Troubleshooting coil packs and injectors on 2007 Nissan Quest

[davem1111 2,030]

I thought I'd throw this in here, since I know a lot of you have a variety of auto mechanic experience.  Any ideas are very welcome.

 

I have a 2007 Nissan Quest minivan, 3.5L EFI engine. The van was a gift from my wife's mother a few years ago, after our daughter totalled my Subaru Forester.  Her mom wasn't driving any more and was generous enough to just give it to us. It has about 155K miles at present.

 

I've had to do various things to it, like replacing the left front axle and wheel bearing, alternator recently, and a few years ago, 2 of the coil packs (it has individual coils for each spark plug) and a few cam/crank position sensors. Replaced all 6 spark plugs at that time also. It had been running great until recently.

 

The car started missing and bucking, which was reminiscent of the previous bad coil episode.  It threw a code P0302, which means "misfire on cylinder 2", which thankfully is the front left cylinder. At one point it also threw a P0300, which is just a "general misfire", i.e., your guess where is as good as mine.

 

(To get to the back ones, you have to take the cover assembly off the area where the wiper motor and wiper arm levers are housed, then take the intake manifold off along with lots of wires and hoses - not something I wish to repeat any time soon, but still easier than the alternator... but I digress.)

 

I bought a new coil pack at O'Reilly, cost me about $70. Cleared the codes, replaced the #2 coil pack, and it seemed better but before long it threw the same code again.  I tried swapping the spark plugs between #2 and #4, and if anything, it ran worse. Swapped them back. About the same.  Swapped the coils from #2 and #4, seems to run a little better but didn't take a test drive.

 

So, I'm wondering if the problem is with the fuel injector(s).  Does anyone know how difficult these are to change out?  I'm only planning to do the front 3 right now, unless the problem persists, then I'll dive in and get to the back ones also.  I'm probably going to buy a six-pack of coils, spark plugs, and injectors and if I go into the back I'll replace everything so I hopefully don't have to do that again... ever. Our son is learning to drive, on his permit now, and this will be his car till he can get his own.  Used cars are so dang expensive right now, it makes sense to try to keep this one going. Several hundred dollars more invested in it is no big deal, and since I do my own work I save a TON on labor.

 

Thoughts? Suggestions? 

[ri702bill 8,316]

9 hours ago, davem1111 said:

I'm probably going to buy a six-pack of coils

My son had to replace 2 of the 6 direct mounted coils on a Mazda Tribute (Ford Escape) years ago. Since it was such a PIA to remove covers, etc, to access them, he bought 6 aftermarket new ones sold as a set (and cheaper than two new OE ones) and kept the "good" 4 OE ones left if needed. We also diagnosed a cold start stumble / rough Idle vacuum leak at the 2 piece intake manafold gaskets. The intake gasket would "reseal" itself once it warmed up, but would occasoinally throw a code. Changed them too at the same time. No problems, cleared the codes, ran well.

[Pullstart 62,838]

Dave, your logic is smarter than an Autozone scanner program’s!  Move the parts, try to pinpoint the fault, realize you need fuel for fire.  
 

A couple general notes on swapping fuel injectors… I’ve done a few sets this year for people.  
 

Find the fuel pump fuse or relay.  Pull it.  Start the engine until it stalls.  Perfect way to bleed the high pressure fuel system.  
 

I like to find the firing order of the engine, pull all the spark plugs to ease rotating the engine by the crank pulley.  Pull all the injectors, stuff rags in anything that could hold dirt, use a wire brush on a drill to clean the injector hole while that cylinder is at top dead center and an air chuck in the spark plug hole pushing the debris back out the injector hole.  If it’s not feasible to get to the spark plugs, you might could blow air in the intake while wire brushing.  Get that hole clean, regardless.

 

Use a dielectric or general service grease on the o-rings while doing the reassembly.  It helps everything pop together well.  It also helps create a second form of seal if any debris is present.  It also helps with the next time if it ever needs to be popped apart again.

[davem1111 2,030]

Some great advice here - thanks!

9 hours ago, ri702bill said:

My son had to replace 2 of the 6 direct mounted coils on a Mazda Tribute (Ford Escape) years ago. Since it was such a PIA to remove covers, etc, to access them, he bought 6 aftermarket new ones sold as a set (and cheaper than two new OE ones) and kept the "good" 4 OE ones left if needed. We also diagnosed a cold start stumble / rough Idle vacuum leak at the 2 piece intake manafold gaskets. The intake gasket would "reseal" itself once it warmed up, but would occasoinally throw a code. Changed them too at the same time. No problems, cleared the codes, ran well.

