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
#37 of 45 my 350z is letting my nissan pride down
Nov 05, 2007 (10:35 pm)
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 ass and i dont get it why?
#38 of 45 Re: my 350z is letting my nissan pride down [03nissan]
Nov 05, 2007 (11:50 pm)
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.
#39 of 45 Re: my 350z is letting my nissan pride down [03nissan]
Nov 06, 2007 (8:41 am)
just return your car to stock. that's my best advice.
#40 of 45 Re: my 350z is letting my nissan pride down [zaken1]
Nov 06, 2007 (2:17 pm)
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.
#41 of 45 Re: my 350z is letting my nissan pride down [zaken1]
Nov 10, 2007 (12:46 am)
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
#42 of 45 Re: my 350z is letting my nissan pride down [03nissan]
Nov 10, 2007 (11:38 am)
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.
#43 of 45 Re: my 350z is letting my nissan pride down [zaken1]
Nov 10, 2007 (2:41 pm)
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.
#44 of 45 Re: my 350z is letting my nissan pride down [zaken1]
Nov 11, 2007 (12:55 pm)
thanks 4 looking up on that for me. i appreciate it and i will keep that in mind