Monthly Archives: July 2016

Nogaro S4

Nogaro stoppage

Today was the day I was tentatively to have tried starting the Nogaro.  I still haven’t put the exhaust together so it isn’t quite in running condition, but I had hoped to run it briefly to check on what Fault codes are still being thrown.  I’m expecting the brake pad wear sensor, washer fluid level sensor, possibly O2 sensors, and probably some random misfiring or other poor running indicators resulting from the base tune not quite matching the hardware.

Almost running
Almost running

One of the issues the person I bought the car from was having was intermittent starting, which they believed may have been caused by the clutch safety switch starting to fail.  They had bought a replacement switch that they gave to me, but when I got under the dash and investigated the switch I discovered that a prior owner had completely bypassed the switch, joining the two wires that normally would have attached to the switch.

Clutch Safety Switch
Clutch Safety Switch

I’m anticipating I’ll be spending a bit more time under here trying to understand what the previous owners were thinking when they started splicing into various wires.

Nogaro under-dash work
Nogaro under-dash work

One of my first efforts here will be to relocate the boost gauge to the Podi column mount – also supplied by the seller.

Unfortunately the intermittent start issue is persisting, though for the moment it’s not intermittent, it just isn’t starting.  I tried by-passing everything and having the engine turn over by connecting the starter to the battery, but even that did not succeed in turning the engine over.  I’m now suspecting the starter may be the culprit.

 

Testing

WMI Checkvalve

A discussion on water-methanol injection encompassed the subject of check-valves and their use with nozzles.  This further expanded to ponder the question of how much, if any, vacuum was present in the bipipes where WMI nozzles are most commonly located.

My personal experience has been that the flow rate through the Flow Sensor is different when nozzles have check-valves or do not.  What I have observed is a brief spike in the flow rate through the sensor upon system activation if the WMI system has not recently been operated.  I’ve attributed the spike to the system pump filling the lines, which results in a higher flow rate than is sustained once adequate line pressure is achieved, followed immediately by the WMI spraying into the intake pipes.

My assumption has been that when the system is not active and the car is running there is vacuum in the bipipes that slowly draws out the water from the WMI lines.  The discussion about check-valves raised this subject, and I decided to take a pressure reading of the bipipe with the car idling to find out if my assumption was correct.

I’ve got a Dwyer magnehelic differential pressure gage that is well suited to this experiment.  Drawing slightly on the low pressure port by mouth causes sufficient vacuum to move the needle, thus if there is vacuum in the bipipes this gage should be able to register it.

Dwyer Magnehelic Differential Pressure Gage
Dwyer Magnehelic Differential Pressure Gage

I decided to attach the gage to the car at the WMI bung that is located on the top end tank of the intercooler.  The position is near enough to that on the bipipes and would be easier to access since I did not already have a WMI line running to this location.

magnehelic_on_car

I used play-doh to seal the hose to the WMI bung.

Then I started the car and checked the pressure gage:

Gage reading at engine idle.
Gage reading at engine idle.

Nothing.  No movement from the needle at all.  I confirmed the hoses were sealed well and still no difference.  Inside the car the boost gauge, that is fed from the intake manifold plenum, was reading:

Boost Gauge at Idle
Boost Gauge at Idle

So much for my theory that vacuum in the bipipes is what was causing the WMI flow spikes that I recorded without the check-valves.

My new theory is that airflow past the nozzle creates a venturi effect that draws the fluid out.

 

Nogaro S4

More Nogaro Progress

Today I continued the effort of putting things back together.   As this is a repair and replace effort going on in conjunction with the buttoning up it’s taking a while longer than it normally would.

After the passenger side axle went in I also installed the new wheel well liner for that side.    I was also cleaning oil and dirt residue off the intercooler pipes and hoses so something like re-installing the IC’s entailed more than simply re-install the part.

I was pleased to observe that the accessory belt contained an Audi logo, I was concerned I’d find a no-name brand.  I had to hunt around for a little while in my spare nuts and bolts box to find a bolt to hold the AC compressor in place – a previous owner had chosen to install the part only using two of the three bolts.  I could see skipping a fastener or to on the wheel well liner, but not on something like the AC compressor.

nogaro_progress

I’m doing away with the K&N cone filter and BMW MAF housing, in exchange for and EPL MAF housing, adorned with 034 Motorsport stickers of all things, that was in the Nogaro’s trunk.  I’ll be reverting back to the stock airbox.

Another puzzling thing I found was that a prior owner had removed the bracket that the wiring harness attaches to beneath the coolant reservoir.  Without the bracket the harness hangs down closer to the exhaust manifold, not something I’m fond of, so I wrapped the harness in aluminum foil and tied it up underneath the the brackets for the reservoir so it has some protection from the heat below.

I still need to make up some joiner pipes for the exhaust, but I’m getting close to starting this S4 back and, and begin troubleshooting any remaining issues.