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RB 25 Flat Spot

Guest Robo's

By Guest Robo's,
in Engines & Forced Induction

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Guest Robo's

Guest Robo's

Posted
Posted

Ok, after i tuned my R33, and now driving around for a few weeks i've found im getting a flat spot in the power curve. It has exceptional strong mid range and top end (6000-7000) but i notice ive got a dead spot around the 5,000 mark. Like mid range is strong, then it goes flat, and then strong to redline. Overall im kicking out around 210rwkw which feels strong, but i feel if i can get that flatness out i would be happier even more. Im only tuning it with a SAFC, i havent started playing with timing yet although i reckon im on the mark as it used to ping with the stock cooler, not so with the FMIC.

Any thoughts?

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Redbaboon Collaborator

Redbaboon

Posted
Posted

The best way is to get it properly checked on a dyno, and the tuner can enrich/lean out your mixture with the S-AFC in this range, depending what its doing (the only way to know is to get it properly checked).

Another cheaters way is to undo the bolts to the crank angle sensor and turn the housing a few degrees (so you can just see where the old bolt mark was) and tighten. This advances the timing slightly, it gave me an extra 12rwkw when I did this on the dyno.

Good luck.

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https://www.sau.com.au/forums/topic/41419-rb-25-flat-spot/#findComment-850811
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Steve Grand Master

Steve

Posted
Posted

Have you checked your airflow meter reading on the AFC? Mine hit 5.115V at around 4.5-5k rpm with 200rwkw, which wasnt a problem until I got a cold day. Net result was detonation on colder days - perhaps you are leaning out and the ecu has pulled some timing.

If it was a one off occurence, it is possible the ecu has pulled some timing in that range - how lucky do you feel:)

Best bet is put the car on a dyno where they can check. Even if a tune was done 2 weeks ago, a cold day and you are in trouble when you tune on the edge.

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Guest Robo's

Guest Robo's

Posted
Posted

She is not pinging at all now, i havent heard it ping since installing the FMIC, which makes me think some more timing could go in. But with the stock cooler, i used to get some ping up high and i havent adjusted the timing at all, just the A/F ratios. A/F ratios are as good as we can get with the SAFC, between low 11's and high 11's. We can never get A/F ratios to be nice and steady due to the limitations of the SAFC, but we are trying hard.

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