SR - Need Tuning Help

A place to discuss the systems and methods of tuning Nissan engines.
Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

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Ok so I got my Apexi SAFC II wired in and it works great but I cant figure out what my car is doing.

SymptomsThought the car was getting fuel cut so I upped the fuel level 12% over the 1200-4000RPM range all the way to redline. The curve is smooth not just straight up.The car since then has acted like it had been but more.It gets a popping/ Back Fire noise out of the exhaust when I punch the gas and build full boost. 12 PSI.I dont get any knock so its not pre detonation.

Would I be running rich?Do I need to regap my plugs?Do I need colder or hotter plugs?Do I need a grounding kit cause of weak spark?

I need to know what to do because Im out of ideas and Im afraid to lower the fuel map in fear of hurting the motor by running to lean. SUggestions?


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slamdbusa
Posts: 112
Joined: Sun Jan 22, 2006 9:26 am
Car: 240sx, ex-ka-t, now sr

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what sized injectors are you runing?

Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

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The Stock SR Redtop injectors. My Buddy runs the same injectors on 15 PSI so I dont think thats the problem.

I believe stock is like 370 cc or something.

240guyNY
Posts: 117
Joined: Thu Sep 01, 2005 4:42 pm

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15 psi is a waste on stock t25, might as well turn it down to 14 and save some heat and turbo life. and you'll barely notice any decrease in power if any.

Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

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Im not running 15. Im running about 12 psi....

I still need an answer though....

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teddy
Posts: 2013
Joined: Tue Dec 07, 2004 11:16 am
Car: Saab Turbo and MR2

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Is the car bogging pretty bad when you get on it? Shooting out black smoke at all? What heat range plugs are you using...

Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

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when I punch it and it makes the popping/backfire noise out of the exhaust it losses all pull/power but then regains it until it pops/backfires again.

I think Im running to rich. What would be a safe amount to drop the fuel level? Also will the SR ECU protect me from running it to lean?

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Tartan
Posts: 434
Joined: Thu Feb 27, 2003 8:00 pm
Car: 89 240sx

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Maybe you should bring the fuel level back to zero. If you are running stock injectors then you really dont have to touch the fuel levels unless you are tuning the car. Adding more fuel to a rich mixture will only make things worse. Are you running a catalytic convertor? Test pipes and rich exhaust causes lots of popping in the exhaust. More power is made with a leaner mixture...to an extent. How's the wiring on the mass air flow sensor? A bad reading could cause your car to run rich too.

Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

Post

I figured a few things out while testing my car.

A. Boost gauge is broken (off by 4 PSI) So I turned it down to what I think is 10-12 PSI now and I am going to buy a new Boost Gauge Soon

B. The car is running rich cause you can smell the gas

C. The MAF seems to be fine. No irregular problems other than a slight engine idle flux at cold start but goes away quickly after the first slight rev on the motor.

I have noticed a slight not knock but well I dont know how to exsplain it. It only does it on cold start when the engine first revs at start to 1200 rpms.

How low should I go with my fuel level on the SAFC? 5 or 10% or more? O tune slowly till the popping subsides?

S13FX
Posts: 2505
Joined: Sat Apr 30, 2005 10:59 am
Car: '69 l20b Dimeski :)

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or if you have the money, you can get a wideband and check your AFR's and be 100% sure

Blown240sx
Posts: 1963
Joined: Thu Apr 21, 2005 3:20 pm
Car: 1996 240sx

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there is the problem lol Im in college so money isnt an option right now lol


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