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Nissan 350Z and 370Z engine and exterior tuneups

2

Comments

  • paisanpaisan Posts: 21,181
    Tires are definitely your problem, probably reaction time too but tires you can fix easily.

    Anytime you add more power you should always upgrade tires and brakes accordingly. If you can't get the power to the ground, you won't go fast.

    I'd suggest a set of BFG KDxxx tires. Very good at the drag strip from what I've heard. Also might try some dedicated 1/4 mile tires as well like Hoosiers or some drage radials.

    -mike
  • and how can i get good in reaction b cuz i admit i do pretty bad
  • qbrozenqbrozen Posts: 17,147
    practice practice practice

    by the way, traction is even a problem for bone-stock Zs, so I have no doubt you need better tires.

    '13 Stang GT; '86 Benz 300E; '98 Volvo S70; '12 Leaf; '14 Town&Country

  • 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
  • qbrozenqbrozen Posts: 17,147
    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.

    '13 Stang GT; '86 Benz 300E; '98 Volvo S70; '12 Leaf; '14 Town&Country

  • paisanpaisan Posts: 21,181
    What mods are done on the shaking 350z?

    -mike
  • 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
  • zaken1zaken1 Posts: 556
    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).
  • thank you. it helped me alot. im going to try these procedures.. but what brand of plugs do u recomend me?
  • zaken1zaken1 Posts: 556
    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.
  • ngk-R laser Platinum Premium (PLFR5A-11) 6240
  • zaken1zaken1 Posts: 556
    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.
  • thank u very much i will order brisk er14ys and will keep in contact a/s/a/p
  • i fixed my car. headers, exhaust, cold air intake. high perf. clutch. it worked badass. NOW!! my o-2 sensors are low my mass air flow sensor is damaged it turned on my cel on. my car doesnt feel powerful any more. i step on it and i dont feel what i used to. when i change gears it doesnt kick me bak no more.(well sometimes it does.) my 1/4 mile run is worse than when i was st0ck. why is that can anybody help me out? is it because of my mass air flow sensor? or my o-2 sensors or what can i do to it? i love my z and i hate to give it up. stock z's kick my [non-permissible content removed] and i dont get it why?
  • zaken1zaken1 Posts: 556
    The last time you posted here, you said you would order a set of Brisk plugs. So did you get them, and what happened?

    Besides the fact that your stock plugs are too hot, the low O2 sensor readings mean that your engine is running too lean. The headers, exhaust, and cold air intake all lean out the air/fuel ratio. When you make changes like that, you then have to richen up the fuel mixture in order to get the potential power gains those modifications can produce. And the way to richen the mixture is by having a shop that does dyno tuning tweak your computer to correct the too lean fuel mixture. Some shops have the knowledge and skill to do that, but many others don't. So find out beforehand from professional racers about which shops are good at that very specialized type of work. And it will cost you some bucks, but there's no way to modify an engine and get results without correcting the fuel mixture, period.

    Many times, people make very good modifications to their engines, but then find they have less power than they did before. This frequently means that the fuel mixture has gone off because of the modifications. But when you take that badly running car and straighten out the mixture, it becomes a whole different type of animal.
  • qbrozenqbrozen Posts: 17,147
    just return your car to stock. that's my best advice.

    '13 Stang GT; '86 Benz 300E; '98 Volvo S70; '12 Leaf; '14 Town&Country

  • paisanpaisan Posts: 21,181
    I have to agree with Zaken. First you need to fix your Mass Air Flow Sensor and O2 sensor in order to do anything. Then you need to get it to a dyno-tuner who can tune it. This will run you anywhere from $400-1000 depending on who is doing the tuning, where you live, etc. That is the only way to take advantage of the bolt-on parts you put in. While you are at it, once you increase power you need to modify your brakes, suspension and tires to handle the new-found power, this is the #1 way to wreck a nicely tuned car is to plow into something because the car couldn't stick or stop well.

    -mike
  • yes sir. i got the iridium brisks. i have more power and my car is doing ok.now my problem is the o2 sensors. i was told exactly the same thing about my gas being too lean. that is why now i trust my mechanic because im also hearing it from you. do u think i also need to replace my o2 sensors or i should only get the gas tuning? my mechanic says my sensors are slow and that they should be between .400 and .800 but when he did the tests they were .150 and lower. what is better 4 my ride a reflash or a gas management programmer
  • zaken1zaken1 Posts: 556
    I'm glad to hear you got the cold plugs! It sounds to me like your O2 sensors are probably not broken. The low and slow readings are to be expected, when your mixture is too lean. That just means the sensors are doing their job. When the mixture is corrected, the sensors will read faster and the levels will be higher.

    A stock reflash would just reinstall the original specs into the computer, and that wouldn't change your fuel mixture. But maybe you were referring to reflashing the computer with a higher performance map for the fuel mixture. I don't know if that is an available option. If there is a reflash of a modified fuel map out there, it would cost less to install than a fuel management programmer. But the fuel management programmer would allow you to adjust the mixture to get the best performance, while the reflash would lock you into whatever mixture settings were written into it. If the reflash specs were intended for an engine with just bolt on modifications, like you have, it would probably work OK; but if it was intended for a supercharged or all out race motor, the mixture wouldn't be right for your needs.
  • zaken1zaken1 Posts: 556
    After writing the note above, I did some checking around, and found that there is now a fuel and ignition controller made for your car by AEM, which is made to connect to the car's stock computer. It can change the injection pulse width by infinitely variable steps, up to an 100% increase. And that should enable precise setting of as much additional fuel as you'd ever need! It also allows retuning if you make future modifications to the engine. Because this controller works in combination with the stock computer, it is much less expensive than a stand alone unit. It will probably need to be initially programmed by connecting it to a laptop or desktop PC. AEM developed this part for the 350Z, so there is no question about it working well. The current ones may need to be hard wired into the vehicle. They're talking about making it a direct plug in system later on.

    Summit Racing has this unit in stock under part number AVM-30-1910, and sells them for $397.95.
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