I've put a couple thousand on my improper greasecar setup--no FPHE. I just finished installing a 20 plate heat exchanger today and I'm working on insulating my fuel and coolant lines. I noticed excessive carbon build-up on my injectors which spurred my doubt. The pre-chambers still looked fine and I ran it hard on petro-diesel for a few weeks to burn off as much carbon as I could.

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1983 240D 3.0T 4-speed manual, now sold

1989 Subaru GL Wagon 5-speed Touring Edition