Hesitation/raspy sound/power loss?
 

Hi all, my issue is a common one, and I've tried a lot of stuff, so please bear with me...

The problem is a sputter at higher RPM, above ~6000 I think. It's not a regular "hesitation" in the sense that when it happens, it's like a hit/miss thing. Imagine a hesitation that goes in and out quickly. When this is happening, it makes an unpleasant raspy sound.

When I start the car from cold, I'll get this sweet golden spot after it's reached operating temp (195f) for a few minutes where I can rev all the way up in 2nd and 3rd with no problems. After a few minutes, my problem described above begins. Even if I take it easy and let temps fall back to 195, problem persists.

2004 mt ~255000 miles
engine has ~135000 miles
BHR ignition with ~55000 miles
cat-less midpipe
no CEL, no codes

I tested 5 solenoids under the hood, with and without added heat. They all actuated fine for my bench tests.

I manually actuated the SSV while I had the upper manifold off. Seems fine?

Replaced the fuel pump with new oem. Seems to have made just a minor improvement.

Checked and cleaned plugs. They're fine.

Cleaned MAF. No change.

Cleaned ESS. No change.

Changed air filter. No change.

"Carbon cleaning" with Seafoam. No change.

It is a "low compression engine." All six faces are between 65-75 psi. I was ready to just chalk everything up to that and be done with it. I am currently hunting for my next engine...

However... last night I ran out of gas. My gas gauge has been lying to me for months and I forgot -- but after I put gas back into it, now all of a sudden this sputtering problem seems to have gone.

But I know the problem will return, so I know I still need to get to the bottom of it.

So, I'm looking for advice. I've got obdii scan tools, but I don't know what counters I should be watching, and what I should be watching for. For the past few weeks, I've been watching my wideband O2 and comparing it with AFR commanded and actual. But honestly, I don't know what those values are supposed to be, so all I can say is that the sensors are operational.

Anyone got ideas or insights?

you already know the problem. anything else is just a bandaid

http://www.rx8help.com/img/compression_chart.png

I know that is a problem, but I'm not convinced it's the problem.

this makes as much sense as stabbing yourself in the femoral artery and asking why you are bleeding out. low compression is low compression and needs a rebuild

Guys, I'm not disputing that it needs a rebuild.

But I'm still curious about the specific symptoms I'm talking about, because there are some indications here that they aren't being caused by any underlying low engine compression problems. If this is the case, then I'd like to know it. Really, I'd like to know how to diagnose it properly.

To rephrase it slightly: If running out of gas makes the problem go away, for whatever reason and for however long, then the problem isn't being caused by low compression in the engine. If this is the case, then I'd like to know.

I've had this car for 10 years and replaced the engine once already. I do all the work myself, and I love this stupid thing. It's my daily driver. I'm not trying to cheap-out of an engine replacement.