Hard to start after sitting

[AJRK]

My 2001 QX4 (134,000km/80,000mi) has been having some trouble starting lately if I don't drive it every day.

If it sits more than 2-3 days, it takes a while to crank. I know it's not the battery, I just replaced it last month. I am thinking it is fuel related.

Last week, I got it started one morning easily after sitting, but when I put it in reverse it shook briefly and then stalled. When I restarted it, it took a while to crank but then ran fine. No codes have triggered the SES light.

I always use top tier premium 91 octane fuel, and run a Lucas fuel injector cleaner every 2-3 months.

Has anyone had similar problems? I am wondering if it's the fuel pump? I also still have the original spark plugs in it, which I plan on changing soon, but if it was bad plugs, I would imagine the problem would be more consistent.

Any advice would be appreciated!

[Towncivilian]

Use something that contains PEA such as Chevron Techron or Gumout Regane instead. From what I have read Lucas FIC is mostly oil and has very little cleaning value. Marvel Mystery Oil is also a good lubricant and cleaner for the fuel system and is probably cheaper than Lucas FIC.

Ever changed the fuel filter?

Your spark plugs should be fine - they still have 25k miles worth of service per the maintenance schedule.

[AJRK]

Thanks, I'll look into those products.

I'm going to double check my service records but I'm pretty sure I changed the fuel filter about 50,000kms (30,000 Mi) ago. Can't hurt to change it again I suppose.

[Towncivilian]

I change it yearly. FSM recommends changing it only when the vehicle speed cannot be increased as desired, but Courtesy Parts recommends yearly on their site. I would definitely change it yearly if you run to empty often, as this may suck up sediment from the bottom of the fuel tank and clog the fuel filter faster. I also stick with top-tier gas from frequented stations, so I doubt a ton of dirt enters the fuel system - probably more dirt enters from the process of filling up (opening gas cap, etc) than from within the gas station's fuel tanks. But I'd rather pay $13 a year to help keep my fuel pump from additional needless strain.

When starting the vehicle, turn the ignition to "ON" first, which will run the fuel pump for 1 second to help vehicle startability. Then start the engine. This may help your starting issue somewhat.

[ARKQX33V6]

From your description check:
fuel rail pressure during stat up, your check valve may be bleeding the pressure down. Or as Towncivilian suggests turn the ignition to on, wait a second then engage the starter. While your at it with ignition only on can you hear the fuel pump engage in the rear end?

With your distance I think the fuel filter should be changed, also the plugs should be removed and examined. If they can be gaped check to see what they are at.

Does your car suggest premium gas, if not stop using it because if not required you can be plugging it up with carbon, which will alter compression ratio and knock sensor will adjust timing and if too far in advance will create harder starts.

[Towncivilian]

Does your car suggest premium gas, if not stop using it because if not required you can be plugging it up with carbon, which will alter compression ratio and knock sensor will adjust timing and if too far in advance will create harder starts.

The VQ35DE does indeed recommend 91 AKI (96 RON) or higher. Also, the FSM says there's no need to check and adjust the spark plugs between change intervals.

[ARKQX33V6]

Towncivilian can you trust the manual on the plugs, are the plugs platinum? What is recommended time distance for plug intervals?

Thanks for the update.

On another note: New Car Sales
2 days ago I went to the Infiniti dealer for the first time in 10 years. They told me Infiniti is a sports car, all of them? And they are all high compression and use the premium fuels. With retail prices in the $55K plus area and with Japan in trouble with delivering product, the salesman said they now do not have enough stock!

[Towncivilian]

Towncivilian can you trust the manual on the plugs, are the plugs platinum? What is recommended time distance for plug intervals?

Thanks for the update.

On another note: New Car Sales
2 days ago I went to the Infiniti dealer for the first time in 10 years. They told me Infiniti is a sports car, all of them? And they are all high compression and use the premium fuels. With retail prices in the $55K plus area and with Japan in trouble with delivering product, the salesman said they now do not have enough stock!

The FSM says replace every 105k miles for platinum-tipped spark plugs. No time-specific replacement interval. Cleaning is fine, just not regapping.

[ARKQX33V6]

Thanks Towncivilian.

My thoughts about spark plugs and manufacturers are this: The automakers know that we as consumers do not want to do work on our vehicles and to this end, by the use of various materials the makers can and do extend the time interval and the distance between change outs and replacements. This is a fact known towards oil, brakes, coolant etc. and as a consumer I applaud the automakers, but to a point.

Different materials when stuck together for a long time can have a detrimental effect on each other and can cause the materials to stick so good that getting them apart causes undue wear on them. Case in point is the spark plugs. Steel and aluminum with time passing these 2 materials can get jammed together and the cut threads in the aluminum heads can get ripped apart or worse the plug cannot be removed.

Although platinum tipped plugs are great the plugs themselves should be removed and the plug threads cleaned then an anti-seize compound applied to the threads and re-installed. The time for this preventive maintenance job will vary with use, but a 2-3 year time frame would be maximum and an annual removal and look see probably would be on the very safe side.

If you have ever tried removing a stuck plug in a bad position like #6 on an older QX4, you may appreciate the preventative maintenance job that should have been done.

In fact #6 position screams out for a platinum plug because of the design, but it should be cleaned yearly.

[Towncivilian]

I mistakenly replaced my spark plugs after only 30k of use. They were replaced by Nissan at 90k and I did not know. The plugs came out looking serviceable, and I believe they had no anti-seize on the threads. It was a waste of my time, but new plugs (with anti-seize) went in anyway. I unfortunately discarded the old plugs, but I could have swapped them in at 225k and ran them till 300k most likely. But I think we digress.

