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Discussion Starter · #1 ·
My 99 OBS is experiencing a bunch of problems that all seem to be related, and I need some help to figure out where to start with getting it sorted out.

First of all, its been swapped with a 2.5 out of a legacy/outback with dohc heads, but it's still running the 2.2 intake manifold and ecu. The previous owner did some tricks to make that work, and ill include some pictures in the replies.

I bought the car knowing that it was throwing p0325, and knowing that more often than not this just means a simple knock sensor replacement. When I bought it it was undrivable on the road because it was cutting power and just really slow. So I trailiered it home and replaced the knock sensor (which took some work because previous owner put a different connector on for some reason), and cleared the code and it seemed to get most of its power back, however, something was still off. Every time I drive it, I get backfiring under load below 2000rpm, in first and second gear. Not exhaust backfiring, but actual (loud) backfiring through the intake.

Now, it has this shitty short ram intake that either looks like the previous owner made it himself with spare parts or he got it for about 7 bucks on ebay, so I took that off just to examine the inside of it to see if there was any build up and sure enough it was absolutely covered in thick soot. I am eventually going to replace this with a proper cold air intake or a stock airbox if I can find one, but for now I just gave it a good cleaning and put it back on. Anyway, this leads me to belive there's probably a good ammount of buildup inside the throttle body, manifold, and valves too.

So, the CEL for p0325 came back on after about a week of intermittent driving, and although it's not completely cutting power like before, it runs like absolute dogshit below 2500 rpm, and has cold start idle problems. My plan as of right now is to start replacing things untill it shows signs of running better, but my main point of confusion is how this is related to the p0235 code, since as far as I understand it, that code is for the sensor/wiring itself, not an actual knock or ping. Maybe the backfiring issue is actually damaging the sensor itself?

Anyway, I plan on replacing the plugs and wires, MAF sensor, Throttle position sensor, pcv valve, and intake to start, and maybe pull the manifold and clean it aswell. If anyone out there has some insight or some suggestions for me, I'd really appreciate it.
 

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Discussion Starter · #2 · (Edited)
Here's a picture of the custom intake valve spacers so that the 2.2 intake bolts up to the 2.5
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Here's the custom cam timing gear made to work with the 2.2 cam sensor
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And here's a picture of the car because it sure is pretty despite the fact that it runs like shit
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And the engine bay
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Cool! I had no idea this was a thing. Diagnosing Frankenstein cars is absolutely awful though, P0325 will trigger if there is knock detected, or a problem in the circuit. If the ECM isn't seeing the knock sensor it has no idea how to advance or retard timing, and so runs like shit. I'd verify mechanical timing, and then look through the wiring for the knock sensor if you're certain it does not have knock.
 

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This is a whole lot of work to get

slightly more HP and slightly less torque

than the sohc ej25. Not that that helps your predicament, OP.

If you can't find anything electrically wrong, I'd recommend going back to either a 99-01 ej22, or a 99-05 EJ25.
 

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Discussion Starter · #5 · (Edited)
Cool! I had no idea this was a thing. Diagnosing Frankenstein cars is absolutely awful though, P0325 will trigger if there is knock detected, or a problem in the circuit. If the ECM isn't seeing the knock sensor it has no idea how to advance or retard timing, and so runs like shit. I'd verify mechanical timing, and then look through the wiring for the knock sensor if you're certain it does not have knock.
Thanks for this! I will use this for reference but my suspicion is that it actually does have a knock because it was still backfiring under load when the CEL was off. I'm going to check the spark plugs and timing belt this weekend and if they look fine I will start checking the wiring.
 

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Discussion Starter · #6 ·
This is a whole lot of work to get

slightly more HP and slightly less torque

than the sohc ej25. Not that that helps your predicament, OP.

If you can't find anything electrically wrong, I'd recommend going back to either a 99-01 ej22, or a 99-05 EJ25.
Yeah it's not the most logical combination I'll give you that, but from what I understand the guy was just making do with what he had. I have an ej255 from an 08-14 (not sure of year) wrx that I plan on getting rebuilt and throwing into this car at some point. I also have the original 2.2 block which came with the car. Honestly not sure what's wrong with it but I would much rather put my efforts into the wrx swap.
 

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This is a whole lot of work to get

slightly more HP and slightly less torque

than the sohc ej25. Not that that helps your predicament, OP.

If you can't find anything electrically wrong, I'd recommend going back to either a 99-01 ej22, or a 99-05 EJ25.
It is bizarre that someone would take one of Subaru's better engines, and replace it with one of the worst. But... I did a 25d bottom end with 251 heads because the bottom end of free, this could be a similar situation.
 

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Not sure, but those fancy machined adaptors would let someone run an ej20k or ej20g in a phase 2 car. Totally pointless these days, but about 10 years ago you could get those engines more plentifully.
 

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Discussion Starter · #9 ·
Pulled the side timing covers today and checked it. Drivers side looks perfect, pass side seems like it's half a tooth off but I'm guessing that's normal, correct me if I'm wrong. I also did plugs and wires this weekend, didn't make a difference, CEL is still on. Will be going through the wiring to the knock sensor next I suppose.
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