Category Archives: Maintenance

Fuel Filter & Pump Swaps

The silver S4 got a new fuel filter and fuel pump.

Audi B5 S4 Fuel Filter Swap
Audi B5 S4 Fuel Filter Swap

Neither of these is a task I enjoy doing, and when the fuel filter started leaking gas after being tightened to the advertised torque I was not happy.  Finding that I could not fit a wrench between the banjo fitting and fuel filter had me even more steamed.  Unable to find a suitable wrench I had about resigned myself to shopping for a new wrench with a thin body when I thought I might be able to get a good grip on the fuel filter with an oil filter wrench.

That hunch turned out to be a successful idea and the extra little bit of tightening the banjo bolt stopped the gasoline leak.

This car is also receiving a fuel pump upgrade with a ProjectB5 setup.  The fuel pump turned into a bit more effort than the “drop-in” name would suggest.  For the life of me I could not get the pump holder to engage with the basket.  This is the fourth time I have swapped pumps in one of these S4s and the first time I have had a hard time getting the pump in place, other than the first when I had not yet purchased the Schwaben fuel pump removal tool.

After 45 minutes of trying, and cursing, I decided to pull the pump out and try to figure out why the darn thing would not lock in.  Comparing it to the recently removed stock unit I noticed that the sock on the bottom of the PB5 pump seemed to to extend a little further than the stock part.  I pulled out the calipers to measure and sure enough the PB5 setup extended down 17 mm further than the stock part.  While the location makes it hard to be conclusive about the cause, it seems likely that the added length is preventing the fuel pump holder from descending far enough into the basket for the notches to engage properly and hold the pump firmly in place.

The next hurdle was a do-over on my part as I forgot that Audi wires the fuel pump backwards, the RED wire goes to the negative post and the BLACK wire to the positive post.  I wired up the normal way and got nothing when I tried to start the car.  Out came the pump so I could swap the wires, but happily upon re-installation the car started right up.

The car is on the base tune but is looking pretty good thus far.

CP Initial Boost Profile
Initial Boost Profile


Clean up and repo

Having finished with the driver side front corner yesterday I started out today’s effort by taking care of some house cleaning in preparation for rotating the car.  I’m moving on to the passenger side front wheel-well and the position the car was in was not conducive to working on that corner.

B5 S4 Clean up and rotate
Clean up and rotate

After straightening up I swung the front around (on the dollies) to give myself some work space around the passenger side.

Audi B5 S4 Passenger wheel-well work
Passenger wheel-well work

The rear lower control arm ball joint was quite troublesome, but eventually I got it loose.

Tomorrow I’ll finish removing the lower control arms and set to work installing all the new parts.

Front Driver Side Wheelwell

While I am waiting on some additional parts to be able to commence installing the K04 turbochargers on this S4 I have been directing my efforts at refreshing and upgrading the suspension and brake components.  The past couple of days I’ve been working in the driver side front wheelwell.

Today I wrapped up a bunch of parts swaps.

Audi B5 S4 Suspension and Brake Upgrades
Audi B5 S4 Suspension and Brake Upgrades

Starting at the bottom and working the lines counter-clockwise  we have:

  1.  Both lower control arms (balljoint on the front was a blast trying to get out.)
  2. Swaybar end link
  3. Brake rotor
  4. Vogtland Coilover (Had to visit Autozone to borrow a spring compressor)
  5. Brake pads
  6. 034 brake line
  7. Tie rod end (Surprisingly pesky putting the new one in)
  8. Upper control arms (Neither went in willingly)
Audi B5 S4 Slotted Brake Rotor
Audi B5 S4 Slotted Brake Rotor

The turbochargers have arrived.  I was mistaken about them being Genuine BorgWarner, they are a K04 rebuild from Midwest Turbo Connection.

Midwest Turbo Connection B5 S4 K04
Midwest Turbo Connection B5 S4 K04

Next up will be to check and set the preload on the wastegates to 8 psi so I can take a short break from the suspension and brake work.