2004 350z touring 6mt 50k mi
APS Twin turbo kit
Kinetix Velocity Intake manifold

Uprev tune
AEM Wideband
AEM UEGO boost gauge


I bought this car last year with the APS kit already installed and judging by the vehicle condition it's been installed since day one. I put the kinetix intake on and other than a few sensor issues have had very little problems.

The other day it seemed sluggish while boosting 6-9psi and I noticed the wide band would go from 14.5 straight over to 17+ all red and I would detonate.. I've had and still have no check engine light, the last light I had was for the throttle body, I cleared it and have not had another in weeks.

I've read a ton of posts and haven't found much, I checked the aps 4bar fpr above the tank and pulled that apart, seemed to be fine, I can hear the pump fire when the key is on. not sure if anyone else has had this problem or knows what would cause a lean condition out of no where. car runs fine when not boosting except the prolonged cranking (4-6 seconds) when trying to start.

I get one good rich pull when the car is cold, it gets worse and with in minutes is leaning out completely.

Any ideas?

I Have colder #6 ngk iridium plugs that I will be changing to and am considering replacing the in tank 255 walbro and the 4 bar fpr.

help mee!

 

The aps fuel system is junk. Get rid of it and put a quality return fuel system with walbro in tank.

Without having the car in front of me it could be tons of things going wrong causing a lean condition. I would recommend not boosting it until you get it fixed. Also, boosting while the engine is cold is not a good idea at all.

 

I don't know about the aps fuel system thing... but if you wanna redo ur system which sounds like you have to from the issues ur having, go with the CJM stage2 return fuel system with the rail and twin hanger with X2 255lbs "only if you have any plans of building the engine in the future"... if not the go with the a stage 1 with a welbro 255lb or a DW340. I have ran both pump and I will tell you one thing DW is a better pump for high boost deal.. and btw I have the 255lb welbro with the housing setting around if you want it.

 

on another forum they were saying the aps kit comes with a walbro 255.. I was assuming thats what was already in the tank...??? and what is so inferior about the return system that would require replacing all of it? I have no problem doing it but I guess it bothers me to hear that it's "junk" when the cars ran flawlessly (at least as far as fuel is concerned) with this kit on it for 30k+ miles... I'm more interested in if something is failing or could be failing what I should check.. I pulled the 4bar fpr out and inspected it but I have no idea how to tell if its good other than being able to identify the diaphram is good and it doesn't look broken.

My thought process is that if it was a sensor I'd get a CEL which I haven't so that leaves my brain with a failing fuel pump or solenoid im unaware of or a bad fpr.. I'm just more used to complete failure of a part.. I don't half *** breakdowns..

I Have a stock DE so I will never be running more than wastegate boost through it. It's my daily driver but its pretty boring with out boost.

Either way if theres a ton of things that can cause a lean condition name a few and I'll get crackin.. There can't be that many parts that can be on the fritz and not throw a code.

 

you changed out the manifold and then had the issues? my guess is you messed up something on the install. My first guess would be the vacuum line feeding back to the fuel system.

At your levels the APS fuel system is fine.

 

I did the Kinetix manifold at the beginning of the summer and its been fine.. I thought it could have been that vaccum line to but my aem boost gauge T's off that inside the car and reads normal. Nothing else has been changed or modified recently.. I havent so much as pulled a piece of trim apart in weeks.. and just yesterday this started.

 

I'd say look at your tune, If you added a plenum, you should have got a tune then. Which APS kit did you get? There's 3: /03 /06 /09? Also check your Uprev, I bet you all your CEL's are disabled. What's the temp outside when you drove? Was it a big drop? I know my car runs better in the fall since it's colder but I have 2 tunes.. As far as the fuel pump I wouldn't worry about it unless your over 400 single should be fine.

