26 April 2018

While looking at the broken exhaust, the brace from the engine block that supports the turbocharger was found broken as well. I think I know when this happened. I was leaving a driveway and accelerated hard and may have caused a “PIO” (Pilot Induced Oscillation) with my foot inadvertently getting on and off the gas due to the car accelerating and decelerating so hard. The result was a violent back and forth action similar to ignition cut. I say I may have because the ECU failed to log it (again). Anyway, the turbo support bracket was repaired – though I noted that some bonehead had left it tack-welded, no surprise it failed.

As a temporary fix, the failed stainless bellows was welded back together instead of being replaced. That’s because even before this happened, there’s been a plan afoot to adding a muffler (again). The intent is to both reduce noise and unwanted attention, and to just be more pleasant. Besides, the car has so much power that if I lose 10 hp by adding it, so what. It’ll be installed so that it takes about a minute to remove for track event.The downside is more weight and heat, which will likely lead to something else that been on the back burner, a cold air duct running from the side vent to an enclosed air filter. As it is now, the open air filter sucks hot air in straight from the engine compartment, decreasing power and increasing the chance of preignition. Adding the duct may well make back whatever power the muffler takes.

In other news, a bit more information was found regarding CS-130D alternators. Apparently they contain a temperature sensor, though it’s unclear what for. It might be to reduce output to protect the alternator as it warms up, or maybe it’s to maintain output instead of it dropping off with temperature – I suspect the former.

Also alternator related, it was noticed that at idle, the alternator vibrates some. Suspecting something was broken, it was disassembled again but nothing was found, so the mount may simply be flexing. Might have to make a new one using thicker material, or double up the material that’s there now. It was reassembled with a new bolt and after putting it all back together, turning the alternator pulley now turns the engine (apparently it had to wear in) so belt tension’s off the list of suspects.

Right now I suspect it’s just how these alternators work, varying the output with temperature. An experiment would be to warm up the alternator with a drive, then while idling, cool it with compressed air to see if the output voltage jumps back up. My brother reminded me of something I intended to do, measure battery voltage with a good DVM instead of taking the dash/ECU’s reading as fact. Good idea, because the dash reads about 0.2V low, further lessening my drive to fiddle with this issue much longer.