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Old 06-17-2014, 11:09 PM   #1
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Default Miata turbo sacf lean at high rpm

Hi, this is my first post. im new to the Miata turbo scene, Also i research before posting. I hoping someone have any experience withthis problem that can give me advice or help me out.
I have a 1990 Miata 1.6 turbo with Apexi safc2. The car lean out (16-17.1) at 5000-7k rpm full boost 10 PSI, the safc doesnt seem to have any effect on the ECU at that point, but it tunes the Lo setting just fine.
Mod on my miata
MHI 14b
AEM wideband and boost gauge
NA 1.8 injectors remanufacter
Walbro 190lph with new fuel filter
Yonaka exhaust 2.5
NGK bk7re gap .30
SAFC 2- setting Lo-10%/Hi-30%
Could it be timming or the stock FPR?
Theres not alot of info on Miata and SAFC. Thank in advance.
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Old 06-18-2014, 11:48 AM   #2
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If you're using NA 1.8 injectors and the stock fuel pressure, you're lucky it's not leaning out well below 10 psi. That's not going to flow enough fuel to support what the engine needs.
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Old 06-18-2014, 12:16 PM   #3
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You know what an SAFC does right? It just holds the injectors open for a longer time each cycle. If your injectors are already continuously open at 5000rpm, you're gonna have a bad time.

Turn it down to 5psi and start saving for a MS and some RX8 injectors.
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Old 06-18-2014, 12:55 PM   #4
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Thanks a lot guy, so Should I get the 1.8 fpr or adjustable aftermarket?
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Old 06-18-2014, 01:01 PM   #5
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Get the Megasquirt version. All the others are pretty much just band-aids. Sure, they'll allow you to run some boost, but not efficiently, not for very long, and not very much.
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Old 06-18-2014, 01:05 PM   #6
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I can't turn down boost the 14b has internal wastegate. I've been considering MS, but some people say it's a pain to tune for armature?
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Old 06-18-2014, 01:07 PM   #7
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Who told you that? Load the basemap, hit auto tune, drive away happy. Autotuning will get you most of the way there, but you'll need a dyno session to run ALLOFIT.

Besides, tuning a running engine is better/easier than rebuilding the blown one which you are soon to have.
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Old 06-18-2014, 01:07 PM   #8
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Quote:
Originally Posted by Blue_miata View Post
I can't turn down boost the 14b has internal wastegate. I've been considering MS, but some people say it's a pain to tune for armature?


this thread is headed for eggplant
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Old 06-18-2014, 01:12 PM   #9
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So is a reliable turbo Miata tune with safc really a pipe dream? I got s14 turbo with safc for 6 years now with zero problem.
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Old 06-18-2014, 01:14 PM   #10
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reliable and safc shouldn't be in the same sentence
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Old 06-18-2014, 01:21 PM   #11
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Quote:
Originally Posted by Blue_miata View Post
So is a reliable turbo Miata tune with safc really a pipe dream? I got s14 turbo with safc for 6 years now with zero problem.
Is your S14 a Miata?
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Old 06-18-2014, 01:25 PM   #12
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his 14B is a S14 running a miataforty at 1.8 tan top SAFC69
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Old 06-18-2014, 01:25 PM   #13
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Got it. I must have misread the original post.
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Old 06-18-2014, 01:35 PM   #14
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Quote:
Originally Posted by Blue_miata View Post
So is a reliable turbo Miata tune with safc really a pipe dream? I got s14 turbo with safc for 6 years now with zero problem.
Incorrect. It's been running dangerously lean above 5000rpm for 6 years. You can't make a 265cc injector flow 400cc no matter how many SAFCs you hook up to it.
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Old 06-18-2014, 01:44 PM   #15
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The S14 came with a turbo, so the Nissan ECU had fuel and timing rates programmed into it. The Miata does not. It has no idea whatsoever what to do above 100Kpa and you are simply tricking the injectors to stay open. Your fuel rates, ignition timing are not tuned and you will destroy your motor in short time.
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Old 06-18-2014, 01:48 PM   #16
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Alright, Thanks alot guys. Im just gonna save up to buy a MS.
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Old 06-18-2014, 01:50 PM   #17
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Best idea ever.

You won't regret it.
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Old 06-18-2014, 02:39 PM   #18
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What you gotta do is use vice grips to clamp the fuel line to increase the fuel pressure at high rpms.
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Old 06-18-2014, 03:48 PM   #19
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one last question. any mods i should be considering? or im set with these + MS.
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Old 06-18-2014, 04:11 PM   #20
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RX-8 injectors, but that should do it for getting you boosting safely and reliably.
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