hey recently got a 98 a4 2.8 and having some issues

bad fuel economy
literally no power at all 0-50kmh take 30 seconds and on the highway maxed out at 105 kmh
when starting will just die unless i hold the gas pedal for 4 minutes than will have a super rough idle

brought it to the shop with the cel came up as
p1602
p1559
p1545
p1198
p1199
p0102
p0160

shop said i needed both the rear 02's and the tb for 1300ish and a maf which was 500

before this
the battery was dead but got a new one
also new alternator in it
after i bought a new maf and out it in and still rough idles haven't driven it cause the acceleration is still the same

are the rear 02's just for fuel economy? because at the point my focus is to get the power back so its actually derivable

thanks any help is much appreciated

 

First of all, clear them all then read them when they come back up. 1602 is a low voltage and is probably left over from the dead battery.

0102 is about the MAF, could also be tripped by the low voltage, but also could be a leak in the intake system - air getting to the motor that the MAF never measured.

0160, 1198 & 1199 are all about the post CAT O2's. All they do is test to see if the CAT is working. They aren't causing your problem.

1545, 1559 are all about the Throttle Control Valve and Idle Speed Control. I have the feeling that's your real problem. But you really need a Bentley to walk through diagnosing that.

Do not throw post-CAT O2 sensors at the car if you're trying to fix the throttle response problems.

 

ya all the codes have been cleared and came back on but havent had access to a vag com yet, im thinking i might need a throttle alignment and cleaning or a new cat (hopefully not)

 

Hi. If you replaced the battery, then the throttle normally has to be re-adapted to the engine ecu, because the ecu loses the learnt/stored values . This can only be done with a compatible diagnostic tester. This would give you poor running symptoms.

 

Maxes out at 105 kmh (65 mph)? That's about half of normal top speed, so your engine is roughly making 1/4 of normal power, or less than 50 HP, so something is seriously wrong. Mtroxel guessed throttle, and that may be correct, but not account for the bad fuel useage. Disconnect the MAF and see if any improvment; if so, then the MAF is very dirty or has electrial issues. You really would benefit from VAG-COM, to check throttle operation, MAF sensor readings, and the coolant temp. A shot coolant temp sensor can really foul-up starting, power, and mileage.

 

i just put in a brand new maf with no results, so might be tb?? power like that could be the cat(?) but no codes referred to that, i timed 0-30 kmh (18 mph) took 12.5 sec...

 

You put in a MAF on a guess, this is going to get expensive. As TURBO410 said, you need to VAG-COM that thing to see what's going on. It sure is cheaper than guessing at the next part to buy.

 

i did vag it and those are the codes i got

the o2's wouldnt have affected the performance so i put in the maf cause it made sense but no diffrence

 

OK, I think it was the list of codes that started with a 'P' that made us think you had only used an OBD. Go over to Ross-Tech and look up those codes. Their code Wiki is pretty good.

Category:Fault Codes - Ross-Tech Wiki

I'd forget the O2 sensor codes till you get it running right. This is about the throttle body or the MAF, or some huge amount of air leaking into the system post-MAF. But I also find it odd that Terminal 30 voltage is still low at the ECU, even after you've cleared all codes since the battery replacement.

 

yea i cleared the codes after the new battery so im guessing it was just prexisting