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Old 03-05-2007, 12:33 PM   #1
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Default OBD2 questions, intro thread

Hi everybody. Im a complete noob to miatas but not to forced induction. I've owned:

92 prelude S t3/t4 (FMU, blah)
93 240sx t3/t4, emanage ~300whp
88 civic hatchback t25 (turboedit) ~170whp
90 civic hatchback 14b (turboedit) ~200whp

I've always wanted a miata and now I've finally got one. It's a 96 with Torsen LSD and <100k miles.

Boosting is still a good 6 months down the road for me but until then I'm going to be researching, trying to help out boost noobs and probably asking some questions of my own.


I will probably start out with a mild emanage/pump/injectors setup with goals in the 200-225whp range, running a super-60 or comparable.

Here are a few questions I havent seen answers to:
1. Do OBD2 Miatas still "need" an o2 clamp?

2. When does the stock MAF max out (horsepower wise?)

3. I think I saw a MAP sensor under the hood also, is it going to be angry with me when it sees boost? Will the Emanage take care of that for me?

4. Fooling the post-cat O2. I live in SC (nun of demz emissitory regumalations) and hate the environment so I'll be running cat-less, or at least a high-flow cat. Can I keep from getting a CEL somehow?

5. Looks like there's some coolant lines in my way, should I just be able to heat-wrap everything and avoid re-routing?
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Old 03-06-2007, 08:36 PM   #2
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the super 60 is not my choice aiming @ 200-225...
Id go with a t25-28

some answers;

1 The o2 clamp on the front sensor seems to be the best option....not sure.

2 not @ that hp level...

3 no map sensor on a 96 oem...

4 remove cel light? Serious the 2nd sensor is checking the cats working.
Don't have obd 2...sorry can't help

5 heater lines , wrap them, but watch your temp... some overheat some don't ....
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Old 03-06-2007, 11:18 PM   #3
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Quote:
Originally Posted by SloS13 View Post
Hi everybody. Im a complete noob to miatas but not to forced induction. I've owned:

I will probably start out with a mild emanage/pump/injectors setup with goals in the 200-225whp range, running a super-60 or comparable.

Here are a few questions I havent seen answers to:
1. Do OBD2 Miatas still "need" an o2 clamp?

2. When does the stock MAF max out (horsepower wise?)

3. I think I saw a MAP sensor under the hood also, is it going to be angry with me when it sees boost? Will the Emanage take care of that for me?

4. Fooling the post-cat O2. I live in SC (nun of demz emissitory regumalations) and hate the environment so I'll be running cat-less, or at least a high-flow cat. Can I keep from getting a CEL somehow?

5. Looks like there's some coolant lines in my way, should I just be able to heat-wrap everything and avoid re-routing?
1. OBD-II Miata's don't need an O2 clamp above 4000 RPM, they run open loop above 4k RPM. Personally I think that the super 60 is a better choice than the T-25/28 for 200+ RWHP, just my opinion.

2. The stock MAF sensor craps out at around 400 CFM (roughly 240 RWHP.)

3. There is no MAP sensor on the Miata for engine management purposes.

4. The post cat O2 code won't effect anything but you will get the cell without a cat, a high flow cat will work fine.

5. Either re-routing or wrapping will work. Many people opt to reroute for various reasons.

Mark
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Old 03-06-2007, 11:23 PM   #4
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Your car sounds like an excellent candidate for boost. And there's plenty of experienced hands around here to help you out, poke fun at you from time to time.

The second O2 sensor is basically there to monitor catalytic efficiency. It's expecting to see a "lean" condition most of the time, indicating that the converter is doing its job.

That being said, a "high-flow" converter will probably be sufficient for your needs. I recently passed CA emissions using a 2.5" Magnaflow on my turbo'd 1.6. And while removing the converter might theoretically gain you an extra 2 HP at the redline, modern honeycomb converters really don't deserve the bad rap they've inherited from their predecessors. If you're set on removing it, you may be able to fool the ECU by leaving the sensor in place but diking out the sense line and feeding it a fixed reference voltage instead. Easy enough to do with a couple of resistors. Actually, I really ought to design and sell that...

You'll still want an O2 clamp for the primary sensor if you decide to keep the stock ECU. Just my opinion, but it's good practice for *any* car where you're trying to exert control over the stock fuel system.

Everything GreddyMX5 said is pretty much bang-on. No Miata from '90 to '05 has ever had a MAP sensor, except possibly the factory turbocharged Mazdaspeed models. Never worked on one of those.

Those coolant lines are your heater hoses. While you're replacing them, it's not hard to slip some Summit Racing brand sleeve around them. You are replacing them, right?

You'll also want to wrap pretty much the whole brake system in a heat blanket. Somewhere around here there's a picture of somebody's molten master cylinder cup. Very bad...

Welcome to the club.
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Old 03-07-2007, 09:36 AM   #5
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Awesome thanks for the replies!

The reason I'd go with the super-60 over a T-2-small would be sacraficing a bit of spool up to having room to grow without having to re-do everything later on.

I'm used to working with Hondas and Nissans and we've never used or needed any of this o2 clamp business. I looked at the o2 clamp for dummies and it looks easy enough. I may even make a small batch of them to make a few bucks and help the soderdly challenged.

The reason I would want to go catless is, of course $ and simplicity of the exhaust system but I'll put some more thought into that. Might just be best to run a high-flow.

What I mistook for a map sensor must have been something else. I'll take a pic of it soon.

As far as replacing those coolant lines, honestly I don't know. They look and feel like new...well actually everything under the hood is just about factory perfect but wrapping them would definitly be a wise decision.

Gotchya on the heat blanket. I had the same concerns with my turbo s13.

When the time comes, I'm also gonna have to figure out what I want to do with the EGR - either block it off and have a constant CEL or rig up some stuff to keep it in-tact.

Ideally, I want to go megasquirt at some point in the future. Nothing beats a complete standalone system like that. I've got a few buddies that have done some amazing things with them.


Speaking of - here's my old S13. I miss her :(
http://video.google.com/url?docid=27...EaDfU2mPekWrbw
http://video.google.com/url?docid=79...yXttlUTByqkLyw
http://video.google.com/url?docid=-3...xhxu8GvYrlVKfQ
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Old 03-07-2007, 09:44 AM   #6
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Quote:
Originally Posted by SloS13 View Post
Awesome thanks for the replies!

I looked at the o2 clamp for dummies and it looks easy enough. I may even make a small batch of them to make a few bucks and help the soderdly challenged.

Uh Oh Competition

I make and sell an O2 clamp with instructions, switch, and priority shipping for $65 if you are interested.

And welcome to the forum anyway:gay:
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