Fuel Pump / Injector / Coil Pack Issues

[colin.ssc]

Hey guys, so I've been having some issues with my 07 V36 350GT Sedan for awhile now. The issues are on and off but now its present every day and it's starting to annoy the shit out of me.

1) At cold start / first drive for the day, when driven, the car would stutter (where RPM fluctuates and you can feel the car bucking). This issue is now present every time I drive if the car has been left to cool down. Initially I thought it was a vacuum issue but found no vacuum leaks.

There were talks about transmission issues and even engine oil issues in 350/370z forums but I am not sure if this is it.

2) Lately when I start the car, cranking it talking longer, some days it tries to crank, while rpm is v low it starts popping a few times. Stepping on the accelerator tends to get the crank going.

This lead me to think it's fuel pump, injector or coil packs not working properly.

I get no error codes whatsoever and am at my wits end. My mechanic said maybe try replacing the fuel pump first and go from there. OEM pumps looks to cost around $650 and up. Not sure if I'm looking at the right thing.

Would love some opinion re the issues but also opinions on if I should get OEM fuel pumps or look at after market ones?

[sonicii]

Might be a bit of a long shot, but have you been able to monitor the battery voltage from a cold start?

I had an issue on my wife's J31 Maxima a few years back where it would be hard to start sometimes and then splutter for the first 5sec or so after firing. After that it ran fine.

Turned out the battery voltage was low due to a lot of short trips (wife works about 3km from home), and it wouldn't run properly until the engine RPM was high enough to allow the alternator to supply the correct voltage. After taking the car for a long drive, it would be fine for a few weeks.

We just make sure it gets a reasonable drive on the weekends now and it hasn't been an issue since.

Also explains why the car eats batteries every 2 years or so.

Edited February 22, 2016 by sonicii

[colin.ssc]

Hmm, I did think of that, since initially the first issue did not happen all the time but I do about 350km to 400kms per week with half of that done on the weekend. I will check again on this though. Thanks for the suggestion....keep em coming!

For the first point in the OP, it only happens in first few min of driving.

Edited February 22, 2016 by colin.ssc

[Rufus007]

To stop the engine stuttering with a cold engine, try running Castrol Edge 0w40 oil. Worked 100% for me! (I had engine stuttering with both Castrol Edge 5w40 and Mobile 1 0w40 - the only other oils I have used in the vq35hr) The theory has something to do with oil density switching the VVT on just a bit to early ie during the 2-3 minute warm up mark. These engines aren't supposed to use VVT until xxx operating temperature, and are apparently fussy on oil choice. I personally also recommend OEM filters (get them from Nissan for the 350/370z) to ensure flow rates and relief valve pressures are correct.

Anyway there is a massive mamojam thread over here:

http://my350z.com/forum/maintenance-and-repair/307878-sputtering-during-warm-up-32.html

As for your slow engine cranking - I'd think battery first and starter motor second.

I'd like to hear what works out for you eventually!

Edited February 22, 2016 by Rufus007

[colin.ssc]

Is your stutter when driving or just during start up? My issue is mostly the driving for first few mins. But will try Castrol Edge. Currently using Motul 300v 5w30

[Rufus007]

Stuttering in my car happened while driving during the first few minutes of warm up only. Has not happened since I filled with edge 0w40 a few months ago.

Edited February 23, 2016 by Rufus007

[colin.ssc]

Thanks, will give that a try and battery! Will update as I go.

[KiwiRS4T]

Thanks, will give that a try and battery! Will update as I go.

Be sure to do one at a time so you know what fixed it.

And if you need a new pump forget about the OEM unit you can get a better one cheaper from Scotty:

• scotty nm35

[scotty nm35]

Could be the pump or fuel filter, but more likely the spark plugs, or just water in the IPDM, that's where I would start.

Faults like this can get expensive if a mechanic is involved, especially if he hasn't worked on VQ's much.

[colin.ssc]

Could be the pump or fuel filter, but more likely the spark plugs, or just water in the IPDM, that's where I would start.

Faults like this can get expensive if a mechanic is involved, especially if he hasn't worked on VQ's much.

How do we treat for water in IPDM? And can you PM me re fuel pumps or filters? Heard you make em?

[colin.ssc]

Obviously I wasn't thinking hard enough when you said IPDM. Don't worry about that lol

[Rufus007]

This comment is spot on - change one thing at a time. I'd still like to know what works for you in the end, mostly because I once had the same issue from your description (sorted now though).

<p>

Be sure to do one at a time so you know what fixed it.

And if you need a new pump forget about the OEM unit you can get a better one cheaper from Scotty:

• scotty nm35

[Rufus007]

Hey Colin? Does your engine stuttering present similar to this YouTube clip?

[colin.ssc]

That looks very mild. Mine is alot worse. 0w30 indeed helps, stuttering nearly gone but still a little. I guess maybe it is the VTC issue? Will do more testing over the months (when I find more time).

Ordered a fuel pump from Scotty, hopefully that solves the cranking issues.

[Rufus007]

Glad to hear the oil helped somewhat. In the 350z forum I linked, there is some mention that fitting revised CVT covers worked. Depends how much it bothers you I guess.

[colin.ssc]

When it gets bad, it's very very bad, like something is breaking, so yes I will look into it. I've read that thread before just never bothered and thought about it too much / didnt think that was the issue as the VTC's don't turn on til it's hot enough...who knows. Annoying AF!

[colin.ssc]

So I got the car serviced last Thursday. I picked the car up on Saturday and since then the car has been starting up fine. Mechanics only did an oil change. Very odd.

[Rufus007]

Awesome. Just for forum records, what oil did they use?

So I got the car serviced last Thursday. I picked the car up on Saturday and since then the car has been starting up fine. Mechanics only did an oil change. Very odd.

[colin.ssc]

Castrol Edge 0w30

Starting fine as in I had issues at cranking. On the stuttering issue - the stuttering is still there, very mild, quite delayed. I think (just my opinion) that the stuttering is happening on a certain temperature. Because of the 0w, this temp is achieved at a later time and because by that time I am already driving a longer distance without braking or letting off the throttle, I don't experience the stuttering.

Before this service the stuttering can only be felt if and when I accelerate / accelerate after letting to go of throttle (around the estate areas) etc if that makes any sense.

[Rufus007]

That must be the German castrol 0w30 is it? Think you can only get 0w40 retail in oz.