Low power until 6500 rpm
 

So, I'm still having the same issues with my rx-8 that I've been having for a while. To recap really quick. When I bought the car (5k miles after reman was put in) it wouldn't redline easily most of the tjme and would miss at 7500 rpm or so before slowly getting to redline. Somehow I guess me driving the car like a complete and utter jackass fixed that and now the car smoothly goes to redline. The car is down on power, has been since I bought it, at least missing 50-75 hp and 40 lb ft of torque from my estimates (9-12 second 0-60 times) until around 6500 rpm where it feels like a those old 911 turbos that had no power and suddenly would break traction due to the surge (yes I break traction in the wet when 6500 kicks in). My fuel trims were at 11% at idle a while ago and I had an intermittent p2070 and a few other intake valve codes, now I'm up to 18% and a consistent p2070 code. I've cleaned the maf multiple times to no avail, I no longer have a cat (bhr midpipe) and the only misfires I have are in 6th gear at 5k rpm on the dot at minimal throttle(cruise control) and only when the engine is relatively cold (within 15-20 minutes of startup) and then no problems. Car also "coughs" on cold starts every now and then while idling. I've checked and replaced plugs coils and wires. Ssv and the other valves all seem to be working (havent been able to vacuum test yet and I have no clue where to hook up the pump in that engine bay so I'm still searching for info on that)

I keep getting the feeling that its a vacuum leak and I can't find it anywhere (smoke test came back negative) compression is low but within the acceptable range (front rotor is lower than rear but still have some life left) I also notice my exhaust sometimes has a blueish tint (I know that means oil) and my oil consumption can be as high as a qt every few hundred miles or so (I do drag race my car at every traffic light though and pretty much have the pedal to the floor whenever I'm driving it)

if anyone has any sort of idea what is going on I'd love some help! I've only seen 2 other people have this exact same problem on this forum, one never found out the problem from the thread(not specifically created for the issue) and the other never got a reply to his thread.

I had something similar and it turned out one of the vacuum solenoids on the back of the UIM was bad. Electrically, it was fine but it didn't hold vacuum in the off state. This caused a mild vacuum leak that was impossible to find and a weird power surge somewhere above 6500 RPM.

Take out those solenoids and pull vacuum on them to see if they still work.
This the diagram/testing procedure at the bottom of this page.
SECONDARY AIR INJECTION (AIR) SOLENOID VALVE INSPECTION
You want to pull vacuum on port "A".

oof... I'm going to try to get to them without taking the intake apart (although I planning to replace it soon). Would a failed solenoid cause my LTFT to be so high at idle? I thought that they only used vacuum to open up at certain rpm (I might be wrong in my understanding of how these work)

Without voltage applied to the pins, the solenoid seals off vacuum to the vacuum actuator. Applying 12v to the pins, it connects ports A and B.
If the solenoid's internal seals are bad, it can connect A and C. If that happens, you have a vacuum leak. You test that by pulling vacuum on port A of the solenoid with no voltage applied.

Removing the UIM isn't that difficult and it's a hell of a lot easier than trying to remove the solenoids without removing the UIM.

That makes so much more sense now! The reason why I didn't want to take the manifold off was having to get new gaskets and stuff for it haha (I'm really lazy, I'd rather work at something for hours than actually have to do more steps, even if in the end I do end up making things super complicated. People used to tell me I like to scratch my left ear with my right elbow lol)

any idea what that is in the picture (circles in red)? Seems like some sort of vacuum line to me and it's being pinched a little further back by the manifold in between what looks like the first 4 ports of the manifold and the last 2. Is that normal? Also any suggestions for my always wet of oil filler neck? (No, it's not from me spilling oil all over it and you can see it pooling on the ledges)

guess I'm taking the manifold off to figure out that hose now anyway, just wondering if that might be causing some sort of issue too

edit: am I an idiot? Or is that the vacuum line from the ssv? If that's the case I think I may have found my issue, the thing is totally clamped by the intakes (what are the chances I can get mazda to fix this for free since they're the last people to put this thing back together after a rebuild?)
https://cimg7.ibsrv.net/gimg/www.rx8...020e128e3e.jpg

The gaskets are just rubber o-rings. I've had mine off and on a few times and never had a problem re-using them. Obviously, if they're dried out, falling apart or otherwise damaged, you should replace them (and probably needed to replace them even before removing the UIM).

It's hard to tell what hose that is in your photo. The only host that I can think of that runs that direction that close to the front secondary port runner and alternator is one of the vacuum hoses for the SSV or VDI actuator.

How long has it been since Mazda touched it? If it's only been a couple of weeks, then you might be able to convince the service manager of the shop that did the work. If it's been longer, then it's probably not worth the effort.

over a year and a half. I bought the car 4k miles after a reman got put into it by some dealer who knows where in like tennesee? I bought the car in washington state and I live in NJ. I did call mazda a while back and told them my issues (reman comes with 1 year 12k warranty and I was just past that one year (close to 1 year 7 months now) and they said they might be able to work something out with me if it does turn out to be a problem with what they did so I'll give them a call and check.

I looked deep into that engine (geez it's so hard to lan over the car because everything bends and moves under my weight) and its connected to the ssv actuator port.

you just made my life 100 times better, I thought I'd have to be scraping off bits of gasket after I took the manifold off. At this point I'll just do it myself and see if that fixes the issue (I'm guessing clamped hose means ssv can't open)

That looks like a rodent chewed on that manifold.

what part? What do you mean?

The top of the manifold - circled in red - doesn't look like a port - it looks like something else.

here
https://cimg2.ibsrv.net/gimg/www.rx8...bbc15d4669.png

that's just the gunk that got transferred to my hand when I kept trying to test the valves haha

so I got the hose out of the intake (painful process without removing the strut tower on the s2). And the thing is clamped shut in 4 different places. So... I'm waiting for a replacement from mazda which will be here in a week and see if that fixes everything... now I just need a new transmission (grrrr, apparently I have an early vin with weak 5th gear and now it's grinding at high rpm shifts to 5th...)

Just an update, that hose has some life left to it (I managed to tear it a bit so there was a vacuum leak and it wasn't operating the ssv), after "fixing" that tear, I now don't have this giant power surge anymore and the car feels faster altogether (I don't need to downshift to 3rd gear from 6th on the highway to have a hope in passing anymore lol) mazda said the part is on backorder (figures...) does anyone know the exact part number for the ssv vaccuum hose? I'm seeing different diagrams give different part numbers and according to mazda none of those "fit my car" based off the vin (those are in stock and I can order them anytime)

Vacuum hose is vacuum hose. Just get some generic vacuum hose of the correct diameter and use that.

gotcha! Sadly autozone nor AAA have it and if napa doesnt either I'm stuck. Thanks for all the help so far everyone!