wizard

My J-Spec 350z has been playing up recently. I nailed the car last night in 2nd and 3rd gear with the SP 100 shot progressive and the car went into 'limp mode', and I basically had to pull over to the side and switch off the engine for a few seconds before restarting. VDC off, SLIP, Oil pressure light come on and stay on before restarting when they went off. This has been happening for the last few months.

Now the car has not been mapped to run this nitrous but has not given me any issues since I got it installed (July 2008 -50 shot) and progressive 100shot for over a year. The other thing is that the issue used to occur sometimes WITHOUT nitrous (N/A) on heavy load. This is recently stopped. My tuner recently installed a new throttle body in the car, but the issue is still there when nitrous is switched on.

Ok this is the stupid part, since going from a 50 to a 100 shot, I did not change the sparkplugs and he thinks that it could be related and wants to dyno the car to replicate the problem but only after changing the plugs. I think the car is still running the stock plug which are:

plfr5a11 (1.1 gap size) - platinum - heat range 5

I know platinums are a big no no for nitrous.

I was thinking of going one step colder iridium (6) to ngklfr6ax-11 (1.1 gap size). What would you guys recommend to change them to? - Considering 99% of the time the engine is not inhaling nitrous. Or 2 steps colder with 0.7 gap?

Any advice on spark plug recommendations from Nitrous users would be appreciated.

Thanks

ArcticT

On a 100 shot I don't think there is any reason to go two steps colder. And it's never a bad idea to get the car on a dyno if you are spraying.

drivessidewayz

iTrader: (4)

I think a lot of people run...LFR6A11 copper NGKs. (pretty sure that's the right number...)

wizard

Yep, that's the one I was going to go for but the problem is the 1.1mm gap. They can be re-sized and reduced but i'd prefer not to do that.

Managed to find the 'best' one. One step colder (6) and at 0.8 gap. Quite expensive though. It's the Denso VKH20Y.

Will update you guys on whether that fixes the problem.

Sparks03Max

iTrader: (1)

I would go with side gapped NGK copper plugs over any other brand. I went with those (LFR6A11) with nitrous and had no issues.

wizard

Spoke to a friend of mine that is running denso's in his 350z N/A race car and he said they've never caused him any issues. Smaller gap should mean less likely for misfire and hopefully causing this limp mode issue?

Anyway, I've brought them... Was going to get the ones you mention, which were cheaper, but the nitrous boys said I should be re-gapping them which I didn't feel comfortable doing.

wizard

Ok so this did not resolve the issue. Changed oil, filter, and plugs... no avail.

Any suggestions?

absurdparadox

iTrader: (1)

I'm still new to Z's and anything beyond OBD1 ECUs in general. Having said that, I think the first thing to do would be to come up with a list of what will put the car into limp mode -- the biggest question is, will high knock counts do it?

What plugs did you get? Plug gapping is easy, so don't even sweat it.

Dhoffman

I bought Lfr6a11 and gapped at .o43. No problem so far except the the left bank seems to be running rich. I noticed more black suet comming out of the exhaust
Is it possible that one bank can run richer than the other?

BakaN20

iTrader: (26)

Driver side runs leaner, air doesn't distribute evenly. Thats why most people put their o2 sensor on the driver side.

Dhoffman

That’s what I suspected. Thanks for the responds. Is there a plenum that will distribute air more evenly?

iideadeyeii

iTrader: (6)

I believe a plenum spacer addresses this problem maybe angled? Not 100% positive as I have the Kinetix V+ plenum