04 5VZFE eating spark plugs, and missing.

Hello All,

Thought I'd get started with a quick question. I have an 04 with the 5VZFE V6.

Bought it used, had it checked over thoroughly with a trusted mechanic. Replaced coils (those are rediculously expensive) wires, fuel filter, plugs.

First problem, it started missing, found that the electrode in the plug had been eaten away to a point. Was told to buy double platinum plugs, but it didn't explain why it was happening. This was after about a years worth of driving.

Yesterday, it started missing, so we pulled all plugs and they looked fine, replaced the#5 from what the computer said was bad, and it seemed to fix the problem, but it started running rough again today.

I'm thinking now, mybe bad wire/coil, (hope not), or maybe a bad plug, but NGK has a fantasitic record.

Any suggestions, comments would be greatly appreciated.

 

Correct plug wire on the correct plug?

 

Use only NGK or DENSO dual electrode plugs for exactly that reason.. Plugs are a 30k maintenance on the 5vz, incorrect plugs will wear out much quicker.

 

Thanks for the suggestions.

Yes, using NGK's on the plugs (duel electrode, ones recommended for application), and the wires are right, (it has run well, so I know it's not crossed wires) not NGK though. But will check just in case!

Having them tested tomorrow to see if anything bad on the coil/boot and wire.

Was told, possibly a fuel injector, hoping someone else might have encountered the same problem.

Thank you again for your ideas!!

 

When you pull it, is the plug black or wet? Check the gap on the plugs. Sometimes they are off out of the box.

 

Thank you x2468,
No, plugs were dry and gray, do need to check gap again.

Thanks!!

 

Can you take a pic of it? A perfect air/fuel mixture should yield a golden brown plug (like perfectly made flapjacks). Gray could mean it's running lean, if it's on the whiter side.

 

Not to beat a dead horse, but i actually installed NGK single electrode plugs in mine 45,000 ago and i actually got better mpg's with 87 octane and the truck ran better. Recently switched back to the copper dual elctrodes and im getting alot of pinging with 87 and actually run 89 in it now, better mpg and runs smoother. When i removed them they still looked really good.

 

Old plug wires will cause misfires. If not, then start swapping the coil packs and see if the misfire jumps to different cylinders

 

If you can get access to a scantool or take it to a shop with one, scan the Long Term Fuel Trim % data for both cylinder banks. I'll bet you see the bank with the problem spark plug running at a significantly higher fuel trim % than the other bank. If so, this indicates you have fuel delivery problems on cyl 5.

 

Wanted to say thanks to all who offered suggestions.

I've thought it was bad gas, (so I ran it to empty, and put fresh gas in) with the missing, now its just jerking along. We did find a mis-wiring on the plug wires, not connected plug boots, but that hasn't fixed the problem.

Check engine light is still on and took it to auto zone to see what it is coming up with, and got error codes:

P0300: 1. Lean Air/Fuel ratio - fel pump
2. Faulty MAF/VAF sensor
3. Large vacuum leak
4. Ignition system fault

P0302: 1. Weak/missing spark
2. Plugged fuel injector
3. Engine mechanical fault
4. Large Vacuum leak specific to cyclinder

P0303: 1. Weak/missing spark
2. Plugged fuel injector
3. Engine mechanical fault
4. Large vacuum leak specific to cylinder

Not sure of what to do, or where to look? The ignitor? Vacuum hoses seem to be good, need to check in the light of day. Have run injector cleaner through it at high concentration.

Where is the Major Air Flow / Variable air flow (VAF) sensor?

Will clean all the connectors with contact cleaner, and if nothing seems to help, to the dealer, which I hate the most!

Thanks for everyones help!!

JJF

 

The MAF sensor is located ontop of the airtube running from the filter to the throttle body. Its held in with 2 philips head screws, and its got a sort of orange glass plug thingy inside it, thats the actual sensor. You'll need to buy MAF Sensor cleaner at autozone, and DO NOT TOUCH THE DAMN SENSOR. Dont touch it with your fingers, Q-tips, Brushes, or the plastic extension hose from the can. BAD.

If that plug is coated, it may look dark brown/black (common with guys running oiled filters)

Then pull your air tube off the throttle body and clean your brass butterfly valve. The crap typically cakes on the backside of the top-lip, and the bottom of the lower lip. Scrub it with a tooth brush.

I would really consider going to autozone/orielly/napa and buying new NGK plug wires, and shit canning the drivers side bank wires.

 

My next move would be to rule out the injectors and coils.

I'd swap the injectors from cylinders 2 & 3 (the misfiring ones) to other cylinders, taking note of which injector ends up on which cylinder. If the misfire code follows the injector to its new cylinder, you have your culprit.

If the misfire stays where it was, I'd swap the ignition coil to a new position and repeat the test.

 

Alderleet and Crainholio,

Thank you for the help. Will try and see what happens!!

Sincerely,

JJF64!!

 

Not sure where the data came from, but P0300 is for random cylinder misfire, not fuel system lean. Fuel system lean codes are in the P074X range. Just so you have the right information.

 

Well, update, changed the plug wires, cleaned off the MAF sensor, started it up and it ran really well. Took it to fill up, about 10 minutes later and it started acting up again and check engine light came back on. Don't know the code yet, but suspect it to be the same again.

Is it hard to pull the injectors? Just rebuilt a 22RE and had to take the intake manifold off to get to them.

No idea which cyclindar is missing, but it has jumped from 5 to 2 and 3, have to try them tomorrow.

Thanks.

 

With multiple random ones like that I would be looking at things such as fuel pump and fuel filter. You will be hard pressed to find a faulty injector on a random misfire by simply pulling them, if it is the injector itself. You can however check for trash in the inlet that could be blocking the fuel supply.

 

UPDATE #2
used chemtool and cleaned out throttle body, it seemed to help, but still running rough.

Error codes said cyclinders 2 and 3. So I pulled both, and it looked like it's running a little rich, black with some darker tan, but may be the chemtool going through.

Used a different coil/boot and put it in, checked gap on 2 and 3......wala!! New engine.

Started looking at the old coil/boot and found the rubber had cracked on the boot beneath the coil, about an inch long, could see the gray from the spark going out.

Hopefully fixed the problem, but wanted to say thank you for all who helped!!

JJF64

 

Congrats! Good troubleshoot and hopefully that's the end of your troubles.