03 VVT Miata- SLOW- 140k- Trying to figure out why it is slow? Power feels linear. - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-07-2013, 02:59 PM   #21
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Originally Posted by Doppelgänger View Post
It's all good
If the VVT is out of whack, it should throw a code. I have not seen it fail for the most part, other than when people pull it apart by accident. I'd also throw a timing light on it just to make sure the timing is correct. It would almost seem more likely that the timing would be off or something of that nature than the converter being clogged. It would help you greatly if you could throw a WB02 on there and watch your AFRs.

If you're going to do any playing with the exhaust, you might as well just get a newer, better system. I'd highly recommend looking at Enthuza exhausts.

Funny what a little vacuum leak can do.

I've been told about a VVT tuber per se'. It's where the actuator valve that called for replacement via the service bullitin. I'm going to blow it out with carb cleaner.

The only reason that I am leaning towards the CAT being clogged is that
others that have had ignition problems have had to replace their CAT converters shortly afterwards. Trust me, I'm not excited about throwing money at a problem and seeing if it will fix it.


Next up, Changeing out the coil pack. By this point I would think that teh car will have a littel bit more umph...
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Old 05-09-2013, 08:31 AM   #22
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IMHO/IIRC, The majority of the problems of the ignition/converter you speak of were with the NB1 (99/00) cars and their coilpacks going bad (pretty common), which would cause raw fuel to get into the cat and superheat the element and eventually blow it out. I have not really heard of any problems with the NB2 ignition and this issue.
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Old 05-09-2013, 08:00 PM   #23
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Yeah the 01+ coilpacks are much better. Cats fail when the car runs too rich for too long, which is why a failing coilpack kills the cat.
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Old 05-10-2013, 02:50 PM   #24
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Yeah the 01+ coilpacks are much better. Cats fail when the car runs too rich for too long, which is why a failing coilpack kills the cat.
I'm changing the cat next week. If this car doesn't get any more power or torque than I will be saying goodbye to miatas forever.
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Old 05-10-2013, 03:08 PM   #25
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I'm changing the cat next week. If this car doesn't get any more power or torque than I will be saying goodbye to miatas forever.
Wow, you're easily discouraged. Maybe making a slow car fast isn't for you.
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Old 05-10-2013, 04:05 PM   #26
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Wow, you're easily discouraged. Maybe making a slow car fast isn't for you.
He's not even boosted or considering boost. He just has a stock Miata.
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Old 05-10-2013, 04:26 PM   #27
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He's not even boosted or considering boost. He just has a stock Miata.
That was my point, if he gets discouraged this much diagnosing his stock miata then he should not even consider adding the complexity of a turbo setup and standalone EMS to the equation. Stock cars are easy to diagnose.
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Old 05-11-2013, 05:37 PM   #28
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Wow, you're easily discouraged. Maybe making a slow car fast isn't for you.
You may very well be right. Some guys LOVE to build. Some guys love to polish. Some love to brag about what beats what compared to the latest car and driver mag... I like to race. My car set up skills suck. You would think that after racing for the past 35 years I would have learned a thing or two about car set up and such.

Some people say that this car runs perfectly fine. I disagree. It has more power hidden inside and I need to unlock this power before I even think about going FI.

Once I figure this out then I'll start working towards either a Winter build or a good person to take it to for a turbo install.

The only way I'll go FI is if it's plug and play. I'm not teh guy for remapping fuel curves at teh start line. And I hate it when a car leaves me stranded.

I've owned two supercharged Corvettes. Both L98 C-4's and both were a nightmare. Tubes comming off all the time. Limp home mode. Incorrect air fuel- blown motors. Swore off of boost a long time ago. But I've heard that you guys have the turbo kits for a miata down to a science.

I hope that this new CAT will open the car up a bit. I currently own two miatas, a 91 stock with 198k and an 03 vvt, guess which one is currently faster?

I need to change this.
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Old 05-11-2013, 08:49 PM   #29
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But I've heard that you guys have the turbo kits for a miata down to a science.
Well, yes. But it is a science. Are you actually interested in learning? Your post makes is sound like you may not be.

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I currently own two miatas, a 91 stock with 198k and an 03 vvt, guess which one is currently faster?
And guess which one is lighter. With the exception of the Mazdaspeed, Miatas did not get appreciably faster through the years. They got heavier and a bit more power was added to compensate. I would not change the cat unless a backpressure check or visual inspection showed that it was bad. Could easily be a waste of money.
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Old 05-11-2013, 09:01 PM   #30
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Maybe try finding someone local who knows Miatas very well and have them take it for a spin?
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Old 05-11-2013, 09:06 PM   #31
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Originally Posted by Red5 View Post
On some vehicles, after sitting overnight and being started, the MIL comes on and DTC P2004 sets into PCM memory. This occurs because vacuum (momentarily) does not flow into the Variable Tumble Control System (VTCS) shutter valve actuator. The contact surface between the valve and the valve body inside the check valve is smooth, causing the valve to momentarily stick before more vacuum applies, opening the valve.


Is the VTCS something that could get in the way of this motor making power?
Definitely. Perhaps you could temporarily wire the VCTS arm open and test drive it to see if the car feels better. If it's staying shut the car will definitely not build any power.

(I ditched it completely on my car, removed the butterflies, pulled the shaft out and epoxied the shaft bores.)
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