Jump to content
SAU Community

Recommended Posts

Sparking Plugs For Tastefully Modified VQ25DET

During a regular service recently, the workshop fitted new plugs - NGK PLFR6A-11 Platinums - to my NM35.

And now the engine misses on boost at anything over 5,200 rpm.

The mechanic threw away the original plugs so I can't check their heat range.

But I suspect the newly fitted 6 heat range plugs are too hot.

If you had an M35 with a set of tasteful mods such as: Hypergear SS2PU turbo, fat intake, HDi intercooler, uprated actuator, Scotty dump & front pipes, Fujitsubo exhaust, HDi EBC, Walbro fuel pump and big injectors, & GReddy Ultimate ECU, etc., making 267 of Jez's kW atw, would you run a 7 heat range plug like the NGK LFR7AIX IX Iridiums, or would you jump to an 8 heat range?

Thank you.

Would have thought 6 heat range ok ...maybe 7 at the most - pull out a plug and look at it. Whether or not its the correct plug for a VQ25 I don't know - have you checked that? Is it still gapped to 1.1mm?

Wow, thank you all!

Sorry, I should have stated: 267kw @ 5,200 rpm @ 18psi on pump 98.

I did check the older (2015) SAU Wagoneers spark plug thread.

YangLUI posted a table listing NGK Japan's recommendations for the NM35 VQ25DET:

best to normal: LFR6ARX-11P -> LFR6AIX-11P -> LFR6AIX-11 -> PLFR6A-11. (All 1.1mm gap.)

So mine are recommended for stock engines, and gapped at 1.1mm.

But further in the thread, Scotty wrote:

"Stock engine, 6 heat range is fine, so is 7. Quite often I see 5 though which is too hot.
  Modified cars LFR7, or 8 if you have the coin for HKS tax."

And further, when replying to a question about Nismo RN020-7 plugs (NGK part no LFR7AIX-P gap 0.8-0.9mm), Scotty wrote:

"Those Nismo plugs are a 7 heat range, no point getting those [Nismo's] when the LFR7's are half the price.
  Gap doesn't matter in this case, as they will still work at 4mm gap thanks to our coils."

So that's why I think maybe the 6's are too hot.

Daleo's magic table (where did you get that!?!) indicates I should be running at least NGK 2309 LFR7AIX IX Iridium Plugs (which have an 0.8mm gap).

I'll get some.

Thank you all very much. What an absolute pearl this forum is!

I'm off to donate.

  • Like 2
  • 9 months later...

Just to finish this off, while fitting new plugs, Denso IKH24 (8 on the NGK Heat Range table,) we found the real problem is a left rear plug seal.

Oil had seeped down the plug.

The NM35DET rocker cover has the plug seals manufactured into it, dammit.

With new plugs, it's temporarily running smooth, while I try to locate a left rocker cover (anyone got one?).

For the VQ25DET, the rocker cover part numbers are:

RIGHT SIDE ROCKER COVER

maker             nissan
parts code     13264
parts no         13264-AQ801
parts name    COVER ASSEMBLY,VALVE ROCKER

Vehicle                   period                     model     fig
CEDRIC/GLORIA 1999/06-2004/10      Y34     111E
CIMA                      2001/01-2010/08    F50     111A
STAGEA                2001/10-2007/07      M35    111B

LEFT SIDE ROCKER COVER

maker            nissan
parts code    13264+A
parts no        13264-AL611
parts name    COVER ASSEMBLY,VALVE ROCKER

Vehicle                 period                         model     fig
CEDRIC/GLORIA  1999/06-2004/10     Y34     111D
CIMA                      2001/01-2010/08     F50     111A
SKYLINE                2001/06-2007/06     V35     111B
STAGEA                2001/10-2007/07      M35     111B

http://jp-carparts.com/nissan/partlist.php?maker=nissan&type=153&cartype=12&fig=111&page=8

Thanks for everyone's great help. At least I have the right plugs now! 

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...