HELP! Problems with AUTO

[MPittma100]

Misfire

High TC,

No doubt you have gotten rid of the problem with the "tune up". Next time (if) you have a misfire code, switch the plug that caused the code with any other cylinder plug. Remove the code (with scan tool) and see if a reoccurring misfire code follows the switch. When a misfire occurs, a code for it will show up quickly.

Not sure if the auto parts outlets scan tools have the code removal feature, but they are available.

When you have multiple codes, they are prioritized in order by the software. Normally the first code is the one to be concerned with.

If your engine light does not turn off by itself, you will have to have it cleared. You may check your vehicle manual and find out that you can clear the code manually. Some vehicles will clear via battery cable and/or computer fuse temporary removal.

Hey again folks,

Thanks again for all of the brainstorming ideas and info. Fortunately, the misfire plug was #5 which was the front right one on this V-6, and I was able to get access to the injector electrical connector WITHOUT having to pull the intake plenum/manifold, just pulled the Dist. Cap and wires out of the way. Tested it with the Ohmeter, 12.4 ohms, within spec with the others I checked....so it wasn't FRIED.

Pulled the Spark Plug...had a little color on one side of it, but not a definitive streak!



THEN...looked more closely at the other side of the electrode!


The OEM's were Double Platinum....these were just "single" platinum....and so I guess that partly made for the wear at only around 40K since install!?

Then I looked more closely at the plug cap....for the #5 and 3 clyinders, it uses these 12" long hard bakelite/plastic tubes to be able to reach down thru the intake plenum to the plug! The one on the right is the misfiring #5.. it looks like it might have had a crack/imperfection in the casting and that darned "Electrickery" found a way out the side and to the engine....there was some sort of brace/bracket very close to that location down on the engine... so I am assuming that it was shorting out the side of the cap!?



SO...I decided to bite the bullet, and replace all of the plugs with Double Platinums, the plug wire set, AND the Dist. Cap and rotor....I had been cleaning the cap periodically by scraping off the arced/corrosion that builds up on the inside flat side of the cap plug pins that the rotor arcs to when distributing the power!



Fired it up, and was hitting on all 6 cylinders again. The check engine light is still on, but not blinking....went to the auto store, same codes as before, they stated that I'll have to drive it for 30 or so miles and once the ECM realizes that it's behaving again, it will clear itself and turn off!

SO...it looks like my fuel injector was having an ignition problem....sounds familiar doesn't it! Happy camper again!!!

T.C.

[TopCatGr58]

Problem Solved: FEEDBACK!

Hey again folks,

Thanks again for all of the brainstorming ideas and info. Fortunately, the misfire plug was #5 which was the front right one on this V-6, and I was able to get access to the injector electrical connector WITHOUT having to pull the intake plenum/manifold, just pulled the Dist. Cap and wires out of the way. Tested it with the Ohmeter, 12.4 ohms, within spec with the others I checked....so it wasn't FRIED.

Pulled the Spark Plug...had a little color on one side of it, but not a definitive streak!



THEN...looked more closely at the other side of the electrode!


The OEM's were Double Platinum....these were just "single" platinum....and so I guess that partly made for the wear at only around 40K since install!?

Then I looked more closely at the plug cap....for the #5 and 3 clyinders, it uses these 12" long hard bakelite/plastic tubes to be able to reach down thru the intake plenum to the plug! The one on the right is the misfiring #5.. it looks like it might have had a crack/imperfection in the casting and that darned "Electrickery" found a way out the side and to the engine....there was some sort of brace/bracket very close to that location down on the engine... so I am assuming that it was shorting out the side of the cap!?



SO...I decided to bite the bullet, and replace all of the plugs with Double Platinums, the plug wire set, AND the Dist. Cap and rotor....I had been cleaning the cap periodically by scraping off the arced/corrosion that builds up on the inside flat side of the cap plug pins that the rotor arcs to when distributing the power!



Fired it up, and was hitting on all 6 cylinders again. The check engine light is still on, but not blinking....went to the auto store, same codes as before, they stated that I'll have to drive it for 30 or so miles and once the ECM realizes that it's behaving again, it will clear itself and turn off!

SO...it looks like my fuel injector was having an ignition problem....sounds familiar doesn't it! Happy camper again!!!

T.C.

[vedgar]

Simplified diagostics for misfire.

Since the check engine light was flashing, the misfire was what we call a dead misfire. (Not intermittent) Cylinder 2 is the culprit and the knock sensor code can be ignored at this time. Check to see if you have spark at the end of the plug wire (plug in another spark plug and ground it. Second, pull #2 plug and see if it is wet. If wet, replace it . If not wet , use a stethoscope and listen to #2 injector. It will tick lightly if it is working correctly (compare to others). If it does not tick and the plug is dry, replace the injector. If it ticks and the plug is dry it may be cleanable. Not to be forgotten, make sure you have good compression on that cylinder. Good Luck
Vance

[IanDMacDonald]

Screw all this diagnosing crap, buy a new truck TC!!!!!!!! Get the new Tahoe! Lol, jk. Pain in the butt, I know.

