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Old 04-19-2010, 02:16 PM   #1
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Default MAF Circuit high

I keep getting a check engine light but can figure out why (MAF Circuit high) on a 2003 miata turbo. Doesnt appear to be ECU replated.

I notice that my car will some times go lean but when i try again i cant get it to do it to recreate the problem. This usually happens above 5K rpms no boost.

Also in boost I will have an AFR close to 11.1 but the car will suddenly buck and back fire as if I hit a hard rev limiter. Its random but always happens above 5K rpm.

I'm at a total loss. But any time it happens I immediately get a CEL.

What i have done that solved a large portion of this issues but did not eliminate it completely.
Cleaned the MAF
Cleaned out the intake manifold
Replaced plugs and wires
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Old 04-20-2010, 03:59 PM   #2
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You are getting a high MAF circuit because you have hit 5V on the
MAF output somewhere, sometime. Usually only happens if you are running more than 12 psi though.
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Old 04-20-2010, 04:47 PM   #3
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Thank you Stephanie,

So the Miata does have a MAF limit? I didn't think of it because I have hit 15 psi before in an accidental boost spike with out any problem. But i was running the xede that lowers the MAF signal. I have read that I didn't need a MAF clamp in a Miata but I will give it a try anyway.

Right now I have an occasional rare spike to 12psi, I need to make some adjustments to my boost controller. I might also need to check for boost leaks but dont have the equipment to do it at the moment.
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