2.8 not running so well

[99blueb5]

99 a6 avant 2.8tip, i have an occasional backfire and at low rpms in gear it stumbles and occasionally there is a decent amount of jerking and bucking but if i downshift to a lower gear its all gone, car stil hauls ass and gets 17mpg, i pulled codes though a cheap vag-com and got a random misfire detected cant remember exact # PO300 something. i cleared them and they will come back in about a week, when car is cold(under 160oil temp) it runs great and no problems and it seems a decent amount faster when cold, i had a cone filter intake and thought it was getting heat soaked so i switched over to the stock box and felt very little difference in how well it ran, what would it be? im thinking maf possibly, and ideas would be awesome

[A62TURBO]

coil packs are usually the first thing to look at with miss fires.

[_a6_]

from what your describing i agree a62turbo i think its the coilpacks that would explain the jerking

[oc-drop]

the 99 2.8 uses spark plug wires, so it is likely not the coilpacks like newer A6s have.

Have you changed your spark plugs? wires? cleaned maf? cleaned throttle body? cleaned air filter? checked vac lines?

It's probably one of those... but by now, being 10 years old, I'm sure the car can gain from all the things I listed.

[A62TURBO]

the 99 2.8 uses spark plug wires, so it is likely not the coilpacks like newer A6s have.

Have you changed your spark plugs? wires? cleaned maf? cleaned throttle body? cleaned air filter? checked vac lines?

It's probably one of those... but by now, being 10 years old, I'm sure the car can gain from all the things I listed.

shit, I didn't know that. you learn something new everyday.

[_a6_]

the 99 2.8 uses spark plug wires, so it is likely not the coilpacks like newer A6s have.

Have you changed your spark plugs? wires? cleaned maf? cleaned throttle body? cleaned air filter? checked vac lines?

It's probably one of those... but by now, being 10 years old, I'm sure the car can gain from all the things I listed.

do you know when they started using coilpacks? because i have a 2000 and when i went the dealership because my car was bucking they thought it was the coilpacks

[2001A6]

The 2.8 has coil packs. 3, with 2 wires each. they are in front of the intake manifold under the plastic cover. Then, it has wires running to the plugs.

[99blueb5]

plugs havnt been changed yet but i will be, which ones? plug wires look original but ill test the resistance in them to make sure, vacuum leaks very doubtful, i have cleaned the maf and way to test it i really think it it but still not sure, new air filter

[_a6_]

i have a question, my cats went out and im quickly trying to find replacements as my gas mileage has gone to hell and i was wondering if you guy knew if these would fit or not
http://www.performancepeddler.com/se...4605&x=15&y=12

really sorry about thread jacking

[oc-drop]

i have a question, my cats went out and im quickly trying to find replacements as my gas mileage has gone to hell and i was wondering if you guy knew if these would fit or not
http://www.performancepeddler.com/se...4605&x=15&y=12

really sorry about thread jacking

94605 sounds right...

you can go to magnaflow.com to double check.

[390wheel]

you cant just go looking for the problem like that. you have to know which cylinder is misfiring, then see what causes it ...

[_a6_]

94605 sounds right...

you can go to magnaflow.com to double check.

i searched with the part number and didnt find anything

[oc-drop]

i searched with the part number and didnt find anything

search by model/make

[idrinkv8]

It wouldnt hurt to throw some injector and fuel system cleaner through the system.

[_a6_]

search by model/make

2.25 inlet and outlet is the right size right?

[99blueb5]

which plugs do i need, already used injector clean several several times

[omegaboost]

So did you find the problem yet? I actually have a 01 2.7T 6spd and it seems to be doing exactly the same. I changed the maf, spark plugs, air filter, we checked all the coilpacks which seems to be working. injectors maybe??