2006 Mazdaspeed 6 bogging at boost

[_UsUrPeR_]

Thanks for the ultra quick response!

The needle in the spill valve can be pressed in with the tip of my finger with no resistance. The button valve as well feels springy with no catching/hitching.

 

[Enki]

Could be PRV then, or internals sticking or something.

 

[_UsUrPeR_]

Well hey, thanks for your help. I'll report back with new logs after I replace the PRV

 

[_UsUrPeR_]

Alright. I have replaced the PRV with a used one from another vehicle. I have disassembled and cleaned the HPFP. After starting and idling (Datalog43.csv) everything seemed relatively normal. There was a hitch in the idle a little bit (sounded like it was searching for a good idle point). I am noticing in the log that spark advance is confusingly all over the place, which I would consider strange at idle. Datalog44.csv still idling while it comes up to temp, checking for fuel leaks, etc.

Main issues are Datalog45.csv. I tried driving the vehicle, and it hasn't really changed much. At 75 seconds, I try a WOT pull, and fuel delivery is clearly not there. HPFP Act. pressure showing ~70PSI.

After that attempt, I swapped out the spill valve from my old HPFP, thinking that might be the issue, but it still behaves the same.

I have another HPFP I can throw on. I am thinking that may be the issue. Something in HPFP body perhaps?

Any suggestions, please let me know.

TL;DR: disassembled and reassembled my HPFP. Removed old PRV and installed a used one that I had on an old engine. Looks like there's still a fuel delivery issue. Replaced spill valve with a used one in the hopes that was the issue. No dice. Definitely a fuel delivery issue, just not sure which part could be bad still.

EDIT: just attempted the PRV test I saw here. If this is how it's supposed to function, then I still have a bad PRV. I watched the pressure slowly drain out from 450 > 380 over the course of a minute instead of slowly rise. Can someone back me up on this behavior before I drop $200 on a new PRV? Further, is that $200ish price real? I am seeing some Ebay folks selling for ~$90.

 

[Enki]

The engine has to be HOT for that test to be accurate. You need the heat in the fuel rail/injectors to heat up the fuel to cause expansion and increase pressure.

 

[_UsUrPeR_]

The engine has to be HOT for that test to be accurate. You need the heat in the fuel rail/injectors to heat up the fuel to cause expansion and increase pressure.

Oh, well that makes sense. I wasn't sure how the fuel pressure would continue to ruse while the engine was off.

Alright, well I've got a stock HPFP I am going to install. It's a different HPFP housing, so I'll not even be disassembling it. Going to see if the corksport was screwed up or I somehow messed up the rebuild perhaps.

Any other suggestions for repair parts, let me know. Did anything odd pop out in the lofs I uploaded?

Thanks!

 

[Enki]

Not much to check if you say the rail is reading 70 PSI. If it's going rich, it could be the fuel rail pressure sensor, but I've not seen them fail in that particular manner before. You don't smell fuel in the engine bay when it's having this issue, do you? That could be a leak, and if the leak is bad enough to drop pressure that much, it should be detectable with the naked eye.

 

[_UsUrPeR_]

Not much to check if you say the rail is reading 70 PSI. If it's going rich, it could be the fuel rail pressure sensor, but I've not seen them fail in that particular manner before. You don't smell fuel in the engine bay when it's having this issue, do you? That could be a leak, and if the leak is bad enough to drop pressure that much, it should be detectable with the naked eye.

Naw, no fuel smell. Further, if it were a leak, I don't think fuel pressure could vacillate between 1600 PSI and 70PSI. It would probably be at 70psi the whole time.

It read 1600psi whe cold, but fell to 70psi under WOT. Then it would come back to 400 -500 pai at idle again.

 

[Enki]

When you took apart and reassembled the HPFP internals, what did you lubricate it with? Also, was there any scoring or felt roughness of actuation (piston in collar specifically)?

 

[_UsUrPeR_]

First: I fixed it. I replaced the whole HPFP with an old stock one that I had, and seems to have done the trick.

I am unsure as to what is wrong with the corksport HPFP I tore apart and upgraded, but I am going to find out. datalog47.csv is idling up to temperature after installing the old stock HPFP. The idle seemed spotty and strange. It seemed to be searching up and down and sounded like it was missing at idle. I then pulled the MAF sensor plug (@188 seconds) and let it idle a while without it plugged in, and then plugged the MAF back in. In doing that, the MAF voltage seems to have significantly cleaned itself up, the idle straightened out. I played with the MAF wires while it was running, just to see if I could find a short, but nothing I was jiggling seemed to make any difference.

I did not notice anything strange when I disassembled the HPFP internals. You can see photos of the internal components in my previous posts. The first time I cleaned it out with brake cleaner and lubricated with 10-W30 engine oil. The second time I purchased naptha and Red Line SI-1 Fuel Cleaner.

In datalog49.csv, I start to drive it around, and experience none of the previous issues.

Any ideas about what could be going on with the upgraded HPFP, let me know. I'll pull it apart and check out what's going on with the upgraded HPFP. I am wondering if there's a problem with the MAF wiring. Still, it's behaving as I expect now.

Thanks for everyone's help!

 

[Enki]

Best guess is scoring causing it to grab, or just bad tolerances. I assume you could actuate the piston through the collar without any felt roughness or too much force required, correct?

 

[_UsUrPeR_]

That's correct. It seemed like a perfect fit. No hitching or binding in and out. After disassembly, there appears to be some wear on the piston in the photos, but that seems to be cosmetic, and may just be a reaction with lubrication or cleaning chemicals and the piston's anodized finish. I could not feel anything with my fingers or fingernails on the piston, and the interior of the bearing appears to be flawless.

I have sent a request to Corksport for their input. Hopefully they will be able to better diagnose this issue. Meanwhile, the vehicle is running with a stock HPFP, which I had from a previous engine. I have sent them a link to this thread.