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Old 09-04-2006, 11:26 PM   #1
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I have a 90 Miata with 44,000mi. I have had the Greddy Turbo base kit (nothing else) on for about 3000mi. I am disappointed with it, not because of the power but because of drivability. It seems like I have to be very careful on how hard I step on the gas. If I step on it too hard too soon even above 4000 rpms it feels like something is holding it back. If I step on it lightly the turbo will kick in but I have to be very careful not to give it too much gas or it seems to bog down.
I do not need more power, I would like better drivability what do I need to do so that I can have better drivability without spending a lot of money?

Thanks for any help
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Old 09-04-2006, 11:50 PM   #2
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Bogging down? Sounds like it really has issues outside of the actual turbo system. One of the biggest restrictions with my system was my plugs/wires were shot and that was bogging me down for the longest time. Whats your timing set at?
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Old 09-04-2006, 11:57 PM   #3
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Maybe "bog down" is too strong of a word, it just accelerates a lot better and I can feel the turbo kick in if I do not give it too much gas too soon. The plugs and wires are only about 10,000 mi old, I have had the car since it was new and it always ran great. I do not remember what the timming was set at, I will check on that however the timming should be correct.
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Old 09-05-2006, 12:55 AM   #4
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I also strugled with this for a long time. I think the biggest improvments you can make in the "feel" of it without spending a whole lot would be a bipes and olderguys o2 clamp.
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Old 09-05-2006, 10:00 AM   #5
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check your fuel lines to the FMU. Are you sure they arent backwards? Clamping off your fuel would surely hold you back.
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Old 09-05-2006, 10:42 AM   #6
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snowsurfer is right. when i had mine, it felt smoother and stronger at part throttle. i think at WOT, the engine is overwhelmed with fuel and it doesn't feel as strong.
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Old 09-05-2006, 11:25 AM   #7
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I've been dumping in WAY too much fuel. I'm talking 10:1-9:1. It still pulls like a damn banshee at WOT. If his FMU lines are incorrect he might be clamping off fuel as his boost rises. An o2 clamp is a great device for boost transition, but his problem seems to have the tell-tale signs of a improperly plumbed FMU. But then I could be wrong.
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Old 09-05-2006, 11:43 PM   #8
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One of the cheapest (but not necessarily cheap) troubleshooting steps you can take isto replace the plugs and wires. The Miata is extremely susceptible to plug wire failure due to the nature of its ignition system. 10K miles is way too long on a single set of wires (YMMMV). The Miata fires on all-four cylinders, even when NOT on the compression stroke for that cylinder. This leads to early expriation of the wires, even before adding boost to the mix.
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Old 09-05-2006, 11:56 PM   #9
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Thanks for the info I will change the plugs and wires, does anyone have a picture of the fuel lines to the FMU so I can see if they are indeed backward? Would getting the o2 clamp help even if I did not get a bipes right now?
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Old 09-06-2006, 12:17 AM   #10
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I should also add that when I first installed my GReddy setup (at stock boost levels), I used to get some bog under heavy (but not WOT) accelleration. This was due to my stock injectors not being able to feed enough fuel into the cylinders above 4500 RPM.
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Old 09-06-2006, 12:22 AM   #11
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Quote:
Originally Posted by Shadow View Post
Thanks for the info I will change the plugs and wires, does anyone have a picture of the fuel lines to the FMU so I can see if they are indeed backward? Would getting the o2 clamp help even if I did not get a bipes right now?


The line going to the front of the rail should not have been touched.

The line going from the OEM FPR to the return hard line should be removed at the hard line. That line should connect to the offset fitting on the FMU and the OEM FPR. The center fitting should connect back into the hard line your removed the first line from. very simple.

The o2 clamp is only to prevent lean tip in during boost transitions. A great little device. But it wont help you retard timing. You'll need to stick with the static 6* for the time being.
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Old 09-06-2006, 06:44 AM   #12
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[QUOTE=kung fu jesus;43015]snowsurfer is right.[QUOTE]

HAHA Thanks knug fu!

What type of plugs and wires do you have?

Is there a "best" set of wires for a mild turbo set-up?

An o2 clamp will work for you but might not solve the problem completly. When I installed mine it was a big difference and well worth it.
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Old 09-06-2006, 08:11 AM   #13
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The NGK Blue wires (OEM replacement) are popular.
For Plugs NKG BKR7E's (-11).
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Old 09-06-2006, 11:47 PM   #14
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Its prolly due to the exhaust restriction, the plasic cross over pipe. When you upgrade to an IC and larger zorst this feeling will go away - add the Bipes and you'll be done.
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