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Recently wired up my 20g (3B ecu) and just have the wires laying out loose on the car, just trying to fire it up, history is rebuilt motor (new rings, every seal replaced, valves re-lapped, etc. nothing out of spec during build, timed in w/sti belt pn: ST130284S000, not sure if 2.0l or 2.5l belt)

at first it was firing, on and off back firing in the intake, and the manifold plenum would get relatively hot and the block cold, i've gotten it to the point where it fires out the downpipe (very loudly) every second or so and not so much back firing really at all, the downpipe will get very hot and the intake manifold not warm

subaru dealer tech friend looked at it, said it was timing, he timed the motor in, no difference, told me I bent a valve, did a leakdown test, all cylinders are at 5%, saw somewhere that spec is 3% but still 5 isn't terrible, compression is 130 all cylinders, didn't drip oil in to recheck, I know that compression is low (spec is like 140-170) but should be high enough to at least start, I don't think I bent a valve-there was one evening combined cranking time was about 3-5 minutes and never once did it backfire, would have if the valves were bent-reasoning for that thought backed up by the leakdown

tried swapping stock (but new) 20g coils with each coil, no diff, tried old NGK's, no diff, tried gapping closer (28), no diff, using IK22's now and since beginning, maf is ok, tried on running 97 2.2l, also swapped a known good igniter from SR20, pull the plugs and all smell of fuel, sometimes dry sometimes wet some, fuel pressure is 40-42psi from walboro 255lph, drops off to 32-34psi after pre-start prime stops-thought that was sort of weird

no ecu codes, used Suberdave's diagrams for the engine, his UK & JDM wiring diagrams, these are different than every other diagram I have seen so far, his UK diagram matches almost everything else, except ursalia, his seem slightly different than those, these JDM diagrams I used are also the only ones I found where I could find match and identify every wire by color and terminal number/location

any help is really appreciated, I'm running out of ideas, I really think I may have a wiring issue

I also pulled the cam covers, went around to every cylinder at TDC for the particular cylinder and checked the cam lobes weren't pushing the valves down, checked with a feeler gauge also between the lobes and lifters, not really much gap at all, nothing that would indicate a bent valve, also verified each cam in correct place (R IN/EX, etc) and they're all where they should be, cam wheels i'm certain are in correct place, can only go on one way (notched)


anyone have any spare V2 ecus sitting on the shelf? (mine's a 3b for reference)
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