[ViperRon]

TC The 2004 Xterra has a history of the bearings in the distributor going bad and causing the issue you are having. This is a common problem but also people have been lured into replacing it with no change. On your model there are 4 oxygen sensors on the manifold pipe that read to ensure clean burn and change fuel flow to injectors and timing change to adjust performance according to outside environment. These in part take the place of old fashion manual choke. The other part, EGR Valve, works in conjunction with these to supply heated air from exhaust to the intake to assist atomization of gas and air. As mentioned the EGR can clog and stick causing the same issues but often times have sensors that monitor open close position and give specific error code if it does not move. If it were totally clogged you would normally have seen performance and power go down hill over a period of time. The knock sensor is a safety and monitor feature to ensure smooth rotation of the engine that helps identify miss or power loss from cylinder that can be caused by anything plug, wire, sensor, computer, distributor, EGR, Map, burnt valve, etc...

I can not find it online search but either auto parts store or dealer should have the OHMS readings and wire position for the oxygen sensors in your system so you can read them with a meter. It may be in the manual or on sticker under hood. Most have a resistance range like from 2 to 4 ohms when not in use. You should also check to ensure 12 volts gets to them with key on and the connectors are not melted or burnt a common issue. You can check these for free. You can check them outside the vehicle with a torch to ensure they change but that is a bitch to do at times and you can screw them up with too much heat. You can pop the EGR valve assembly off the manifold and check to see if its clogged for the price of a gaskets (cheap) but it's a bitch some times and bolts shear off causing you to wish you had not touched it. You should check all vacuum hoses for leaks and poor connections for free but be careful some break darn easy after use and the right hose isn't cheap. I don't think its plugs or wires or distributor cap you would have found that before putting up the note.

Beware of dealers and some repair shops as they many times sell the manifold pipe catalytic converter and oxygen sensors all as one big bill expense for this.

[SFerinTEXAS]

plug off vacumn line to egr. If that system is the culprit it should run better just not efficient.

Not counting a stuck open egr valve.

Have a 4.2 fd v-6 that plagued me with a #6 missfire code.After a few years it became almost undriveable.Found out some egr passages in the intake were clogged causing uneven fuel mixtures in the cylinders throwing missfire codes.
after the repair its like a new motor

[SFerinTEXAS]

plug off vacumn line to egr. If that system is the culprit it should run better just not efficient.

[DiverRay]

TC,
I ALWAYS replace wires and plugs at the same time on newer autos. The "new" wires seem to go bad when you don't. If you didn't put new wires on, that would be my FIRST repair. The knock sensor probably hit because of the misfire. I don't know what wires are for that, but they should be less than $100 for good ones. My ML320 has 2 plugs per on a V6, and the 3" long wires are $140 per set at the CHEAPEST place I can find....

[Radioguylogs]

It would be easy to mist the plug wires with a spray bottle.

[TopCatGr58]

Hey again,

Thanks for the info. I did have it read at the auto store, and put the error codes in my FIRST POST, but they don't tell you when the injector goes bad, just things like MISFIRE and such...which is what I had. With all of the real MECHS on here, I was hoping for more than just WAG's with all of the history and diagnostics I had already done/had done!

I have done some more net searching and have found notes about the distributor bearings problem. I also found info about how to TEST the injectors by using a MM/Ohms....should be about 12 ohms....if much higher, ie. 17 or so....stuck closed....if much lower....stuck open.....or possibly fried. Just checked....they aren't CHEAP! And it's suggested to replace ALL of them at the same time.....due to extra work of having to remove the intake manifold to gain access....replace gaskets, etc.....but I don't have room in the budget right now for this....just put on $700 worth of tires a little over a month ago. So....if I replace 1 faulty injector(if that's the problem) then perhaps I'll get some time of full functionality before any other injectors go bad, so I'll have more time to get more $$ in the bank! Bills, bills, bills!

I'll let you all know what I find out as I persue this tomorrow!

T.C.

[trbig]

Autozone/Oreilly's or the like have readers that they plug into your vehicle (Usually right under the dash under the steering wheel) they can tell you what kind of code the engine light is coming on for and they do it for free. It'll usually help narrow things down a lot closer than a bunch of beer drinkers on a motorcycle website throwing out WAGs from their computers. Get those codes and you can look online to find the most probably culprit with that particular vehicle.

[Bikes]

Dont rule out a bad, new plug......

[ViperRon]

I know you would expect this to show as another error code but my experience with Oxygen sensors is they have never shown up in the error codes for me. Just show up as hard start very poor idle bad mileage and poor power. I do not know how many miles you have on yours but they do go bad and cause everything to be off. They tend to start failing with problems after carb cleaning or cold weather for me. If they recommend replacement in 50K and you have 90K on the sensor might be time for replacement. You may have 2 of them in your system I generally replace both at the same time.

The other issue I have seen is getting diesel fuel mixed with my gas once. I was not the only person that got nailed when the tank at the store was topped off with diesel instead of gas. You can usually smell it in the gas.

[IanDMacDonald]

A dirty FI is possible I guess. Let's cross our fingers for an easy fix.

[IanDMacDonald]

Hey TC- I got a little dirt under my nails with Xterras (just kidding, I wear gloves). First thing I'd do is go open the hood now and see if u can see any arcing. Second, those distributor rotor bearings go bad. Check for play in it.. Third, u could pull your plug to see if it's wet. If so, could be an intake leak, causing coolant to sneak-in.