VQ35DE Question.

[GR_CoB]

Hope you're having a good day there friend.
Got a 2008 Infiniti M35 with the VQ35DE engine (according to tab in the engine bay) with about 185k miles. It runs beautifully, but has a small issue. Every 5-7 starts it experiences a long-cranking situation. Usually it cranks right up, but on that 5th-7th start it cranks for good 7 seconds before starting, and that is a bit alarming...
Quick search on forums lead to replacement of both camshaft sensors and crankshaft sensors with new OEM ones, as the ones on the engine seemed to be the factory installed ones from 2008. But new sensors didn't change a thing.
I guess next step is to look into the fueling side of things, but don't really have thousands of dollars laying around to throw parts at it.
So I was wondering if any of Infiniti owners here experienced a similar issue and found a fix for it.

Thank you in advance, and appreciate any pointers!

 

[bbhero]

Being straight forward... Sounds only like a battery or potentially a starter issue...

If it really was a camshaft or crankshaft sensor I'd bet it would not run well at all.... And because it runs well once started. . I'd bet the fuel delivery system is quite likely doing just fine too. If it ran like junk after starting... Then I'd think that could be a problem. But being that it runs very good... I don't believe that is your issue either.

If it runs just fine... Aka no misfires etc etc...

Then I'm thinking it's something possibly simple.

How old is the battery in the car ??

Starter original or replaced ??

In summer time... I have seen a car act very similar to yours... And it was a battery. My lady's Sunfire did that. Reason is in the summer it takes less amps needed to start a vehicle. Thus a shaky battery can start a vehicle most if the time because only 150-200 amps are really needed if it is 75 degrees plus outside. Where as in the winter where your vehicle needs more actual amps to actually start the vehicle... It will just not do it at all.

My car with the same exact motor.... Has 316,000+ miles on it. Orginal starter and alternator on it still thank goodness.

 

[MolaKule]

Have the spark pugs been replaced?

Purchase or Borrow an OBDII scanner and see if there are any codes that have been stored. Advance Auto, O'Reiley's and other AP stores may do this for free.

 

[bbhero]

I could well be wrong here in regards to this vehicle circumstance...


However if the vehicle "runs beautifully" after these starting problems per the op...

In my way of thinking of things is when does the event or events happen?

Can the event be isolated to a particular time or set of conditions?

Is it happening after the vehicle is running for awhile?

Or does it not happen at all after the vehicle is running?

If it were a camshaft or crankshaft sensor issue... The car would not run well at all after start up. Those sensors are not just going to be bad at start up. Those sensors will not operate correctly throughout the while time the vehicle is running. And It would be very likely throwing OBD II codes too for that problem has well.

On my decision tree... Then it is not likely a spark plug issue because it would not run well at all while running. Bad plugs do not just happen at start up... It will continually happen has the vehicle is running. It would idle roughly and would miss under load. Per the op the car runs beautifully. If it is missing bad enough... A OBD II code would be going off all the time. I know that from my own experience. Anytime the OBD senses too many misfires... It will set a code off. And that light stays on unless it is turned off with a code scanner that can do that.

If the car ran poorly after start up then yeah bad spark plugs would maybe be a possibility. Or if it ran poorly after start up it could well be a fuel delivery system problem... But if it "runs beautifully" after this start up problem... Leads me to think it is something isolated to that only.

If it was a fuel delivery issue.... Again in my decision tree it would happen all the time... Not just when starting the vehicle every 5th or 6th or 7th time. If the fuel pump is bad... It will be bad often while the car is driven. If fuel injectors are fouled up and bad... Then the car would run poorly while under constant operating conditions. Not happen every 5th or 6th or 7th time starting up the vehicle.

If this issue is clearly limited to starting up only... Which sounds like it is the case here with the provided background information thus far...

It would seem to be isolated to a summer time battery failure or a starter on it's way out. My lady's Sunfire did the same exact thing with a battery that was going bad during the summer time.

