I have my STI, again. The repair costs have set me back by a lot. I can't let her go just yet as my other Subaru needs repairs. The car is acting abnormal as I have never had the DAM drop below 1.0. Maybe it's just bad gas from my recent fill up. Anyways, I'm in another break-in phase and it's just going to be broken-in and have the tune rechecked the moment it reaches 3k miles. Once it's cleared, it will be for sale.
After experiencing the same knock patterns which was happening during my spun bearing incident, it was happening again. It only happens around 4500 rpms. I had been suspecting a bad MAF sensor for a while, but I did not have money at the time and by the time I got it, it was too late. The bad sensor and running the stock manifold points to these being the culprits. I installed the new MAF and the car ran like it was fresh off the dyno tuned. The car feels really powerful and responsive while observing the break-in procedure.
My car had been plagued with knocking and misfires for the last 6 months. I've tried colder spark plugs to non projected and it still knocked and misfired. I did notice from day one, the car suffered from engine or alternator noise which can be heard through the old iPod integration and AM radio. It didn't affect the stock performance and improvements were noticeable when I added ground wires to the engine. Perhaps the alternator is going out. I did have success with voltage stabilizers with past project cars. They were a big improvement in drivability and added power. My guess is that the AE86(JDM) had a tiny factory battery, a 55amp alternator, and poor grounding. I didn't expect to see improvement with the STI due to it having a US spec battery, a high output alternator, and superior grounding. I was running out of ideas as I reduced gap, tried different spark plugs, new coil packs, running 91 octane, and injector cleaner. Then, with looking into EMI/RFI, I revisited the voltage stabilizers. I was going to buy a Sun hot inazma, but it was discontinued. The folks at Kamispeed substituted with the Sard racing electrical sweeper. That did the trick! A lot cheaper than replacing an alternator. I was suffering from EMI/RFI induced misfires and knocking. It was probably the culprit in messing with the MAF sensor, too.