Long and rough warm or hot restarts
 

Beginning of thread:
Yes, i know it's an old clunker but i like to rescue good cars and give them a second chance..
2007 G35 Sedan Base V36 VQ35HR 5AT.
No engine mods except air intake filters that use stock MAF tubes.

Here is the problem with it, when cold, starts up within 2 seconds and idles fine at 675-700. But when i take it for a few minute drive and the engine is at normal temps, i shut it off and few minutes later when i go to start it up to leave, it takes 4-5 seconds to start and sounds like it's out of fuel pressure.. Wait, don't shoot out the answers just yet.. NO CODES, yes, no stored or past error codes of any kind in any module.
Once the car starts, it does donuts and elevens just fine, shifts fine and goes like hell, it's just that embarrassing warm/hot restart that i can't seem to get rid of and it makes this car look worse than a 1976 ford pickup truck with 500k miles on it..

Things replaced so far:
-All 4 cam sensors with Hitachi CPS0032
-Crank sensor Hitachi CPS0220
-Replaced coolant temp sensor
-Replaced oil gallery gaskets and oil seals
-Cleaned T-Bodies and did ALL relearns
-Cleaned MAFs
-Replaced PCV hoses and valve
-Replaced spark plugs
-Replaced fuel pump assembly
-Replaced BCM (had few issues of it's own)
-Updated ECU to most recent software using NERS
-Replaced all fluids
-Replaced intake manifold gaskets
-Removed fuel rail and no dirt or obstruction inside it.

I've had many cars but never a PITA like this one that requires more pampering than a actual human baby.. I've connected Consult 3+ to it but not much help there, FSM is asking for too many wire probing and i don't have piggyback plugs for that.

Here is link to 1st video that shows me priming the fuel system twice before hot engine restart: Here is the 2nd video that shows the hot restart issue with engine off for about 30 seconds: Here is the 3rd video that shows me hot restarting the engine after 5 seconds and starts up fine: .

I am leaning towards fuel pressure bleeding issue but this system needs a special $50 adapter to tap into the fuel rail. I have swapped fuel pumps, OEM and aftermarket, same issue. I can hear the fuel pump prime and even the next day, there is still fuel pressure in the line. It's as if one or two fuel injectors were bleeding fuel inside the engine and wetting the spark plug(s). I've searched and searched and found few posts that begin with very similar issue but never finish with any resolution or fix. I'm sure someone on here has had this type of issue or heard of with the G35 with VQ35HR engine and found a solution. I don't want to keep on replacing parts just to find out they don't fix anything.

I have a xTool D7 scan tool and it shows me the sensors and i can also datalog 8 sensors at one time but they all seems to work together just fine. I dont have specs for any sensors for this car, like what the cam degrees should be at idle and at 2000k rpms.. I've looked in the FSM but no luck. I would know what value to look for if i had another G35 with a VQ35HR next to me to compare but i don't. I've looked into UpRev but for $550? NDS3 only supports 350Z with VQ35HR..
Any help would be appreciated, it's a nice clunker to drive when you have a 2" drop springs and 370Z Nismo shocks along with 370Z rims and new brakes and VLSD and few other things..

https://cimg8.ibsrv.net/gimg/g35driv...a8415889ec.jpg
Yes, that's a dry carbon fiber wrap on my hood, roof and trunk to cover the 0.5mm of Nissan quality factory paint!

Will it start properly if you prime the fuel pump (key on engine off), then key off, then crank? If fuel pressure has bled off, priming once before cranking should build the pressure and result in normal crank/start if that's the case. I had a long crank problem in my 06 with VQ35DE that's well documented here due to bad fuel pump check valve. But usually took a long time to decay like overnight. Not warm start long crank. I also have a Murano with a VQ35DE and that forum sees warm start problems occasionally. There was a TSB for that car that required some kind of fuel map reprogramming. The way owners could confirm if the warm start fuel map was the problem was to disconnect the engine coolant temp sensor when warm. If the car starts normally if you disconnect the ECT sensor, then that pointed you to the TSB and fuel map issue. I know it's a different car but similar engine produced by similar engineers that might make similar mistake/problems. A couple of easy and free things to try anyway..... maybe it will move the ball forward to figuring out your problem. Good luck.

edit - sorry didn't watch the videos and see that you did the prime thing and it works. seems like fuel pressure then, no?

Here is the first issue:

I will swap out fuel modules and retest the fuel pressure.

Here is a video after swapping fuel pump modules, it holds pressure better but still promes to only 30psi. I went to AutoZone and rented a fuel tester kit to compare gauges and to make sure mine is true.

Fuel pressure test after module swap, .

def keep us posted. i hate threads with no resolution. mine is doing something similar on a hot restart, like it's struggling to start but eventually does (just like the beginning of your third vid). doesn't really have a long crank issue like in your 2nd vid. i'm thinking mine is the starter, since it only happens on hot restarts after letting her sit for a few (starter heat soak).
i did have an old G35 that had long crank times and the starter eventually gave up, but this seems to be something else in your case. my old thread: https://g35driver.com/forums/g35-sed...ank-times.html

Here is another fuel pressure test using a different gauge from AutoZone and it shows the proper 50psi on prime. My gauge is obviously bad and this is another example of how a diagnosis can go wrong and become a headless chicken..

