I bought 3 new injectors and they came with new o-rings. Took off the IM about 3 weeks back and changed the rear 3 (1 was bad, didnt want the other 2 going bad during winter). Ran into misfire/hesitation/hard start problems (front injectors tested fine) so I changed out all the plugs and coil packs (bought a used set from someone local). Still had the misfire/hesitation/hard starts and the car was eating gas like crazy (filled up the tank with premium, was down to 1/4 mark after 140 miles)

Today I decided to pull the IM again to see what the prob was. The injectors tested fine so I pulled them out and noticed this:
(lost 1 of the smaller ones in the grass)


The aftermarket ones were a little too big and not as solid as the OEM ones. The upper larger ones were fine, but the smaller lower ones "ripped" into a smaller size causing my injectors to leak and flood the engine (hard starts). Changed them out with new OEM ones and the misfire/hesitation/hard starts are finally gone (might have to change out the oil again)

 

Can you give me any tips on replacing the injectors????

My Maxima has been running like crap and thought initially it was the Knock-Sensor. I think the code was 0304. But after replacing the knock-sensor it still was running like crap, so off the the local dealer to do diags.

Found that cyl#3 was mis-firing because of an injector out of range. Wasn't into giving them 7 bills to do the job, so I'm stuck doing it.

Bought the parts tonight. The injector is a re-man but originally OEM part but also includes the o-rings.

 

First go buy some OEM o-rings so you dont have to end up taking off the IM again like I had to (lube them with oil so it'll be easier to slide on the injector)

It really wasnt that bad for me since I didnt have any bolts in the back of the IM (only had to take off the 2 EGR bolts near the IACV - dont forget to put the EGR gasket back on). Heres a good how to: http://www.cardomain.com/ride/443899/2

Since its your first time, just start in the morning since it'll take a while (I spent ~3 hrs taking it completely off the first time, but a lil over an hour the second time). You might as well clean up some of the carbon buildup too since you're taking off the IM anyways. Took some pics: http://www.jatan.net/im/ (3rd one shows the clogged EGR tube)

Most likely your injector screws will be too soft (dont bother trying with a screwdriver first) so:
- Get a vise grip and grab the top of the screw, then twist the vise grip in order to break the screw loose
- After both of the injector screws are loosened, use the screwdriver to remove them
- Remove the top metal injector cap
- Put the 2 screws back on by themselves (leave the metal cap off)
- Use 2 small screwdrivers or something else as leverage to pop the injector out (there are small holes on the sides of the injectors - dont bother trying to force it out with a wrench)

I'll take some pics of what I'm talking about tomorrow morning

 

Grip the screw with a vise grip:

Turn the vise grip counterclockwise and you'll hear it "break loose" (then use a screwdriver to remove):

Take off both screws, remove metal cap, and then put the screws back about half way in:

Use small screwdrivers or something else that'll fit (I used an L key thing & screwdriver) and just push down on them, the injector will pop right out without any probs:

You can see that I tried to pull the injector out before with the vise grip and the top plastic was just breaking off lol

Good luck - it really isnt that bad