[AJRK]

Just a quick update: I hadn't had the problems for about a week, but it flared up badly this weekend, and it hadn't even been sitting at all. The only thing I can think of is the fuel level was below half, but I can't imagine that was the reason. It happened 2-3 times on Saturday. I went out for dinner and when I came out it took about 3 attempts to get it started. It would just crank and not turn over, except once it turned over and ran really rough for about 5 seconds before stalling. I have been turning the ignition "on" before starting the car, but this problem seems to be continuing. I'm going to replace the fuel filter asap, and I have put in a Chevron Techron fuel treatment, but I think the problem is rooted elsewhere.Still no codes coming up... Any ideas? Fuel pump? Injectors? Ignition parts?

[ARKQX33V6]

There are lot of things that will cause this sort of problem. Check the fuel supply that is the flow and the pressure in the fuel rail to and from the throttle. Examine the low voltage supply 12 V to the ignition, and the high volts at the coils, and the distributor, insides for crap and the electronic control.

When starting the starter as long as the engine actually turns over and loads up the starter, all primary controls need to be confirmed to give spark to the coils. A common problem may be preventing ignition. Test those common sensors to ignition.

[Towncivilian]

and the distributor, insides for crap and the electronic control.

VQ35DE (2001+) don't have distributors.

[ARKQX33V6]

Towncivilian are they distributor-less? I don't have such a new vehicle, but do have a 31 year old Goldwing that uses no distributor, the electronic switch gear through transistor(s) becomes more vital. The state of the battery is vital to primary controlled electronics.

Can somebody post the ignition system on this forum for a look see?

Guessing what the problem is from the comfort of a nice chair is tough, on start up:
The engine needs compression
Air
Fuel
Ignition
in the correct order and the correct amount, plus the ability to crank over at the right speed range , so the battery is also very important to allow RPM, voltage for ignition. If a partially charged battery is used, these problems will exist because the voltage is drawn down by the starter motor.
Start the car drive around for 15 minutes at least and then park and read the voltage, engine off. Battery voltage should be close to 13 V then but never lower than 12.6. Start checking out the easy things first.

electrical as starter amp draw, gasoline supply, air, compression, then check into the more complex things as
timing, spark, heat range of plugs, plug condition, grounding
then get into control of:
timing, ignition, fuel ratio

Because the engine finally starts but runs rough, things that come to mind
Lack of proper fuel and pressure, too low voltage, lack of fuel enrichment as in choking, advancement in timing or a stuck mechanism instead of retarded setting, lack of air plugged filter, poor ignition wires, connectors, spark coils, bad negative battery cable/grounding.

These are a few areas that need a looking at.

Is that vehicle getting good routine maintenance? If not you are going to have to examine all aspects of the car since you are having intermittent problems.

[Towncivilian]

Towncivilian are they distributor-less? I don't have such a new vehicle, but do have a 31 year old Goldwing that uses no distributor, the electronic switch gear through transistor(s) becomes more vital. The state of the battery is vital to primary controlled electronics.

The VQ35DE uses individual ignition coil packs, one per spark plug. This is the best diagram I could find after a quick skim of the FSM:

[AJRK]

Thanks for the replies.. To answer the questions about the vehicle, it's been extremely well maintained since new. Always been to the dealership, or a trusted mechanic. It looks brand new and has had any routine maintenance performed on time. I know the battery isn't a problem since I replaced it with a top of line Interstate about 2 months ago. I do recall replacing a coil pack a while ago... perhaps another one is on the way out.

It has been starting fine since the last time I posted anything here...

[ARKQX33V6]

Towncivilian, the multi pack ignition to me seems more complex, but the on/off switching arrangement is similar to a single coil, in as much as a transistor has to be biased to provide the pulse to the coil for HT energy.

A breakdown of the transistor switching may be taking place. I don't know the position of the electronics for this newer model but I would suggest a look see to discover anything extraordinary about the wires, transistor module and cleanliness of that area.

Because dealing with an intermittent problem makes every component related to ignition suspect.

I'm happy and disappointed that the car is running OK, but the problem is still hiding within the vehicle.

[AJRK]

So I took the car in for service yesterday and tried to get a diagnosis on the problem. They could not duplicate the problem or find any faults with the fuel pressure, or fuel pump. They were saying that on occasion the valve within the fuel pump can become sticky and there is no real way to find that without going into it. So I had the fuel and air filters replaced and a full fuel injector cleaning and the throttle body cleaning service, apparently the throttle body had a lot of carbon build up, so I guess we'll see what happens from here.

On another note, during their inspection I apparently have some o-ring leaking from an A/C sensor that they want $350 to fix, and they claim my rear shocks are leaking after only 30,000 miles!

[ARKQX33V6]

A TSB is out re hard starting and they blame carbon deposits. The reason I questioned high test fuel. Infiniti recommends a fuel cleaner by 3M and nothing else. But I have used Seafoam and arun of the mill carburetor cleaner but only when an oil change is due because these additive do get into the crankcase oil.

Check your intake horn and throttle plate for a black deposit around the internal circumference of the horn, also does your gas pedal stick. The deposits make the throttle plate stick and that is just the beginning.

I also use a marine 2 cycle oil that I dilute in the gas tank to keep valves from sticking, a quart lasts me a couple years for the QX4 and a 1980 Goldwing. I use 2 capfuls for 5 gallons. When running you should see no smoking.

Seafoam can be used the same way but in Canada it is expensive and in the QX4 I use 1/2 a bottle of Seafoam to a full tank of regular gas. Again there is no smoking.

Do not use Seafoam or any other additive to create smoking, the loosening of too much carbon at one time may leave you with a vehicle that cannot operate, be gentle with carbon removal.