Replaced the Spark Plugs now engine diesels

[svard75]

Hello to everyone.

Just bought the 06 M35x with 86000kms and began running through the maintenance plans. Changed the AT fluid, Coolant Flush, all 4 brakes changed and sanded painted the calipers silver, engine air filter, cabin air filter and got to spark plugs. Changed them myself after much struggling to inch my fat fingers through all the wiring harnesses to remove the coil packs and plugs. Went with the Champion Double Platinum plugs (See below for specs). Put everything together and fired it up. Engine diesels like crazy. I fear one of the plugs either are not working or a coil pack may be broken. Worst case a wire from the harness broke! Out of the box they were gapped 0.045 so I regapped to 0.043 as specs list.

What do you guys think could be causing this? It's still under warranty so I did take it in.

Spark Plug Specs14mm Thread, 25.4mm (1") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor','2','1')">Resistor, Platinum Tipped Ground Electrode and Platinum Tipped Center Electrode, Projected Core Nose, Heat Range 12

[GJEMD]

At 86,000 plug wires are due. I also would have gone back stock with NGK PLFR5A-11 plugs

[MinisterofDOOM]

No such thing as plug wires on modern coil-on-plug distributorless ignition systems.

I definitely agree on going with stock NGK, though. You may well get better results with them than the champions.

[300freekzx]

Champions are crap get the NGK

[svard75]

Thanks so far. Noted. Still didn't answer my question though.

Even if the plugs were crap it shouldn't diesel. I wonder if it's due to a coil pack going bad during the replacement. I was very careful when taking everything appart and put it all back together carefully too so not sure what the issue is. I already heard from the dealership they said my cat is melted.

[SteveTheTech]

msvara- Welcome to Nico, great start with a really good question.

I have to agree with the guys above, inferior plugs and or a poor connection at the coil connector.

Infiniti has used coil on plug designs since the 90Q, the only car that didn't use them was the G20 and the Qx4(pre-6/00). Just a side note.

The reason you may be experience either detonating early or late in the combustion cycle. Is one of the constants for normal operation has changed and the computer does not know what is wrong. If the CEL has come on of the car is missing check the connectors too. If the computer detects a miss(detected at the CKP, crank position sensor), incomplete burn (O2 reading vs. injector pulse), or varied Knock sensor signal, it will do anything it can to return the engine to stoichometric operation. Everything is adjustable from injector pulse width, to intake timing but if a constant such as spark plug resistance and discharge pulse change then the computer will not be able to adjust enough to accommodate the new plugs and it will freak out. Champions and Auto-lite are the worse thing you can put in any Nissan. Get them out get some OE NGKs in there and see what happens.

[ken in az]

1st - If a coil pack went bad then you would have a misfire, not a dieseling condition

2nd - your reach on that plug is too long, it should be 11.2mm(7/16")

3rd - your heat range is too hot, it should be a 10 range in champion

4th - only ever use NGK products in Nissan/infiniti applications.

Of all 4 of the reasons posted above, I bet the main contributor of your dieseling is the heat range being too hot.

Change out to a platinum or iridium ngk plug and your problems should go away.

BTW - who sourced that plug for you?

[MinisterofDOOM]

I'm so used to backward NGK heat range that I didn't notice that. The heat range may well be a factor as well. If anything, in hot humid summer, you want to move to a cooler plug. Moving to a hotter plug during the summer could cause your symptoms.

Infiniti has used coil on plug designs since the 90Q, the only car that didn't use them was the G20 and the Qx4(pre-6/00). Just a side note.

Don't forget the VG30E-powered M30.

[ken in az]

Don't forget the VG30E-powered M30.

The most under-rated engine of all time! I love that engine!!

[fiveliterbeater]

The most under-rated engine of all time! I love that engine!!

you think so? that motor also came in the 89-91 SE maxima and 89-94 GXE. it was a decent motor. i always thought the VG30DE in the 300ZX was sorta underrrated.

[svard75]

Wow lots of excellent info here. Thank you all for the advice. I was sourced these plugs from Canadian Tire (AKA Crappy Tire) now I know why they call it that!

So because the reach is longer it's possible that my piston could have mashed the electrodes and shorted the plug out completely. NGK's were in there when I removed them but I didn't do a visual between the old and new. Why would they source the wrong plugs? Even their website suggests them!!!http://www.championsparkplugs....31822

[ken in az]

Wow lots of excellent info here. Thank you all for the advice. I was sourced these plugs from Canadian Tire (AKA Crappy Tire) now I know why they call it that!

So because the reach is longer it's possible that my piston could have mashed the electrodes and shorted the plug out completely. NGK's were in there when I removed them but I didn't do a visual between the old and new. Why would they source the wrong plugs? Even their website suggests them!!!http://www.championsparkplugs....31822

If you use the part number for the regular plug and use the champion part number reference guide

you'll see that the specs they list on the left side of the page do not match the part number listed for the plug part number for the conventional plug "REC10YC4"

[ken in az]

Here is the NGK numbering system - OEM application is PLFR5A-11 plugs

[MinisterofDOOM]

Why would they source the wrong plugs? Even their website suggests them!!!http://www.championsparkplugs....31822

A lot of auto parts stores will recommend various "compatible" brands in addition to OEM, and most parts stores are used to customers preferring the cheapest option, so they'll start there first. I always have to fight with Autozone around here to sell me NGKs instead of Bosch for my Maxima. It's just the way their computer listings work. Technically those Champions work, but the NGKs are what the car was designed for, and Nissan engines have historically demonstrated a definite preference for NGK.

The most under-rated engine of all time! I love that engine!!

Agreed. I have a VG30E in my '93 Max and absolutely love that motor.

[ken in az]

you think so? that motor also came in the 89-91 SE maxima and 89-94 GXE. it was a decent motor. i always thought the VG30DE in the 300ZX was sorta underrrated.

Yeah, that engine went in almost every nissan built. Maxima, Frontier, Xterra, 300zx.

The vg33e is near the same engine just more displacement. The vg30dett is the twin turbo version with dual overhead cams. the only problem with the vg30dett engine was the heads were so big and it was so compact in the Z engine bay that everyone hates working on it. that and heat kills the wiring harness.

I don't know of too many engines you can buy for less than $400 out of the junk yard and run 20+ psi of boost making over 450rwhp with reliability. JWT has the setup on the ecu's and you can use all sorts of custom rom programs to run a stand alone ecu setup. I've seen 700rwhp out of one straght from the junkyard - albeit it lasted for 3 1/4mi runs, but them being so cheap it is almost worth it!

[svard75]

Thanks for all your advice duly noted.

Someone hit me with a hammer! I crossed cylinders 4 and 6!? I have no idea how that happened but it did and it cost me lots of money. A catalytic converter cost me $1039 plus the labor and diagnostics etc etc totaling $2000!

That's what you can expect to pay out if you change your spark plugs and not be careful enough.

I did have them replace the Champions with OEM NGK's so I'm back to norm again.

Cheers everyone!

[mjlyn]

Ouch!!! That hurts!!