing to do is go to Autozone / Pep Boys and get a free generic code download or go to a reputable VW / Audi indie / dealer and get a VAGCOM download. That way you won't be chasing a bunch of parts and potentially wasting a bunch of money.

replayrnaudia4

pull the codes, any brand name parts store will do it free, had similar problem recently, see stalling post from about a week ago.

wheelmanbg

Have you changed your fuel filter lately?

If not, it's something cheap that you can try.

If your check engine lights is on, do what the other 2 said and have the codes pulled. Then we can be more helpful.

A4_in_CT

It sure sounds like a coil pack issue to me. What brand are your replacement coil packs?

My last bout with a bad coil pack was an STS aftermarket pack that lasted about 15,000 miles. It misfired a little on and off for 500 miles, never throwing a code until it REALLY went. I knew it was coming, I just didn't know which one to replace!

jordonb

Disconnect your maf... If it runs the same, maf is the problem, if it runs worse, maf is fine.
Vacuum leak could be a likely culprit.
As Lyle said, throttle position sensor is VERY unlikely. We have drive by wire, not cable, so it is different. If you have access to vag com, you can do a throttle body alignment.
Fuel pump will make some humming sounds before it goes, then when it is just about to die, when you hit the gas, it will feel like you are hitting the brake. I don't think it is your fuel pump though.

PKA469

if its the coil packs theres a recall on those. call your AUDI DEALER. My wfes A4 3.0 did that 2 times. misfiring. coil pack. called the dealer, RECALL..

jordonb

The original post stated that he already changed the coils.