limited/fixed HPFP pressure, misfire, drop in power, and inability to reach high revs smoothly

I've come here as a last resort. Heartbroken over months of trial and error.

Recently had the engine replaced, and had put in an Autotech HPFP. She has an HPS CAI and a HKS BOV... I know, it's horrible for the engine, but it came with it when I bought it, and I spent all my resources in maintenance. When it was ready, it threw a "running lean at idle" code. After bringing a Mazda electrics specialist in to diagnose and replace the cold soldered fuel fuse, the code was fixed. I ran into some issues with the car not hitting boost targets, which made me think that there was a vacuum/boost leak, but that was fixed after I had her ECU tuned properly with Stratefied.

The current issue is that there is a SIGNIFICANT drop in power, even with the 16.59psi the turbo is spooling. There's basically no torque steer, and she misfires past 4,000rpm. The misfires were less present after the tune, but they're still there. On my AP, she idles at 400-500. Once a blue moon, after not being driven for a day or two, and brought back after a drive, she needs to be throttle played to start after a few hours leaving her in an ever so slightly inclined driveway.

The max HPFP Actual Pressure she hits is precisely 1669psi each time, and thats at 20% throttle when she hits it, continuing at that psi all the way to 100%. She rapidly jumps from 400-500psi to 1200-1400psi and finishes off at 1669psi in less than a second once I put my foot down. She actually drives smoother and faster when I'm at 40-50% throttle than when I WOT, which leads to backfires, and throws a CEL. I haven't attempted to see if she still throws the code after the tune, but I know she still can't climb the revs properly like she should. She goes up well up to 4000, and if she doesn't backfire, she slows down massively during rev climbing, almost stops at 5,500, and throws a P0300 code, along a IC U2064, which is a non-specific code the ECU is unable to find.

The only thing that makes sense to me is that shes not getting enough fuel and is somehow electronically limited to 1669psi. I've read this https://corksport-com.cdn.ampproject.org/v/s/corksport.com/blog/hpfp-troubleshooting/amp/?usqp=mq331AQFKAGwASA=&amp_js_v=0.1#aoh=15961423605087&referrer=https://www.google.com&amp_tf=From %1$s

It's a troubleshooting guide for HPFPs:

"If you are having an odd intermittent issue such as fuel pressure fluctuations that bounce around from 400 to 1,500, or something of that nature, then expect the following:
◦ A sticking spill valve that is not allowing the correct amount of fuel into the chamber. (This is especially true on high-mileage cars and on cars where guys run lots of ethanol.)
◦ A stuck-open pressure relief valve.
◦ A bad HPFP housing check valve exit.
◦ Damage to the HPFP internals themselves.
◦ A broken seal screw O-ring or an improperly torqued seal screw."

I don't understand how the mechanical fuel pump can always hit 1669psi perfectly, but I am having my old fuel pump with the OEM HPFP from the previous engine put back in, because I know that one works for sure, and it would eliminate any pretenses towards the mechanic messing up the Autotech HPFP when he first installed it. The guys at Stratefied were apprehensive towards giving me a specific diagnosis, but the overall conclusion was that it might be the fuel rail sensor.

Either way, she's gonna be done on Monday, and will be given a new O-Ring as well, but compared to how things are going, I really don't think that will fix the problem. I've done as much research as I can but I can't find anyone with my exact problem. From what it could be, it might be the fuel pump itself which is getting swapped, the fuel rail sensor, or even a failed PCM/ECU. Hard to love her right now, it's been months since I've had her back to normal. Y'all are my last hope if the fuel pump swap doesn't work.

 

Some logs would be good. Compression test is also advisable too.

 

I hope these logs are enough. Should I ask the shop if they have their own kit or buy my own like this one:

 

Parts places rent em out. I really am not recommending cheap Chinese testers. They may not be accurate.

 

Additionally, there's something I forgot to mention. Ever since the engine swap, on a cold start, there is a loud rattle/clanking noise when the car starts. From what I could find out, it might be the VVT actuator, solenoid, or chain. I have an engine warranty to the shop that swapped it so I'm thinking of getting done there. Could a faulty VVT cause such problems? I know it can be fatal.

 

Bro. That's not good. Take it in for inspection. That's vvt or chain or both.

 

hey did you ever find the issue with this? i have a similar situation on my gen2 swapped gen1

 

Okay I'll take it to the shop on Monday after I pick it back up from Mazda.

 

No not yet... if swapping out the fuel pump doesn't do anything then I'm going in to get the VVT checked and after that I have no idea... maybe the fuel sensor but highly unlikely.

 

any luck?

 

Hey guys, so swapping out the fuel pump and putting a new o-ring in fixed it! It still has the VVT rattle obviously so I have to take it in for that. The bad part is that I have a $500 Autotech fuel pump sitting around and that my AP still reads 1669psi for HPFP, so that might be a faulty fuel rail sensor reading. The mechanics must've fucked the process up when putting the Autotech pump in originally. Goes to show, you want something done right, do it yourself, if you're not a lazy idiot like I was.

 

What pump.did u replace, the Intank pump, I'm having a similar issue with my gen 2. Also what o ring did u replace

 

Wow , I know this is an old post however I've been having the same issue but I didn't do an engine swap, just parts. I think my issue is freaktune because my speed ran perfectly, I replaced the turbo with a corksport CST6, then had to do, fuel pump,battery box new fmic piping ,downpipe... I installed the freaktune and it's doing all the same as you described in the first post... I can't get Justin to email me back ... honestly stuck.

 

Start a new thread and describe everything in detail. Post a log.

 

Have you had any luck figuring out the issue ?

 

I’ve been having the exact same issue. Cannot figure out what it is and I’m not too confident in troubleshooting that kind of stuff. I replaced my spark plugs and tried cleaning Maf sensor and using a fuel injector cleaner in my gas and still nothing… anything else I should try

 

I’m having a similar issue as well! Except I’m not getting any codes just hpfp reading on my ap not going above 16xx psi. Current mods of mine are extensive but basic break down is full bolt on, bnrs4, built bottom end, refreshed and inspected head ( all Oem ).

didn’t have this issue before when I was k04 and stock block. My hpfp internals are a bit old as I’ve had them with the car for 5+ Years. I did the corksport hpfp rebuild kit, which is where I’m thinking something went wrong.
I was thinking to take my autotechs and put them into another hpfp housing with a different bucket and spill valve to see if that helps fix the issue will keep in touch with more updates!

I will leave my Facebook and Instagram names below to help keep better In touch with those who are having similar problems!!
Facebook: Bryan crawley
Instagram: ms3crawley

 

Check maf sensor. I had same problem but running rich. Problem was one of the wires to maf sensor was loose. I would shake the wires and hear the idle change.

 

I had this issue, would only read 1600 and some psi. Come to find out the fuel pressure sensor in my car was a 90bar and wasn't capable of reading above that. Bought a 140bar at fixed it.