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Tuesday, April 23, 2024

Doug's Domain

Doug Vetter, ATP/CFI

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Monday, October 30, 2017

Last Minute Diagnostics

A gallon of Redline D4 ATF arrived this morning so I took it over to my technician so he could finish topping off the transmission. I found him wrapping up the O2 sensor installation and watched as he installed the new alternator ductwork and ingeniously cannibalized a couple plastic rivets to create two makeshift washers big enough to secure the alternator duct cover. Another diagnostic confirmed that the O2 sensor fault was no longer present. The system briefly could not communicate with the transmission control module but another probe of the module succeeded and no faults were indicated.

I once again hopped in the car and was raised on the lift. Before we headed up to full height my technician had me put the car in drive and slowly accelerate. As the rear wheels started spinning the ABS annunciator illuminated in the gauge cluster, but this was normal and expected because the system did not detect the front wheels spinning. I soon felt a mild thud and watched as the RPM continued to rise. The transmission had shifted into second gear. Approaching 50MPH I felt another subtle thud and realized the transmission was now in third gear. With that test complete I carefully brought the wheels to a stop.

With the lift at full height and the vehicle idling my technician opened the transmission fill plug and proceeded to add another two quarts, for a total of 11, before the fluid began to run out of the hole. After reinstalling the plug and inspecting the underside of the vehicle for any leaks or any other issues my technician lowered the lift and I got out of the car.

Road Test

After connecting the diagnostics system one last time to clear the ABS fault code there was nothing else to do but take the car out on a test drive. Given my technician's vast experience it was clear he should be the one to conduct it so I rode shotgun. We proceeded to take a short trip around the parking lot and tested the brakes before we headed out on the test loop. While stopped at a light I noticed the idle at a proper 650 RPM and the engine idling smoothly. When the light turned green we accelerated onto the main road and I took notice as the transmission smoothly shifted through the gears. The 1-2 shift in particular was impressive in that it was refreshingly free of slop.

At this point I asked my technician whether there was any special test we would need to complete or any RPM we needed to exceed to verify the VANOS was operational and he said no. He added that if there was anything wrong with it a code would have been set when the engine was first started. Apparently that's because the VANOS is actuated continuously to facilitate easy starting and a smooth idle, as well as increased output at high RPM. He also mentioned that it is adjusted at engine shutdown to optimize timing for the next start, as oil pressure may initially be insufficient to actuate it. This may in part explain why the first start, while not horrible, was not particularly smooth. My technician then related VANOS works pretty well and that he's spent more time fixing other people's installation mistakes than replacing defective units.

As we reached the midpoint in the test loop my technician checked the heating system by putting the temperature controls at 90F, and then brought them back down to a lower temperature while he simultaneously turned on the compressor via the snowflake button. The A/C worked as expected. All the while the car continued to rev and shift smoothly and occasionally, when neither of us spoke, I was reminded of the wonderful symphony produced by the M3 exhaust.

I had earlier asked my technician what I needed to do to get the emissions control systems ready for inspection and he took this time to elaborate. While it is certainly possible to drive the car more or less normally and eventually get all of the systems ready, this requires multiple drive cycles. To get the car ready in a single drive cycle a specific set of requirements must be met:

  1. The fuel tank must be between 1/4 and 3/4 full, otherwise the evaporative emissions tests will not run. This is consistent with my recent experience fixing a leak in the system.

  2. The vehicle must be driven for at least 4 minutes below 30 MPH and 3000 RPM. This is best accomplished on a drive around the neighborhood within residential speed limits.

  3. The vehicle must then be driven for at least 20 minutes below 60 MPH and 3000 RPM. This equates to a leisurely run down the local highway.

In all cases the vehicle may be stopped as many times as necessary without violating the test constraints.

As we wrapped up the test drive and pulled into the dealer's lot my technician pointed out that he wanted to keep the car another day so he could do another leak check, adjust the parking brakes and wrap up all the paperwork so I agreed to come back tomorrow to pick up the car.

Next Up

After the inspection is complete and I'm no longer constrained in RPM I plan to stretch the car's legs in an effort to help seat the rings. Then I'll have to bring the car back to my brother's garage so I can align the headlights and apply some cosmoline to the brake and fuel lines running under the car. Once that is complete I should be able to return the vehicle to daily driver status and call this project officially complete.