 

[CharBaby]

I had a similar issue with my previous 2004 Altima(although it was the 2.5L 4 cyl). And it turned out to be a split hose on the fuel pump inside the tank. Only happened in the summer heat...IDKY!

 

[GR_CoB]

- OBD2 checked out, my app shows no codes stored in the ECU. I manually unplugged one of the cam sensors and it immediately gave a code for that cam sensor. Plugged it back in, all back to normal, no CEL.
- If G35 forums are to be trusted - this engine uses the crankshaft position sensor to start, and camshaft position sensors to keep running. Also for some other owners of such engine the ECU was giving false CEL codes for Bank 1 Camshaft sensor, when in reality the crankshaft sensor was the faulty one. I have sold at least 2-3 sets of crank/cam sensors for Infiniti per week back in my AutoZone days in 2014ish. So these engines do go through these sensors quite often compared to other vehicles.
- Alternator gives out healthy 13.8V at idle.
- I haven't checked the battery yet, so appreciate pointing that out. Such a simple thing that I completely overlooked it. BUT the reason why I haven't considered it - is because if after a long-cranking event I shut the car off and try to start it again - it fires right up for next 5ish times. I never seen a drained or dead (ish) battery come back to life and pump out good cranking amps for a few more starts.
- It does have push-to-start button and I wonder if that may be related? But other owners say that it either works or it doesn't, haven't found anyone who had an intermittent issue with that button or the functions behind it.
- The reason I thought about fuel is maybe there is some kind of pressure loss going on? Although it doesn't make sense why it would be intermittent like that if it was fuel related...
-The 5th start deal does not seem to be affected by time of the day, how long the car has been sitting, or the engine temps. Almost makes me wonder if it's ECU related?...

 

[GR_CoB]

Also the vehicle is new-to-me. Previous owner said Spark Plugs were replaced last year, but I may just replace them for peace of mind. I do agree that if spark plugs or the ignition coil was the issue - it wouldn't be intermittent like that, or would give more issues when engine is running, such as a miss or skip at low/high RPMS, etc. It doesn't.
Starter seems to be original. Will investigate.

 

[JTK]

Can you hear the fuel pump buzzing prior to the long crank scenario?

No codes, no issues while she's running and no proper diagnosis means you're just changing random parts.

Can you repeat the issue if you just keep start/stop/starting it?

I'd watch for fuel pressure when it happens.

 

[slacktide_bitog]

Is that 5-7th start when the engine is hot?

 

[rekit]

Wife had a 07 Corolla that did that.....never figured it out. She swore rolling down the windows usually made it start. I didn't buy that but she did! It never left us stranded-ever!

 

[zrxkawboy]

I would try to see if fuel pressure is bleeding off before those extended cranks are happening.

 

[bbhero]

I had a similar issue with my previous 2004 Altima(although it was the 2.5L 4 cyl). And it turned out to be a split hose on the fuel pump inside the tank. Only happened in the summer heat...IDKY!

That is strange and interesting...

I just wonder if it would have a hard time starting... Then would the car not run right after starting... Aka like starving for fuel... Lack of power under throttle.

I just had a vacuum leak in my car. I noticed at Rte 5 intersection my car was idking at 1,100 rpm... Which is definitely not typical. It usually is 700. Then I noticed the car would lay over and not have power under acceleration. I figured it was a vacuum leak. I knew that it was well off normal operation standard. Interesting enough I had noticed my fuel economy had been off the previous 6+ months... Only around 27.7 to 28.2. Verses 29.1 to 29.6. I had the rubber part with bellows changed out- it had a big crack in it. And sure enough car ran like it should... Motor ran hard and did not lay down under throttle... And fuel economy has been back to normal baseline 29.1 to 29.6. My problem here was not isolated to start up... It happened after the car was running.