 

How do you determine which kit is which? I bought the car with the kit installed, I then added the AEM gauges and kinetix manifold and other cosmetic mods.. I've had my wideband and kinetix manifold on for the entire summer and it's been hot here.. 80 - 100 deg.. The car runs noticeably slower as you would expect in the heat but my air/fuel ratios have always been fine.. This problem started a few days ago while the car was hot while I was running around town . Ambient air temp was around 80 deg. literally started it up at the grocery store, noticed it took a longer crank than normal to get it started then noticed that it was hesitating under boost. Looked over at my AEM and it was going lean under boost.

I would love to "check my tune" but I have no idea what that would involve. I feel like all the forums about tuning are asuming you know everything about osiris and uprev tuning. No one really bridges the gap from veteran tuner to noob tuner. GRD who tuned my car for the last owner in chicago is hours away and I don't understand how I would have a tuning issue when nothings changed in months. I drive the car everyday and the problem started with the same type of driving same temp same everything.

Would it be worth replacing the in take pump and the 4 bar fpr on top of the tank?

 

Seems like a fuel delivery issue at higher IPW's. Could be something as simple as the fuel sock clogged up. I'd at least start there and work your way forward.

 

Yea I think thats going to need to happen.. can the entire fuel sending unit be pulled through that access panel or does the tank need to come down?

 

Tank does not need to come down.

 

if you had a fuel pressure gauge, you'd know pretty quick if the pump was going out or not

 

Tested fuel pressure back by the sending unit yesterday. When the pump does its 3-4sec prime when the key is turned I get 10psi and it immediately falls down.. Once started I have 50psi.. as soon as it sees load under acceleration and not even boost it falls to 25-30psi.

I have a new 4 bar fpr coming to replace the one that came with the aps kit, a new Walbro 255 and I bought a digital fuel pressure gauge so I can monitor this in the car in the future. I was slightly baffled why all these forums say you need to buy the special fuel rail adapter to add a pressure gauge when there is soft supply lines right above the tank which are super easy to access and add a cheaper fitting there. I bought the stupid expensive one anyway but the entire thing seems foolish IMO.

 

hopefully that does it for u, i have the aps extreme fuel kit which is 2 walbro 255's and it has worked flawlessly, im assuming you have the basic with only one and changing the fp is pretty easy fyi

 

There are bigger fuel pumps than the 255 Walbro
If you going to change it out might as well go for bigger (Walbro 400)

 

The reason I say the FPR on that fuel system is crap is due to the fact that it is a non-return system and it cranks up fuel pressure way more than it needs. Most of those increase fuel pressure 5-7psi for every 1 psi of boost so it effectively forces more fuel through the injectors. This is the backwoods cheapo method of getting more fuel. The proper way to get more fuel is to run proper sized injectors with a return system. Running extreme fuel pressures in order to get enough fuel is only asking for something to fail. Obviously this is true because you had the FPR fail.

That's exactly why I removed the junk vortech FMU which raises fuel pressure so high and went to a proper fuel system.

 

Found my issue.
I did replace the FPR and bought a new and yes genuine Walbro 255 (which was only $70 anyway..) and when I pulled the sending unit out found a blown apart Fuel pump grommet. Only downside is you cannot buy the grommet separately. I found and ordered 2 for an EVO (OEM Evo Fuel Tank Grommet Part# MR431121) in the mean time I made my own which was a pain.. but its working. All I can say is I must have had a fuel issue for a lot longer than I thought. My car is so much faster than it was, it's responsive, crisp and a beast. The grommet must have been failing since I bought the car last year because it's truely a different machine. I wanted to post my find as so many others do not, which is ridiculous.


Ohh, the other photos are of the part I fashioned at work which my current "fix" is utilizing.. I used large injector O-rings a small piece of in tank fuel line and a carefully made aluminum adapter. down side is it moves the pump down a half inch and the bottom of the sending unit had to be slightly modified. but I can go back to the original set up if this Evo Grommet works that is in the mail.

http://s56.photobucket.com/albums/g1...pse262e04f.jpg

http://s56.photobucket.com/albums/g1...psf662e569.jpg

http://s56.photobucket.com/albums/g1...ps29f2d6bf.jpg

I also bought a Fuel pressure gauge with the fuel rail adapter... Not havin this issue again.