 

Hmmm... didn't think to check that.  I did find a vacuum hose that had rotted and broke off just past the nipple, luckily it was long enough to trim back and put back on.  More on this below....

 

 

7 hours ago, Pullstart said:

Dave, your logic is smarter than an Autozone scanner program’s!  Move the parts, try to pinpoint the fault, realize you need fuel for fire.  

 

A couple general notes on swapping fuel injectors… I’ve done a few sets this year for people.  

 

Find the fuel pump fuse or relay.  Pull it.  Start the engine until it stalls.  Perfect way to bleed the high pressure fuel system.  
 

I like to find the firing order of the engine, pull all the spark plugs to ease rotating the engine by the crank pulley.  Pull all the injectors, stuff rags in anything that could hold dirt, use a wire brush on a drill to clean the injector hole while that cylinder is at top dead center and an air chuck in the spark plug hole pushing the debris back out the injector hole.  If it’s not feasible to get to the spark plugs, you might could blow air in the intake while wire brushing.  Get that hole clean, regardless.

 

Use a dielectric or general service grease on the o-rings while doing the reassembly.  It helps everything pop together well.  It also helps create a second form of seal if any debris is present.  It also helps with the next time if it ever needs to be popped apart again.

 

Thank you for the kind words, @Pullstart - coming from you, that does mean a lot to me.  I try to think these things through logically.  Being on the mild side of the Autism/Asperger's spectrum, with a touch of ADD hyperfocus and a bit of OCD, I like to latch onto these things and keep at it till I figure it out. 

 

Hadn't thought about bleeding the fuel system. 

 

Regarding feasibility of getting to the spark plugs - front 3, easy.  Back 3, PITA (removing intake manifold, etc.). If I need to do that again, I will replace all 3 plugs, coils and injectors back there.

 

Interesting update:

 

I did 2 things to the car yesterday:

 

1) I repaired the broken vacuum line as mentioned above. It went to some kind of cylinder mounted on the intake, with another line going out. Not sure what that thing is or does, may look that up later.

 

2) Even though I read that you shouldn't have to set the gap on Iridium spark plugs, I checked them anyway, and #2 was a bit wide. Found my old feeler guage, which you can hardly read the numbers on. But I got it close enough I think - gap is supposed to be 0.044", used a caliper to get the feelers to around that, and re-gapped that plug.

 

Car is running great today!   So, which was it?  Vacuum, or plug gap?  Or a combination? 

[ri702bill 8,316]

8 hours ago, Pullstart said:

Use a dielectric or general service grease

Where's Pete?????

[ri702bill 8,316]

35 minutes ago, davem1111 said:

the broken vacuum line

If there is one that failed - guess what?? - engine heat, ozone, and time will eventually render all the engine vacuum lines unserviceable. Not to mention rodents like mice - they destroy thinga a LOT faster !!! Good work.

[squonk 41,072]

More than likely the vacuum hose. Low vac to a sensor will tell the conrtrol system to load up the fuel. Depending on where the hose is, it could cause the cylinder it's connected to to lean out and cause a skip/misfire.

 

Such an incident on a V.I.P.'s wife's Oldsmobile got me a free shake at Mcdonalds, $100 in tip/bonus and Employee of the Month! 

[davem1111 2,030]

31 minutes ago, ri702bill said:

If there is one that failed - guess what?? - engine heat, ozone, and time will eventually render all the engine vacuum lines unserviceable. Not to mention rodents like mice - they destroy thinga a LOT faster !!! Good work.

 

Yeah, I should probably inspect them all, and better yet, just plan to replace them all.

 

Oh, on the subject of mice... I found out a few years ago with my Subaru Forester (before it got totalled) that mice had eaten through some of the wires that go to the back inside the rocker panel ? at the base of the back door on one side. Rendered the rear airbags non-functional and threw codes.  Dealer wanted $1500 because they said they'd have to replace the entire rear wiring harness.  I just soldered the wires back together and insulated them.  What I also learned is that some manufacturers have started using a soy-based jacket on wires, which sure smells and tastes like food to mice (not that they seem to be very discerning when it comes to what is edible or not...).  Yeah, let's make our wire jackets edible - what could go wrong! 

[ri702bill 8,316]

12 hours ago, davem1111 said:

which sure smells and tastes like food to mice

VW had an incedent here in NJ , I believe about 10 years ago. Fifty or so new cars, parked near the water, mice chowwed down on all the underhood wiring - OOPS!!