After plain rebuild: hardly any power

[ST240]

Guys I'm completely at a loss here.

I rebuilt my RB26/30 due to spun bearings. Put it all back with stock components. While apart I changed/did the following:

-New ACL big end and mains
-Had the injectors cleaned and tested
-Cleaned the head with new seals / lightly lapped the valves
-New plenum gaskets
-Greddy adjustable cam gears in the stock position

I think that's it. This thing made north of 400 whp when it ran. It feels like it's making about half of that now. It idles fine and feels normal at light and part throttle. It builds boost normally but it is VERY sluggish and feels bogged down when in boost.

Things I've ruled out:
-Timing, 15* BTDC
-Knock, it is not accessing the knock maps.
-Cam angles, the dots are slightly misaligned (half a tooth or so) but this is only from me slacking the belt off as I had it too tight (damn RB30 conversions). It's been this way the last time it ran well.
-MAF voltage appears to be normal in nistune, however I haven't cleaned it this season.

In nistune, when comparing old logs, TP (load) ramped up exponentially when boost was built. Now it just goes up linearly and to a max of about 30-40% of what it was before. I seriously have no idea.

I can liken it to the difference in power when I changed from a terribly designed intercooler to a great one, except this is the reverse. Which is why I almost feel the next step is to check for rags in my pipes although I never put them in in the first place.

Anyone else have any ideas before I start to go down a rabbit hole?

Thanks.

[Yellow4g63]

Did you hit the burn to rom button when you were done messing with the car? If not just load your old tune then hit the burn to rom button to clear the memory on the board. I found that if you didn't do that the nistune acts weird and does crazy stuff.

[ST240]

Thing is I had to reformat my computer in the meantime. I MAY have the old tune. I was able to download the tune from the ECU. Seemed fine. And yes I agree, Nistune does weird s*** :/.

[Carl H]

make sure your itbs are opening all the way, we just had a problem with a vq35 swap where under full load the tb was only opening a fraction of the way leading to a 80hp loss.
also regardless of the conversion the cam gears should line up 100%, mine are dead on with the timing marks on the cover and the oil pump.

[ST240]

In order for that to happen the T-belt is waaaay too tight. Something is funky there. It's not a lot. It made 400 whp that way anyway :p. That's why I got the adjustable gears. SAU guys were having the same issue.

[ST240]

I cannot figure this out. Cleaned the MAF, checked for unusual boost leaks. Nothing. It builds boost and power ramps up till about 3500 or so, feels like its gonna go like stink and then boom power just hits a wall. It's also quite dangerous because load isn't going to where it's supposed to so AFRs are in the 13 range at full boost. Soon I'll be forced to scale the TP until I figure this out. :? . Very frustrating.

Gonna rip the bumper off and tear the IC pipes apart in a last ditch effort to hopefully find a blockage. Short of that, I'm open to suggestions.

[Carl H]

maybe you have a rag in the ic?
what kind of bov?

[ST240]

Stock recirc'd BOV. I'm gonna pull the pipes off and check because the symptoms to me are screaming restriction somewhere... But I highly doubt it.

[ST240]

Carl, how would one go about verifying that the stock rb26 cams are timed correctly. I've read your degreeing thread over and over and I understand it fully, but whats the point of reference for the stock cams? I basically want to take the marks on the cover plates out of the equation.

[Darius]

I was leaning towards verifying the number of teeth between the cam gear marks. It sounds like the mechanical timing is not right.

And degreeing your cams is independent of the marks on the timing cover and oil pump. It is referenced by a stop plug that you put into the spark plug hole. When you subtract the degree readings going both clockwise and counter clockwise, you know what the reference measurement is at TDC. On stock cams and cam gears at 0, there should not be a problem, which is why I'm questioning the mechanical timing being off a tooth or two. Did you count the teeth between the cam gears? I don't know off the top of my head what the number of teeth should be between the exhaust cam mark and crank gear mark though.

[ST240]

Thanks Darius.

My original concern was that I was able to line all the marks up, but with that, the belt was VERY tight. I slacked it off, thus unaligning the marks some (the exhaust more than the intake), which is why I thought I could make that up by adjusting the cam gears. I will check the number of teeth. I'm sure its on SAU or something. I see what you're saying.