.

Here are 2 photos of the fuel pressure gauge holding pressure, 10 minutes in between photos on cold engine.

https://cimg7.ibsrv.net/gimg/g35driv...f74651e041.jpg
Fuel pressure test at 2:20pm
https://cimg9.ibsrv.net/gimg/g35driv...bc637c5e84.jpg
Fuel pressure test at 2:30pm.

Now, I will remove my kustom fuel pressure adapter and go for a drive.

Here is the final hot restart video


As you can see, I waited 30 seconds before hot restart and it took some time to start up. Then I turned it off and waited 5 seconds to restart and that's how it should always restart.. My 02 Maxima 6MT & 05 Dodge Caravan with 310k on it start right up within 1-2 seconds, hot or cold.

any updates on your situation?

I just received the obd2 plug for NDS3 to start data logging but the adapter came without Windows 7 drivers so I'm waiting for them right now, I'll post my findings on this because it's not the way it should start.. I've had dozens of cars and none of them took so long to start except one old carbureted Chrysler car..

i hear ya. def keep us posted. you seem like the type that will figure this one out!

Well, no change in start ups, still about 3-4 seconds to start, but, takes less than a second to re-start if turned off for less than 10 seconds. Damn, this car is really something.. I have checked all 6 coils packs for resistance and to see if they all have the power transistors in them and this is the result:

https://cimg4.ibsrv.net/gimg/g35driv...16acf5ba1b.jpg


Pin#1 reading is between Pin#1 & Pin#2.
Pin#2 reading is between Pin#1 & Pin#3.
Pin#3 reading is between Pin#2 & Pin#3.

Pin#1.................Pin#2............Pin#3
1. 2.4K ohm......5.9M ohm......5.9M ohm
2. 2.8K ohm......5.9M ohm......5.9M ohm
3. 2.8K ohm......5.9M ohm......5.9M ohm
4. 2.6K ohm......6.0M ohm......6.0M ohm
5. 1.1K ohm......OPEN............OPEN
6. 2.6K ohm......5.6M ohm......5.6M ohm

Yes, #5 looks odd and doesn't match the rest, it also didn't have the power transistor in it, just spring and coil. I thought that this is it! But no. New Hitachi coil came, has the power transistor and measures same as #6 coil and same ****. Same long crank times 3-4 seconds hot or cold, but it takes half a second to re-start when turned off for less than 10 seconds.
I'm starting to suspect the NATS going nutz and somehow causing the start delay because everything else is working withing it's parameters.

Here is the video:

Just in case someone might be wondering, the car runs like bat out of hell, does 11s, chirps on 1-2 shift and runs strong, just the damn long start up time is what I can't figure out. Maybe it's this damned 2007 defect or a few off G35s..

it sucks troubleshooting something like this when you don't have much to go off, and everything that's required for a successful start is working as it should (fuel, air, spark, and timing). mine ('07 sedan) has a similar issue on hot restarts after the car had set for over 20-30 minutes, where it cranks quite a bit and finally catches. again, i'm thinking mine is related to a starter that's nearing the end of its life (cold ok and heat-soaked when car sits a while). i wouldn't lose sleep over yours but do keep us posted if you ever figure this out.

Turn on the ignition and wait about 20 seconds to see if the Service Engine Soon light starts flashing. If it does, count the number of the slow flashes from solid to solid and then replace that ignition coil. I've read on Nico forum about one guy saying that this SES light flash is related to ignition coils on Ignition On Engine Off.

Crazy as it sounds, I did have a 4 slow blink of the SES light and started up my car when above 180 degrees and it actually had a misfire! But guess what, no codes in the ECU or anything out of the ordinary for this damn car, but I knew it was missing because I ran a cylinder balance test and #4 was the bad one. When you scroll up, you can see that I tested the coils but when they were cold and that #4 was a Hanshin coil from decades ago before Hitachi took over so you might be having ignition coil issue and the best way to diag them is to heat up the engine, put on OveGloves and pull them out and test them to see which one has low resistance or no resistance when hot.

interesting. i've replaced all of the coils a few years ago with oem ones (hitachi). did you replace yours and your issue is now resolved?

P.s. I've recently replaced my valve covers and #1 cyl was full of oil. i thought bingo - replaced that spark plug and the coil, just in case, and it appeared to have been ok for a few days, but then was back to "normal". i'll give that check engine light a go today, hopefully.

The valve cover o rings can be replaced using Honda Civic ones, I saw a uTube video few months back. Once you have oil down the plug tube, you'll always get it refilled until you reseal it. Mine are good, the misfire went away but the long start up time is still there along with the light throttle surge at light acceleration. I'm waiting for a electronic fuel gauge to come in so I can test the fuel pressure under load. I bought the 11mm fuel adapter from Walmart. S&G tool aid 58625.