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dscoobydoo wrote:On my car with the PP6, the FCD will cause the car to do that (when I hit boost pressures) when it is not working right. It bucks like a pony and sometimes wont give off a code.
It almost sounds like when you are going from closed loop to open loop it is doing something. That would be an ECU issue.

But there are a lot of things that could do that.

free5ty1e wrote:Knock sounds like ... like someone just threw quarters into the throttle, right? I haven't heard that. (I've actually never heard that... perhaps I should look up a Youtube video of engine detonation. And after all the cool videos that will undoubtedly follow, I will be sure and search for engine knock.)

Knock sounds like, well, knock.. It has a lower pitched tap, or tick sometimes. Definition of Detonation: Unburned end gas, under increasing pressure and heat (from the normal progressive burning process and hot combustion chamber metals) spontaneously combusts, ignited solely by the intense heat and pressure. The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure. Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration. It sounds like a higher pitches pinging.

No check engine light still - even though I still don't understand what the constant flashing during D-check mode was trying to tell me.

Good. Constant flash means you're OK and no codes are detected/being detected in d-check.

Crap - boost gauge jumps erratically in time with the engine's stumbling / jumping when at or under atmospheric pressure sometimes - car lurches about embarrassingly.

While your engine is stumbling your boost gauge WILL be all over the place.


So, I realize now that I probably haven't changed my spark plugs & wires for a good 40,000 km or more. Also, there were major oil leaks that eventually gave the wires a good coating (I think they are starting to swell). Then there was this whole situation where plugs 2 and 3 would keep getting flooded with fuel while the '94 ECU refused to provide pulse width to those injectors... do you think my plugs and wires could be in bad enough shape that perhaps 6psi at this point is more than enough to blow out the spark and cause "reliable" misfires? (oh, what a term!)

Honestly I have a feeling that new plugs and wires are gonna do a whole lot for the health and performance of your car. The plugs may just not be functioning well enough under boost to burn all your fuel.

I've also gone ahead and ordered a fresh crank pulley from Subaru and am going to go ahead and pay my mechanic the $25 it will cost in his labor to replace it for me so I don't have to deal with that one.

Good!! Also the crank pulley is not a fun job to do, especially by yourself. $25 is cheap labor.

free5ty1e wrote:
I mean will I have to move anything from the stock setup to access the spark plugs, other than the wires?

Nope, with some extensions and a sparkplug socket you have decent access to everything. Driver side head will be a little more crammed than the pass. side. Our SOHC heads aren't bad compared to DOHC, there is a lot less space and it's a lot more of a pain in the ass, lol.

Then, dielectric grease on the part of the plugs that go into the boots to protect them, and thread anti-seize on the plug threads.

you got it.

Gapping them to .039 - .040. The Subaru mechanic, who's used to working on WRXs and STIs, recommended I gap them at .022 or so.

I dunno what he's talking about, but out owners manual states plug gap to be between 0.039" and 0.043. Here's a little faq for you about plug gapping;

Bigger gap =
Positive side: larger spark, better ignition.
negative side: your spark can get "blown out" by the air passing by.
Smaller gap =
negative: not enough spark, bad ignition, stuttering
positive: your spark is hard to blow out.