2004 V70 T Seems NGK IX Iridium Spark Plugs Caused/contribute to CEM Codes Limp Mode Topic is solved

[cn90]

Maybe your NGK Ir was counterfeit? Or you did not check the gap before installation.

I have NGK Ir in:
- 1998 BMW 528i for 10 yr.
- 2006 BMW X5 for 5 yr.
- 2004 Volvo XC90 2.5T for 5 yr (not 3 yr ad mentioned above).

I only use NGK Ir now.

PS: can you post a few photos of your NGK?

[dono]

I would love to see what happens if you reinstalled the NGKs again But that is asking a bit for my curiosity.

Honestly Id be curious too - they are still in the door storage driver's side barely used. The initial results were so traumatic though I doubt Ill ever run that experiment (maybe one day before the tow truck delivers her to her final reward at the crusher). Those were some very nasty codes and God only knows what was going on with my computers.

Im a rational person and like many here its beyond me how the NGK's could cause such problems for me and work great for others. Software perhaps, electrical systems particular to my vehicle (maybe there is a none OEM electrical part installed before my time problems; (Im second owner) . Maybe my CEM is sickly and couldnt stand a minor variation in voltage. One thing is for sure those profound problems with the vehicle went away the minute I changed out the NGK's and have not returned in 1,000 miles of mostly city driving. I dont think Ill put her in Tilt mode again to see.

[dono]

Maybe your NGK Ir was counterfeit? Or you did not check the gap before installation.

I have NGJ Ir in:
- 1998 BMW 528i for 10 yr.
- 2006 BMW X5 for 5 yr.
- 2004 Volvo XC90 2.5T for 5 yr (not 3 yr ad mentioned above).

I only use NGK Ir now.

PS: can you post a few photos of your NGK?

NGK (6418) BKR6EIX Iridium IX Spark Plug bought them at AutoZone. Ill see about a picture. My understanding is you arent supposed to adjust the gap on iridium (or platinum) plugs due to the fragile tips so I never thought to check the gap on them. Ill double check that too. I do know there are 2 lengths of NGK's so I checked and double checked by VIN when I purchased the plugs.

[cn90]

Here is how to spot counterfeit NGK:

https://www.driven2automotive.com/blog/ ... gust-2017/

PS: Do a google search "NGK Iridium Counterfeit" and you will see quite a few articles written on this subject.

[abscate]

If they are boxed , rather than blister packed, it it possible they were “ return counterfeit” , especially from a local parts store.

Buy expensive plugs local

Buy cheap plugs

Install expensive plugs.

Rebox cheap plugs in expensive box and return for cash.

The evil men do....

[dono]

Here is how to spot counterfeit NGK:

https://www.driven2automotive.com/blog/ ... gust-2017/

PS: Do a google search "NGK Iridium Counterfeit" and you will see quite a few articles written on this subject.

Thanks for the link - mine appear to be authentic based on the article parameters...

[EngineeringBloke]

I had NGK iridiums for a while (2 years, 15,000 miles) and then switched back to Volvo plugs while I chase down my low MPG. The NGKs were gapped at about .030" from the package. For a turbo, the air pressure is higher and so there is more resistance to the spark and hence the gap must be smaller - .028". I did regap the NGKs ground pin. It was tough, but the main risk is if you close the gap too much, then you have to open the gap and MUST avoid bending/touching the very fragile and thin, center electrode.

I really don't think there was a problem my NGKs.

[dono]

Update: Well its not Just the plugs - car threw DTC 928C ECU communication error few days ago with the ABS light and limp mode again. This on the Bosch plugs that worked fine for 1k miles. I suspect failing CEM or ECU plus NGK's (that possibly were just enough out of OEM spec) caused constant problem with what is now intermittent problem with the Bosch plugs. Still this was a constant problem rendering the car un=driveable with the NGK's. Hope its just the ECU.

[jimmy57]

I have had plugs with wide gap cause issues on one Volvo and on several other makes. The simplest issue was that the engines had misfires. The other issues included network modules going offline with communication codes. The oddest one was an Escape with dimly flashing charge light and gauges repeatedly going off and then coming back on with full sweep needle tests.
If the secondary winding builds much larger voltage for ionization for spark discharge then the primary winding (low voltage,12V) winding can get a much much higher induced ripple voltage. The primary winding is common to the whole 12V+ side of the electrical system of the vehicle. There can also be secondary to primary arcing but that usually gives misfires.
I have installed several sets of Iridium plugs in Volvos with gap at correct dimension and have not had issues.

[abscate]

You could probably also diagnose that with a roll off filter on the primary side, upstream of the coils, to prevent ripple from coming back through.

Time to break out my Horowitz and Hill..