its not the reg, because wide open, most reg will only go down to mid/high 30s psi.

 

I would venture fuel pump or restriction in a line maybe

 

hmm. guess ill check with another gauge and have to check out the pump this weekend. but the pump sounds the same as it did before. how would i check if a pump was good? continuity?

 

i took off the vac line on the reg and got a 3 psi increase in fuel pressure. so str8dum was correct to assume the reg was good. ill check the fuel filter and im ordering the aeromotive 340 pump tonight. i need to upgrade from my 255 anyways.

 

Funny.. I'm having a similar issue, except mine isn't constant.

P0021 and P0300, which I'm betting the 21 is causing the 300.

It misfires at idle, then when it's warm it will every so often. At a low RPM cruise you can hear it putt, under boost nothing is wrong at all.

My vacuum is all over the place as well. Before operating temp its at like -1/-4 jumping around. Cruising, -20. After going into boost even a little and back to neutral the vac stays at -15. If I shut the car off and start it again, back to the -1/-4

Suppose my next step is looking into the IVT...?

 

Fixed it.
Tool apart the IVT's put em back together.. fixed... I dunno wtf lol

 

Probably the valve was getting sticky. It basically just slides in and out.

I changed my fuel pump today and nothing. Fuel pressure went up about 3 psi. Might have to look at the return sys or press reg.

 

here's some pics on switching out my 255 walbro and putting in the aeromotive 340.
One big note: the aeromotive had pos(+) and neg(-) markings on the top of the pump. they were reversed from the walbro. so i switched the wires while soldering on the new connector. BUT i could have just swapped the pump because i found out later that my car wouldnt start and the pump would turn. so i switched it back to how my 255 walbro connector was soldered and my car started right up.

 

also heard about fake sard regs? whats that about? well this is a pic on how my reg looks. i dont really want to mess with it. but if anyone can tell me it looks fake or the adjustment looks way off that would help. I pulled the vacuum line off and the fue press went up 4 psi. So i can assume its good, right?

 

just wondering, have you tried to put all the stock fuel stuff back from the injectors all the way back to the pump to see if there's something wrong with the fuel system? It would greatly narrow it down.

 

no i haven't. i actually turned the fuel reg in 3 whole turns and got the pressure to get up to 53-54 psi at idle. the "burping" noise has gone away but the ses light still flashes and i still have that damn p0300 code popping up.

 

Clear the code and drive the car 50mph+ for 5-10min shut off for 1 min then repeat process and see if the code comes back


Glad you seem to have the issue resolved and it was just bad fuel pressure

 

yeah i disconnected the battery last night because of the ecm might have stored the problem in its memory. im gonna try and start it tonight and see if it fixes it. i feel like im getting closer to getting my car running great again...

 

I have nothing to add as I'm a total noob but bravo and kudos are due to the 350z community for helping out over the long term. I've seen this thread up front and center since just about when I joined and I've read through all posts out of curiosity and I'm really just amazed at the commitment from the community. Op, I hope you start your car tomorrow and all is good. For good!

It will be a true victory for you for staying the course and working on following through with the many suggestions. And the followers / contributors of the thread... Amazing.

Again gentlemen- Truly awesome...

 

I agree. I am truly grateful for all the suggestions and replies. Im going to wait another day to start my car. Everytime I look up a part to replace due to this dtc I end up buying parts for a car thats not running right.

Anyways, my mishimoto radiator and thermostat came in today so ill be changing those out tonight. Plus my greddy oil pan is leaking so i have to drop that and reseal it. ConceptZperformance and Z1motorsports are awesome. I really want to get the akebono brake kit from czp but I have to get my baby running perfect again.

Back to the topic, I've heard it take about 48 hours for the "keep alive memory" capacitor to drain all its juice for the ecu. The ecu might have been trying to make my fuel system "rich" due to not having enough fuel pressure. Now that I do have enough fuel pressure it might be running "crazy rich" now because of the "keep alive memory" in the ecu. So that's why im going to wait abother day to start her up.

Thanks again everyone...

 

This is just a theory but I'm thinking my flywheel might be warped and throwing off my crank position sensor. Does that make any sense to anyone? That's the only thing I can think of. I checked everything on the motor compression, valves, and the engine harness. I still have to change out the intake valve timing control solenoid. If that doesn't do it I'm going to take off the tranny to check I everythings good down there. I get crazy clutch chatter and was going to put off changing the clutch and flywheel till I fixed this problem. Anyone think a messed up flywheel could cause the ecu to cause misfires?

 

Anyone concur?

 

Take your crank angle sensor out and look at the timing ring while someone cranks the car over.

 

What would I be looking for?

 

You are making sure its spinning straight and does not wobble.