Direct injection or?

[D1dad]

Yesterday while applying wool wax to the underneath of my 21 I noticed soot/carbon on the tip and inside the tailpipe. I just turned 5k on this thing, 2.5 not the turbo version. I know these are now DI versus my 18 rogue which is not and has a spotless tailpipe at 45k. I’ve never owned a DI engine so this may certainly be normal, but in the old days meant an incorrect fuel air mixture, or worse stuck rings or valve issues. The oil level appears normal as it only has 100 miles on my 5k oil change. Although the dipstick on this thing is next to worthless as far as getting an accurate measure. Anyone else seeing carbon buildup on the new engine design or do I have a future issue in the making?

[VStar650CL]

Just about everything GDI builds up superficial carbon throughout the system, but we haven't seen anything excessive on the new Alties. With GDI's in general, when buildup problems do occur, it's usually at the valves, specifically on the backs of the intake valves. Routine de-carboning is a good idea every 30K or so.

[D1dad]

What do you suggest for decorboning? The owners manual is the typical Nissan jargon. “Oil that meets SN GF5 and Nissan doesn’t recommend fuel treatments”.
My wife’s 18 just had a slight idle fluctuation and I used a bottle of techron and it cleaned right up. Unless we are on the road we always fill up at the same marathon (top tier fuel) so I use quality oil and gas and change it regularly. The last car I had that had a dirty tailpipe was an 08 impala that burnt a half qt every few k

[VStar650CL]

My technique (and most others at our shop) is a teaspoon of ATF down any vacuum orifice with the engine warm and held at 3500~4000 RPM. The mineral oil creates a temperature differential in any caked carbon that fractures it and breaks its adhesion, letting it burn up in the cat.

[D1dad]

I just ran hpl oil which is crazy expensive to 10% on the oil monitor. Didn’t think I could do it but I did. My used oil analysis suggested I still had life left in the oil. So the direct injection in these are nowhere near what Honda or Kia’s are putting out with severe fuel dilution. In fact the fuel dilution was under 2% which is really good. It’s nice to know that these things aren’t dumping crazy amounts of fuel in the oil. Now, do I replace an almost 4 yr old oem,agm battery before an Ohio winter? Or ride it out?

[VStar650CL]

I just ran hpl oil which is crazy expensive to 10% on the oil monitor. Didn’t think I could do it but I did. My used oil analysis suggested I still had life left in the oil. So the direct injection in these are nowhere near what Honda or Kia’s are putting out with severe fuel dilution. In fact the fuel dilution was under 2% which is really good. It’s nice to know that these things aren’t dumping crazy amounts of fuel in the oil.

Part of the reason is that the gen6 Alties have both port and direct injection. It not only prevents much of the carbon buildup from typical DGI's, it also spreads out the fuel delivery, which I have to think is responsible (at least in part) for the minimal dilution. I wish Nissan would do that on all their DGI engines.

[D1dad]

That’s good to know. What’s your take on an almost 4 yr old oem battery? I only have auto parts stores to test them so I’d rather not even bother wasting my time. I usually replace a battery every 3-4 yrs regardless, but this is the 1st time I’ve had a car with agm and dam they’re expensive.

[VStar650CL]

You're actually touching on one of the great Nissan mysteries that leaves me scratching my head over their engineering department. One of the "never do this" rules about AGM batteries is to never apply a charge voltage below 13.5V, it causes internal corrosion and plate-shedding. Yet the "smart charging" systems are all demonstrably stupid about it, routinely dropping below 13V when the load is minimal. This is engineering 101 stuff, and as ticky as Nissan is about us warrantying batteries, I don't get the cavalier approach to charging. Color me baffled.

My advice? Replace it with a flooded battery and carry on.

[D1dad]

At what % of “battery health” should I replace? I bought an Ancel tester, which had good reviews and my 18 and 21 batteries are 3 and almost 4 yrs old. They’re both showing 85-95% but even after charging on my noco tender are still showing a recharge needed. The wife’s 24 is testing at 100% and dam well should. I also noticed that the Nissan batteries are enhanced flooded vs agm. Cost isn’t an issue but I don’t wanna replace it if it doesn’t need it, but also don’t wanna be stranded.

[VStar650CL]

Honestly, we see so many problems with EF batteries (both failures and diagnostic issues) that I don't recommend them to anybody. We can't even trust the DCA-8000 to properly diag them, and that tester is "dead nuts" for anything else you throw at it. My advice for testing is to use an old fashioned load test, and when you replace any Nissan battery, use a regular flooded or deep cycle flooded, not EF. Maybe somewhere down the line the battery makers will get the kinks out of the EF's, but for right now... yuck.

[D1dad]

I just priced a battery at the dealer and, yeah, no. They did offer to install for free and reprogram the car for it. Does a new battery on a 21 actually need programmed Vstar or is this more dealer BS?

[VStar650CL]

I just priced a battery at the dealer and, yeah, no. They did offer to install for free and reprogram the car for it. Does a new battery on a 21 actually need programmed Vstar or is this more dealer BS?

Big BS. I wish we could reprogram the charging parameters, but no such luck. The alternators are LIN and not PWM, so we can't even cut the PWM wire to force output like older models.