Last post on Dec 04, 2008 at 9:08 PM
You are in the Speed Shop Tuning and Modification
What is this discussion about?
Nissan 350Z, Nissan 370Z, Performance Mods, Engine, Fuel System, Coupe
#26 of 45 Re: Need a little advice on what to tune up for more HP [03nissan]
Oct 09, 2007 (12:32 pm)
practice practice practice
by the way, traction is even a problem for bone-stock Zs, so I have no doubt you need better tires.
Oct 10, 2007 (11:06 pm)
my nissan misfires alot. u can hear it out the exhaust pipes. is it the spark plugs? the service engine lighted up and when the car is on 4 a while the light flashes? u can feel the car shakes alot
#28 of 45 re: [03nissan]
Oct 11, 2007 (9:51 am)
could be any number of things. if it is shaking, yeah, it sounds like you may have a fouled plug, but why is it fouled is the real question. Could be as simple as bad gas or it could be as major as a bad valve. There are just too many possibilities and not enough info. With the light on, you need to take it somewhere and get that code read, that's the only starting point.
#29 of 45 re: [qbrozen]
Oct 11, 2007 (2:48 pm)
What mods are done on the shaking 350z?
Oct 12, 2007 (5:52 pm)
i took care of the problem thank u guys for ur tips. a spark plug was touching completely like it didnt have no gap at all. it was tight closed. and that plug was a little wet with oil. why did the plug get like that. u guys think is because of my gas? or my valve because its just one. the others are fine. i know my valve cover gaskets are bad and thats why it gets wet with oil. could that be the reason 4 the plug messing up. the plugs are ngk platinum and i had them bearly for 1 month
#31 of 45 re: [03nissan]
Oct 14, 2007 (4:48 pm)
That plug probably got wet with oil because the gap was closed up, and so there was no spark in that cylinder. Plug gaps do not just close up by themselves. There is a reason that happened. Probably the most likely possibility is that someone dropped the plug when it was first being installed, and that impact closed up the gap. In that case, the cylinder never fired properly since the plugs were put in.
Another possibility is that there was a foreign object in the cylinder that hit the plug at one point. If that was the case, it has hopefully blown out through the exhaust valve by now.
The third possibility is that the wrong plug type was installed in the engine, and at least one of them was hit by the piston. Check all the plugs to see if they have the exact same part number as the one that closed up, and look for signs that the ground electrode on other plugs may have been hit. The stock NGK platinum plug is #PLFR5A-11 (stock #6240) The gap should be .044" If an NGK iridium plug was used, the part number would be LFR5AIX-11 (stock #4469).
If you check all these points and don't find any problems, considering you have a modified engine and drive it hard, there is a chance that the platinum plugs are too hot for the engine under hard driving. Platinum plugs will sometimes show less tolerance for heat than plain old nickel electrode plugs. So you might need to go to a colder plug. And, if this is the case, and you stay with the plugs you've now got, one of them may close up again in hard driving, or the insulator might break up. That could potentially do more damage to the engine than just making it miss.
With a modified engine, I'd consider going one or two heat ranges colder. One range colder in iridium would be #LFR6AIX-11 (stock #6619). Two ranges colder would be #LFR7AIX (stock #2309).
Oct 14, 2007 (10:03 pm)
thank you. it helped me alot. im going to try these procedures.. but what brand of plugs do u recomend me?
#33 of 45 re: [03nissan]
Oct 14, 2007 (10:41 pm)
If the other plugs all had the same part number as the one that closed up, and it was the part number I said was the stock recommendation, then I would go to a colder plug. You can use either an NGK iridium plug, or a silver electrode racing plug made by a company called Brisk. The Brisk will give you more power, but it is not carried in local stores, so it would have to be ordered online through briskracing.com The Brisk part number is ER14YS. And you'd have to set the gap before installing.
The NGK iridium plug is part #LFR7AIX, (stock #2309). If your local stores don't carry it, you can order it online at sparkplugs.com They are $8.00 each from that source. These plugs come set to a smaller gap than your engine needs, so their gaps will also have to be reset before installing.
Oct 15, 2007 (2:44 pm)
ngk-R laser Platinum Premium (PLFR5A-11) 6240
#35 of 45 re: [03nissan]
Oct 15, 2007 (4:38 pm)
I assume you are saying that the plug number you posted is what is now in your engine. That is the stock plug. So those plugs are now probably too hot for engine, because of the modifications you've made.
I would recommend ordering a set of Brisk ER14YS from briskracing.com
The last time I ordered from them, they sent a card that had a promo code of "LESLIE" on it. If you enter that code on the form when you order, they'll give you a free gift.