dkpowers

Good afternoon forum!

Here's the scoop: '98 Maxima, my wife told me her car was running rough, brought it to O'Reilly's. On the drive over, the check engine light was flashing (which I know is no bueno). But eventually it stopped flashing and stayed on. Major code that I pulled was P0302 (cylinder 2 misfire). Cleared codes and limped back home.

Did some research, biggest suggestion was to replace ignition coil. Replaced coil with used one from a parts store (I guess Nissan's don't like aftermarket parts), started car, still rough, check engine light back on.

Changing the spark plug didn't change any of the symptoms... Pulled code, same P0302. Cleared it, switch ORIGINAL coil from cylinder 2 to 4 (and vice versa), same symptoms. Drove the car around for a while, check engine light came on, same P0302.

So what's next? It doesn't appear to be the coils or the plugs, what else? I maybe should mention that the original ignition coil from #2 had some oil around it while #4 has completely dry.

I appreciate any input, and thanks for looking!
Dan

JvG

The injector.

dkpowers

Fast update: a buddy's cousin (who is a respectable mechanic) came over to the house and ran some tests. He said that compression in #2 is half of the other cylinders which is causing the code P0302. He said to "start looking for another car."

He showed me the compression tests and I believe what he says, he just didn't go into detail as to what is causing the low compression and how much is it to fix if I chose to. I most likely will be seeking a second opinion just to confirm.

Thoughts?

JoshG

your mechanic seems like he wants to do some easy jobs rather than hard labor work..

JvG

If the compression is low, no ignition coil could fix that.
Our cars need to have their valves adjusted one in a while because they are adjusted with shims instead of hydraulicly.

It's possible that a valve adjustment will fix this issue.

If it does not, you might have a burned valve. If so , the best fix would be another engine. Or sell the car.

dkpowers

Thanks for your input! The repair shop just called back with their diagnosis and also says the injector. Parts and labor about $320. Should I just have them do the work, or can I do it myself (I'm not super mechanically-inclined)? Does the injector malfunction also cause low compression?

maximaxi

The front cylinders (2,4,6) are relatively easy because you don't have to take off the intake.

However, the screws can be a pain to take off. You'll need a put vice grip around the screws to unscrew them. Other than that, very easy.

I had to replace #4. it took me about 15 minutes, and I'm ok but not great with doing my own work. The hardest part was just getting the screws off.

I recommend Bosch 62027 or Hitachi FIJ0023 (Beck/Arnley is also good, but I forget the part number ATM). It's a reboxed OEM injector. You will have to buy the o-rings separately (buy Beck/Arnley brand). Total price around $70 or possibly less.

JvG

Injector does not cause low compression. A mis-adjusted or burned valve does. Or a bad piston ring. Have this diagnosed before you spend more money on the car.

The Wizard

iTrader: (43)

$320 to replace any of injectors 2,4, or 6 is highway robbery. Pick a refurbished one off of ebay for $15 to $20 and install it yourself. 10 minute job with the right tools.

JoshG

lol $30 for parts, 290$ for labor, all about the business.

JvG

Your mechanic told you that you have low compression on one cylinder. It does not make financial sense to invest in the car until you get this checked out. A valve adjustment might fix this. If not, you are looking at a replacement engine.

If you spend money on replacing an injector, you still have low compression. No point replacing an injector on an engine which you may need to replace.

JoshG

I would just replace the injector like wizard said, better to do it than not.

JvG

if the valve is bad, the engine might need to be replaced. So why pay for an injector?


dkpowers needs to make a decision about the engine. the compression won't fix its self.


Im trying to save him money, work, and grief.

The Wizard

iTrader: (43)

These are tough motors, so I'm having a hard time believing that cylinder #2 failed. What is very common though is injector failure. I'm hoping for a mis-diagnosis with the compression number. If you don't want to spend a dime, switch injectors #2 and #6 and see if the problem moves.

JoshG

Agreed, This guy here knows these cars, again these motors are bullet proof no matter how hard you try to abuse it..alot of mechanics like to say "You need a new engine" cause they don't want to go through the hassle of going into diagnosing it and finding what really is causing it.. so they rather do it the "Easy" way for them, these are so-called lazy mechanics that want to do easier work and still get paid.

but in all seriousness, try that method of switching injectors.

JvG

also take compression readings again. Agreed that valve failure is not common on these engines.

jerrod99_se-l

When your shop did the compression test....did they remove all the coils so the engine wouldn't fire? Did they take compression readings on all 6 cylinders or just one? Typically from what I've seen in the past when checking compression all cylinders are checked and recorded...then the compression of all the cylinders must be within 15 percent of the highest compression...just my .02

JvG

Rather than remove the coils so that they won't fire, all you need to do is remove the fuse foe the fuel pump. No fuel then.same result

jerrod99_se-l

Good idea...saves time...I just do things the way I was taught

dkpowers

Thank you all for bouncing your ideas off of this thread! My wife and decided to do the $320 gamble (I know, highway robbery) and replaced the injector so that we can try and get back to being a two-car family ASAP. As it turns out, the car is running smoothly again! Maybe a mis-diagnosis of the low compression?

Thanks again for all the input!

The Wizard

iTrader: (43)

Welp, I called it.

Glad your Max is back on the road.

Mechanic got to close early that day...

The Wizard

iTrader: (43)

And FTR, this is the wrong way to remove those soft brass screws. This should be plan Z.

Using a ratchet and a socket with a nice quality number #2 phillips end, push down hard on the head of the ratchet while your other hand turns the ratchet.

Optional:
Replace soft brass screws with better hardware. Go to Lowes and buy replacement hardware with allen key heads so you'll never have this problem again. The size you need to replace the two brass screws holding the FPR are M5-0.8 16mm. Don't forget to pick up some M5 lock washers too.

JvG

Congratulations. Glad it worked out for you.