Fuel Pressure a little low

Hey guys, I was wanting some advice on this issue before I start throwing more money and parts at the problem. Car is a 2006, completely stock other than an Accessport with the Cobb Stage 0 tune on it. TLDR version: Car threw code P0192, I put in new Fuel Rail Pressure Sensor, now it runs but won't go over 1456 PSI.

Last week I had the AP hooked up to monitor the health since I was planning on buying some HPFP internals, and intake, and a tune in the near future. For funsies I swapped over to the Cobb Stage 1 map, and when I was testing max boost in 3rd gear the car threw a check engine light, and I drove home and checked what the code was for. P0192, fuel pressure sensor low voltage. At this point the car would crank and idle but it was really rough, and the pressure reading on the AP was 0. I reflashed the Stage 0 map just in case it was a bad flash or something, but nada.

So I order a new fuel rail pressure sensor. I got a cheap one from Amazon first but it didn't work, then I ordered the GP Sorenson one I found in a link on another thread. Put it on, cleared the code, primed the system and then the car cranked just fine after a few seconds. I drove it around gingerly with my eyes on the fuel pressure, I set the AP to display the desired fuel pressure and the actual fuel pressure, and they were pretty much in sync.

After it warmed up and I was satisfied with the pressure I started giving it some boost, and here's where the problem lies. The car's actual pressure's max was 1456. Turbo seems fine, surprisingly I didn't get any knock retard. (Thank you super rich map?) The car actually feels just fine, although I'm not boosting due to fear over the fuel pressure. I drove it quite a bit, and it was the same, I'd cruise with the fuel pressure at 1300 psi, and when I hit the gas some the desired fuel pressure would go up to 1600 or something, but the actual would never go much above 1400. Before all this the car never had any trouble keeping it with plenty of fuel on pulls, and usually maxed out around 1700 something.

I found this thread when searching, and the OP seemed to have similar issues starting at post 42: https://www.mazdaspeeds.org/index.php?threads/fueling-issues-2012-ms3.9502/ From reading that thread it looks like his fix is to replace the whole fuel rail. It seems like that will probably be my next step, but I though I'd check first for opinions before I start throwing money at it. I really don't want to have to take everything apart to install a new fuel rail, although it would give me an excuse to finally pull the injectors and get them cleaned and install some injector seals.

 

.........did you try the things in the thread?....start there....
Diagnostics will the same, replace pressure release valve, clean hpfp and spill valve / replace the valve good time to install internals if you're doing them. Rays Mazda parts in Facebook sells some of ring kits. Maybe clan fuel rail if that doesn't work.

Edit also more info on pressure https://mazdaspeeds.org/index.php?threads/possible-fuel-pressure-problem.9308/

 

Well not yet, as other than the sensor I don't have spare parts laying around to test swapping HPFPs, PRVs, etc, and wanted to seek advice before spending hundreds on parts I may or may not need, especially since in that thread the parts swapping did nothing to help until he replaced the fuel rail. I was planning on getting one of the o-ring kits and rebuilding the HPFP anyway when I did the internals, so I could always start there.

 

Wow, it's really been 2 months, how time flies when your car is busted!

Just posting the solution here for any future people who have similar problems. Just like that thread I linked previously, the final solution was to replace the fuel rail. And yes, I did pretty much everything else I could possibly do to keep myself from removing the intake manifold, but in the end it's really not as bad as it seems once you do it. The fuel rail seems to be just a hollow hunk of metal, I couldn't detect any kind of blockages or anything from the old one, but I can't argue with the results that the new (used) one works perfectly.

While I was at it I cleaned up the intake manifold and throttle body, cleaned the intake valves (man, it really needed it) and installed a set of injectors that had been cleaned and flow tested with Corksport seals on them. I cleaned and rebuilt the HPFP with one of Rey's kits and Autotech internals. I put in a new PCV valve and plate gasket since it looks like I was leaking oil from there. I even replaced the pivot shaft seal and primary 02 sensor I've been putting off forever.

End result, car runs better than ever, fuel pressure is solid and even my max boost is a little bit higher. The engine even sounds a little different somehow, a lot smoother. I also now probably know more about how this engine is put together than even my Miata, which I've had for 15 years now.