Hey Guys,

To start with here is my car:
www.vq240z.com


Ive been trying to figure out a problem with my vq for a while now and I really need some help figuring it out. Hoping some of you guys might have run into the issue. Ill try and be as thorough as I can describing what is happening.

Background:
The car ran great when I first completed the swap for about 200 miles. It could be a coincidence, but this all started when I tried to start the car when the battery voltage was low and it went into throttle body fail safe. Once I got the codes cleared and charged the battery the car started and ran great however when I took it for a drive it would die when I came to a stop...

When It happens and what it does:
- The car starts up and idles smooth when cold with a idle of a little over 1,000 rpm.
- If I let the car warm up in the driveway 50% of the time after it warms up it will all of a sudden start to sputter and after coughing a few times and trying to save itself it stalls out.
- Once its warm if I rev it up over 3K or so and then take my foot off completely it will drop past 600 rpm and stall out. If I pat the throttle a bit right before it dies it will recover and idle great (about 800rpm).
- If I take the car for a drive it runs and drives great, however when I come to a stop or coast with the clutch in it stalls.
-Whenever I restart the car 80% of the time it starts up and idles fine, the other times it coughs and sputters unless I give it throttle.
- Every once in a while Ill take the car for a drive and it works PERFECT no hint of the problem at all

What I have done:
- Replaced the battery, which has since held a charge great.
- Ran an ODBII code check. Nothing shows up pertinent to the issue. It throws plenty of codes but all related to things that I have unhooked, such as the a/c and power steering, chassis CAN line etc.
- Tried to preform "idle air relearn" manually by pedal input several times. Cant confirm if it worked due to no check engine light.
-Tried adjusting the fuel pressure: It was originally at 41psi which I changed to the factory 51 psi. Car ran really rich and problem was not affected so I lowered the fuel pressure to around 37. I have modified the fuel rails for a return system so my buddy recommended that I needed to only run 35-40. No change in problem.
- Replaced the MAF with a good known working unit from my personal 350z. Didnt make any difference.
- Watched fuel pressure when the car stalls as it is sitting in my driveway. It stays ROCK SOLID.
- The TB , MAF, Intake, engine inside of the intake tract is clean as a whistle...motor has 500 or 600 miles on it total.

Thing I am going to try:
- Swap out the throttle body for a known good unit
- Preform Idle air Relearn using a Nissan Consult.

I am kinda frustrated with the issue out of my expertise with this motor. I have talked with a reputable 350z shop that has experience with modified vq's and ems, and they had never had the issue or any advice. I was told they had no issues with a factory setup unless it threw a code. I have also talked with my buddy who is a nissan master tech about the issue as well and he has no advice to offer either. Really hoping somebody here can help!!!

Thanks for taking the time to read this and offer any advice!!!

 

dont know about the answere to that question but more pics of the car!

 

I had a member on Hybridz suggest changing the throttle body out, he is a tech and said a 350z came in with the same issues and no codes and that fixed it. So that is going to be my first thing to try. I had a 350z as a DD so I know eveything works on it lol, Ill start part whoring next time I work on the car.


liven z life- There are pictures and videos on my website which I posted above and is in my sig.

 

Do you have diffrent injectors? When the drivers for the stock injectors drive larger injectors some people run into stalling. My Z did when I went up in CC's. It did it with the greddy EU but the UTEC hasnt experienced any of those issues.

also try the throttle position relearn the voltages may be out of wack since the battery dropped out.

 

Everything is factory as far as the injectors and ECU. Just custom fuel supply for when I go FI. I have tried the idle air relearn procedure several times, however like I mentioned I have no MIL so I cant tell if it worked...does nothing for the idle situation. I gotta get up with somebody that has a consult to try it with the computer.

My buddy has access to one so hopefully I can get up with him, or else see if the dealership will do it for me, I sure as hell am not letting it leave my sight at a dealership though lol.

Thanks for hte help so far guys.

 

it definately sounds like it needs an idle air relearn done. are you in mooresville, in?

 

Nope I am in North Carolina.

I was under the impression it would have a rougher idle all the time and not idle well period if it needed the idle air relearn. For those that have had to do the relaearn what were your symtoms? When I swapped the intake on my DD 350z I just has a bit of an erroneous idle and the relearn fixed that but it never cut off.

I certainly hope that is all it is though...just need to get up with a consult argh!!

 

no, the car would usually idle high, and die after revving/start up.

 

I had the exact same symptoms ie. normal idel, idel drop out after reving fast, engine stall when clutch pushed in comming into a redlight (3k rpm +clutch in = stall). I was running into SUPER rich conditions with the EU and a technosquare reflash until I got the UTEC installed and tuned up.

It seems to be either the TPS as I mentioned before or a bad tune on the ECU for the injector size.

 

My buddy's 06 did the same thing when we started it up to check for leaks after the plenum and popcharger install until we did the relearn procedure. I would def. try it with the consult as others have said.

 

I was going to say maybe it's your tune but you're running on a stock ecu. I had the same problem when I was NA and had a unichip. I then switched to utec and the problem was gone. There is a good possibility that you have a bad throttle body. I would recheck for air leaks withing your intake. Check couplers and vacum lines. Make sure the PCV hose going into the bottom of your intake pipe is secure. You have a nice ride; I enjoyed your videos. Hope you get it all worked out.

 

Sweet, you guys have got my hopes up. I wont be able to work on the car until this weekend or possible the next but first thing I'm gonna do is find a consult.

I also need to get UTEC for this thing anyway I think a tune would definitely help the motor out with the exhaust and lack of any accessories except the alt. Plus she will be FI in the future as well. Money is just short right now...need to ***** out some parts.

What fuel pressure are you guys running with returns?

05Z33 - Thanks for taking the time to look at my site, glad you liked it!

 

on my 3.5 swap on my maxima...im only running 34~35 psi in return set up....I'm using the same spec as my 3.0 since the stock fpr is set to that. not too sure about the Z....=/

 

Aeromotive 1:1 rising rate FPR I'm pushing about 51psi on the top end of the pressure range. To tune effectively you need at least an adjustable pressure regulator. Idealy you need higher rates to keep up with larger injectors but dont put too much pressure behind them. Definately return kits are good. Im runing the AAM returns. Changed out all the O-rigs with higher quality ones. Also dropped a walbro 255LPH pump in the tank.

http://www.maperformance.com/aeromot...l-kit-dsm.html

 

ahh rising rate fpr nice. im just using a sard fpr and just set it to stock settings since i did not do a full 3.5 swap...used 3.0 timing so i can use my stock ecu with a emanage ultimate for tuning.

hmm...i ll def look into that when I do some work on the Z. thanks

 

Cool deal.

I am running a walboro 255 inline at the tank with -8AN feed and return with dual -6AN branching to each rail. I have the same Aeromotive FPR as well. Im NA right now so it doesnt really matter at the moment about it being RR. I have it set at 37psi at idle...

I actually just modified the stock rails for my system and so far so good, its nice and clean and should provide all the flow Ill ever need (500hp goal eventually) I would assume this would work for yall as well on in the 350'z just need to run a return line. I cant believe the prices for the return kits for the 350z

Here what I did:
http://www.vq240z.com-a.googlepages.com/fuelsystem

 

did this ever get figured out? I'm having the same problem! I just had my car in the shop for about 3 weeks getting the rear bumper and trunk repaired after a slight collision. Thanks.

If you have any info please PM me or find my thread on g35driver.

here's my thread on driver: http://g35driver.com/forums/engine-d...d-problem.html