Today is the optional test but it was not even a question – we’re running it. The D1 was completed Friday and has only done a few laps of a kart track. The D2 was having a variety of small issues which combined to undermine Jonathan’s confidence in the car. We had to get a better handle on it. So this morning the usual – up at 3am, on the Mountain at 4am, set up in the dark, run at first light.
The sun coming up revealed the Mountain with nearly all the snow gone. A huge change from just two weeks ago.
It is actually warm even this early in the morning, and heats up from there. There are quite a few cars so we only get three runs. While both drivers post OK times (4:16 for Jonathan, 4:27 for Rodney), we have issues. Both cars are handling great, which is a relief. The tire size we tried on the D2 is working very well and we put it on our task list to get another set from Hoosier later today.
Unfortunately both cars have something going on with the engine. The D1 appears to be making little or no boost and is not running right, so Rodney is having to drive it like a momentum car. The D2 is running rough and by third run it gets bad enough that Jonathan just pulls over and shuts down shortly after leaving the start line. He does make it back to the pits when the morning is done. We take stock of the situation – much work ahead. We head back to the house and get to it.
On the D2, the diagnosis is quick (basically confirming a guess made in transit) – spark plug wires are burning up. Several are crispy and one is fully burnt and shorting to the exhaust. Fortunately we have many spares and have some heat-shielding to try so the ‘repairs’ are fairly quick.
The D1 is more difficult. First I have to wire up a boost gauge signal from MAP sensor to the dash so it can be displayed and logged. This takes a bit but is ultimately fairly straightforward. The only reason it wasn’t done to begin with is that other more critical things took priority in the short time we had. When the engine is fired up with the gauge there is no boost even when revving it. Now granted with no load it’s not unreasonable to have no boost, so that in itself is not a conclusive indicator of an issue. But the engine just doesn’t sound right and there is no audible turbo whine. So we start looking for culprits, beginning with the wastegate and proceeding to joints/fittings/etc.
Eventually the likely problem is discovered by Ray who is our guest senior crew member taking a short leave from his regular job as a rally race engineer. Turns out that when we installed a plug in the O2 sensor bung we used an aluminum crush washer under it for a better seal. The result (obvious in retrospect) was the opposite. The washer melted and blew away creating a significant exhaust leak just ahead of the turbo.
It takes a while to put everything back together and Ray’s experience definitely helps. Firing the engine up still doesn’t show much boost just blipping the throttle but we can now clearly hear the turbo. The consensus is that we definitely found a problem, we definitely fixed it, and we now have a way of logging the result. Since tomorrow is another test day (Thursday is when we qualify), we’ll test and see what we have. It will be the upper section so the highest altitude. We’ll learn something.