I have had bad spark plugs... Trust me.... It caused my whooptified Dodge Neon with only 32,000 miles to run BAD... Like it would run but it was running so bad I had to park it. Thought about it.... Figured it was the plugs were bad. Replaced the 4 spark plugs... Viola.... Car ran perfect. My Ford Fusion did the same thing but no where near as early aka 102,000 miles and it only missed badly 5-6 times. Replaced those plugs... Car ran perfect. In my experience.... Bad plugs don't just happen at start up. They happen while the vehicle is running.

Again I could well be wrong... I have heard of fuel line/pump issues in the VQs. Of note... In one case people typically were purchasing bad gasoline routinely. I would lean towards it being a summer time battery failure. My lady's Sunfire acted just like what the op has said to a T.

 

[Hall]

FWIW, on Nissan / Infiniti focused forums, it seems like the camshaft and/or crankshaft sensors are blamed for everything !

When I read your post, my first thought was starter....

 

[CharBaby]

But the starter was turning over the engine according to the OP.
It was experiencing a LONG CRANK(7 seconds) which means the starter if fine.

I too have had a bad Crank Position Sensor(a completely different time/scenario & issue) but, I was getting a CEL & code. The OP is not.

***When I would get this long CRANK TIME(mine was also when it was HOT outside),
I'd stop cranking the engine and instead, I would cycle the key/fuel pump(3X for good measure--not knowing if 2X would be enough) and the engine would start every time. This can also be done with push button start but it's more of a pain.

 

[Kokopelli34179]

***When I would get this long CRANK TIME(mine was also when it was HOT outside)

I have this long crank time as well on the MR20DE engine. No CEL. Happens when very hot out. Thinking it could be crank sensor, but with no CEL or pending codes, I'm not sure. I did run a bottle of Techron, (I mean it can't hurt to do so, right?), and so far, it has been much better. No long crank in while, so maybe it's a fuel system thing, or maybe not. Only time will tell.

 

[oilstudent24]

Had a late 90s f150 that would crank a bit to start, but would run fine once started. Hot or cold didn’t make a difference. I borrowed a fuel pump test gauge from the auto parts store and had low pressure. Some auto parts will rent the gauges for free. You just put down a refundable deposit.

 

[CharBaby]

I have this long crank time as well on the MR20DE engine. No CEL. Happens when very hot out. Thinking it could be crank sensor, but with no CEL or pending codes, I'm not sure. I did run a bottle of Techron, (I mean it can't hurt to do so, right?), and so far, it has been much better. No long crank in while, so maybe it's a fuel system thing, or maybe not. Only time will tell.

I replaced my Crank Sensor long before I had this(non related) long crank time.

 

[Lapham3]

My wife has a 2005 350z summer driver and there were several intermittent long cranks and eventually a code for the crank sensor. I sourced an OE sensor and with an easy replacement, all was well again.

 

[GR_CoB]

Thanks for all suggestions so far, keep them coming. Here are some observations and answers to some questions.
- The starter is good. It spins with the same speed always, without any "hiccups" or slow-downs, whether it is the normal or the longer cranking start.
- The battery has been tested and it is good, happens to be less than a year old.
- The fuel pump can be heard priming on every start.
- The long-cranking situation (once in every 5-7 starts) is there if the driver gets in, foot on the brake, and pushes start button. BUT if the driver gets in, pushes the start button (lights & accessory mode ON), then gets foot on the brake pedal and starts the engine - then the long cranking situation is completely gone. This points me towards the thought of fuel pressure bleeding off somehow in time for that 5th-7th start...

Quick summary:
Press brake + push "start" = long cranking every 5-7 starts.
Push "start" + press brake pedal + push "start" again = no long-cranking situations.

 

[cronk]

My wifes Quest van with 3.5 had a hard start situation that ended up being an easy fix.
Throttle body was filthy, unplugged the electrical connectors, cleaned it up with carb/throttle body cleaner, plugged it back in and all good since.
The electronic throttle bodies have kind of a high idle setting during cranking and if they get dirty they sometimes seem to stick all the way closed.