coachholland

iTrader: (2)

I've run into some really odd stuff on my Maxima that I recently purchased and was hoping I might be able to get some direction here.

To give a bit of a background, I've gone ahead and changed out the plugs, changed all fluids, new fuel filter, air filter, etc... run injector cleaner through several times and cleaned out the throttle body.

The issues that I'm running into are multiple problems. First, I have a bad miss. I traced it back to the back cylinder on closest to the passenger side. I pulled the coil on it and no change in the way the engine runs. I replaced the coil with a used one and still no change. I swapped it with a coil on a known good cylinder and still that cylinder isn't firing, at least at lower RPM's. I have major hesitation issues at lower RPM's, but it seems like if I get the RPM's up at highway speeds or ride around at 45 MPH+ with overdrive off, the engine seems to smooth out. I have a digital volt/ohmeter and I am getting juice, but it just seems like like cylinder doesn't fire.

Second problem I'm having under the hood is that my engine doesn't overheat, it *underheats* when driving around town. If the Maxima sits at idle for an extended period of time, the temp gauge goes up to normal range, but once I start driving through town or on the highway, it visibly starts decreases until it bottoms out in the cold range. I would guess that for a faulty t-stat staying open if it were staying cold at idle, but the fact it only does it while I'm in motion puzzles me.

For those that ask, yes I am getting CEL codes. O2 and ERG issues both, however in my experience neither of those would be the cause of a cylinder not firing at low RPM's or the engine cooling abnormally. Those codes would normally lead to an intermittent misfire on any vehicle I've had before.

I've been reading up around the forums since I joined up a little over a week or so ago and I've not run into anything like what I'm going through. Help!

pmohr

iTrader: (26)

For number 1, have you checked out the plug and injector?

For number 2, it's possible the thermostat is faulty. Sounds just like how my car acted when I took the thermostat out. At idle you've got no airflow over the radiator to cool off the antifreeze, but while driving you do. Explains why it would cool down while in motion.

coachholland

iTrader: (2)

Thanks for the ideas. I forgot to mention, I did "sound test" the injectors and all have a uniform sound. The fronts are easy enough to volt test, but of course the rears are a different story, so I just did the long screwdriver test. No difference in sound on any injector. I also changed out the new plug with several different of the old ones just to make sure that I didn't happen to get one DOA out of the box. No difference there.

And now that you put it that way about the t-stat, I have to say duh, why didn't I think of that? lol I'll give that a shot and see about the excessive cooling.

Still loss as to what to do next on the miss though.

99BlackMaxMS

iTrader: (85)

Problem 1: You got a junk injector on that cylinder.

Problem 2: Try a new thermostat. If that isn't the case, try fixing the EGR, even though that usually tends to just lead to a high idle and shouldnt have much to do with the temp of the coolant.

pmohr

iTrader: (26)

If it sounds the same, it could just be clogged up. The electrical portion of it would still operate (hence the uniform sound across all 6), but it would have no flow. Pulling the fuel rail doesn't take but 20 minutes, then you could crank it (or just prime the system) and see if they all have a uniform spray pattern (should be cone shaped).

coachholland

iTrader: (2)

Now that's a possibility. Would that explain why the engine seems to smooth out at higher speeds? I'm not certain on the way the injectors work, but is there more pressure going to the rails and injectors at higher RPM's?

pmohr

iTrader: (26)

It's a possibility that higher pressures are able to force the fuel past the blockage, but couldn't really say.

Injectors are relatively cheap ($8 for one at my local pick and pull, works perfect). I'd definitely pull the rail and check spray pattern if it were my car, though. Does the plug in that cylinder look any different from the others that are operating correctly?

coachholland

iTrader: (2)

EGR is going to be my project for next weekend. Unfortunately having four or so hours to spare is hard to come by for me. I *definitely* know it needs to be done though, especially with the miles that are on the girl.

coachholland

iTrader: (2)

When I pulled the original plugs that were in the car when I first got it (autolite coppers, not NGK's... ugh...) they all looked the same. I've put a couple of thousand miles on her since I bought it and changed plugs and after I pulled them, honestly they all look them same yet again. I'll be heading out to the local yard here Monday and giving a different injector a shot though. Anything special I should know about changing one out that will make it go easy? I thought just from looking at it that it required removing the manifold. Seems like the haynes manual said I have to remove the manifold as well to access the rear bank ones.
EDIT: No gas smell on the bad cylinder, btw.

pmohr

iTrader: (26)

UIM has to come off, yes. That's no biggie, it's just the small **** that's in tight spaces that sucks. Basically, EGR pipe (which is a LOT easier with the IACV off) and the rear support brackets. I never did replace those rear brackets, they are just a pain in the *** IMO.

Two screws for the injector caps (impact driver is best, but a screwdriver will work if you put enough downward force on it; they love to strip out. Failing that, vice grips FTW). Then, pull upwards while you rotate it side to side or just plain spin it around, otherwise you'll be spending forever to get the damn thing out. Those o-rings are in there extremely tight.

On reinstall make sure you lube them up (I just wiped some oil off of the dipstick, because I'm just that cool) or you'll likely rip the injector o-rings.

coachholland

iTrader: (2)

Impact driver would be great, but looks like it will be the screwdriver for me. i've got reactive arthritis (at the grand ol' age of 34 from a samonella infection a year and a half ago) in my hands, so hopefully it's not going to need too much strength to get out of there.

lol, I like the dipstick idea. I'll definitely be using that. I appreciate the help and will be giving this a shot next week after I can get to the local salvage yard to grab a new injector. Wish me luck and I'll update with the results.

I've got some interior gremlins I'm going to work on as well, but a new thread for that one. Too much for one thread to cover without it getting confusing.

pmohr

iTrader: (26)

No problem. The injector cap screws will be quite tight, and quite easy to strip out.

densetsu

iTrader: (1)

use a hammer to tap the screwdriver into the grooves well, keep force downwards and turn, they should easily come off.

coachholland

iTrader: (2)

densetsu, that tip came in handy because even with my full weight on the screw, it felt like it was getting ready to strip out. Hammer did the trick.

pmohr, thank you for the help with this. I just fired it up and I'm finally no longer getting the miss on that cylinder. I'm off to work, but will be traveling quite a bit today. I'm looking forward to actually running on six instead of five. You rock.

t-stat is still likely a weekend job for me. Changing out the injectors was enough for a few days for me, lol.

coachholland

iTrader: (2)

Thought I would update this thread with some more final results for anyone running a search on this problem (or related) in the future.

After installing the new injector, I reset the PCM - ECU. I had previously been getting a ton of codes, most notably knock sensor, o2 sensor and EGR. It's been driven pretty heavily the last two days and those codes have not returned. Previously when I had reset the PCM, all the codes had returned within a five to 15 miles of driving.

So, just for anyone to note, it's possibly that those codes can be thrown apparently from a faulty fuel injector.

ibthor

Thanks for this thread!...

My car started running rough a couple weeks ago, and I took it in and had it scanned. They told me it was the ignition coil on cylinder #2. I replace that, only to find the rough running continued. I then started pulling ignition coil wires and injector wires with the car running and figured out I had the right cylinder, but apparently the wrong part. I swapped ignition coils with the next cylinder, and the problem stayed at #2. I then swapped injectors with the next cylinder, and the problems followed the injector. Once I replaced the injector, the rough idling went away.

So, a couple of unnecessary parts and a couple weeks later, my maxima runs again. I do have a 2002 maxima, but it was this thread that helped the most, so, again, Thanks!