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Old 09-14-2015, 11:05 PM   #1
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Default Can my stock ECU handle one more mod?

Re:N/A 99 miata 1.8

If I have K&N CAI, Ported Flat top manifold, RB header, 3 inch exhaust , minus Cat, plus magnaflow muffler…..

Will my ECU be able to handle the addition of the BP05 cam?

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Old 09-14-2015, 11:42 PM   #2
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no.
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Old 09-14-2015, 11:52 PM   #3
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it is likely already lean from the flattop
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Old 09-15-2015, 12:33 PM   #4
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I can't even imagine modding my car without a wideband and egt.

Question though, shouldn't the stock injectors be able to keep up with flattop and cams? None of his mods should affect the accuracy of the stock airflow meter. I thought the stock injectors had enough headroom to run a few pounds of boost.
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Old 09-15-2015, 12:36 PM   #5
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Why would you swap a BP05 cam into a BP4W?
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Old 09-15-2015, 12:48 PM   #6
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Quote:
Originally Posted by AlwaysBroken View Post
I can't even imagine modding my car without a wideband and egt.

Question though, shouldn't the stock injectors be able to keep up with flattop and cams? None of his mods should affect the accuracy of the stock airflow meter. I thought the stock injectors had enough headroom to run a few pounds of boost.
i usually just mail my ECU to someone and hope they mail it back in a manner that wont blow my motor.
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Old 09-15-2015, 12:51 PM   #7
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FWIW I have a similar set of mods (intake, BP4W, squaretop, BP5A cam, NB2 header, catback) and my NB doesnt run lean at all.
I measured A/F by pointing a GoPro at my cluster and WBO2 gauge (pre-cat) and it went from about 13.2 to 11.6.
I'm definitely not getting my money's worth out of these mods without an ECU, but it's not running dangerously lean.
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Old 09-15-2015, 05:32 PM   #8
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Quote:
Originally Posted by AlwaysBroken View Post
I can't even imagine modding my car without a wideband and egt.

Question though, shouldn't the stock injectors be able to keep up with flattop and cams? None of his mods should affect the accuracy of the stock airflow meter. I thought the stock injectors had enough headroom to run a few pounds of boost.
What makes you think the stock ECU is fully calibrated beyond the factory airflow parameters?
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Old 09-15-2015, 05:34 PM   #9
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Quote:
Originally Posted by scenturion View Post
FWIW I have a similar set of mods (intake, BP4W, squaretop, BP5A cam, NB2 header, catback) and my NB doesnt run lean at all.
I measured A/F by pointing a GoPro at my cluster and WBO2 gauge (pre-cat) and it went from about 13.2 to 11.6.
I'm definitely not getting my money's worth out of these mods without an ECU, but it's not running dangerously lean.
oh right, I remember your thread.
that was pretty cool.
if all NB1's run like yours then I guess he doesn't really have a problem.
or shouldn't
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Old 09-15-2015, 05:36 PM   #10
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Quote:
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What makes you think the stock ECU is fully calibrated beyond the factory airflow parameters?
Good engineering practice.
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Old 09-15-2015, 05:48 PM   #11
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Good engineering practice.
I'll rephrase: What makes you think the accountants at Mazda were willing to pay the calibration engineers to calibrate the stock ECU beyond the factory airflow parameters
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Old 09-15-2015, 05:53 PM   #12
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Quote:
Originally Posted by Savington View Post
I'll rephrase: What makes you think the accountants at Mazda were willing to pay the calibration engineers to calibrate the stock ECU beyond the factory airflow parameters
A desire not to have their engines blowing up left and right, combined with the knowledge (however unpleasant) that a certain percentage of owners are going to throw bolt-on mods at the car, and the calculated reality that a few hours spent on an in-house dyno are far cheaper than warranty claims, frivolous lawsuits citing the Magnuson-Moss act, and bad press.
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Old 09-15-2015, 06:00 PM   #13
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Quote:
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What makes you think the stock ECU is fully calibrated beyond the factory airflow parameters?
Because engineering common sense? You don't design for the atmospheric conditions inside the factory, you design for the most extreme conditions the car is likely to encounter in Alaska, Texas, Florida, the Rockies, etc.

They don't want someone to drive the car in cold weather at low altitude and blow it up because the air was 20 percent more dense than in the hiroshima testing facility where they designed the engine.

edit: also, like Joe said above, it's less of a hassle to build in a bit of insurance than to have a ton of preventable breakages on your hands during warranty period. The car shouldn't melt pistons because the sensor gets a value that is a bit out of the expected range.

Also, how do you know that every factory flow sensor is perfectly accurate? My guess is that Mazda assumes they aren't which is why they don't just have an open loop that consists of reading temperature/flow/etc and dumping a set amount of fuel- they constantly recalibrate the amount of fuel to try and maintain a proper mixture. They probably also assume that fuel pressure is slightly variable, injectors get dirty over time, etc.

Last edited by AlwaysBroken; 09-15-2015 at 06:12 PM.
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Old 09-15-2015, 06:01 PM   #14
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Are you saying that those of us on the Alaska coast shouldn't put bolt ons on our car?
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Old 09-15-2015, 06:14 PM   #15
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Everyone thinks OEM's actually take everything into account, and then you run into into cars like the MSM, and your head explodes.
There are many others like that btw.

I chuckle extra loud when I hear stupidity like: " Millions of dollars and years of development went into XX oem ecu, they know what they're doing".
Most of those people don't know what a recall is.
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Old 09-15-2015, 06:23 PM   #16
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I agree that the MSM was a slapped together pile from the factory, but what we do know about the stock miata ecu and sensors suggests that the stock air flow sensor is good up to about 5-6 psi of boost. It was good for it in the 1.6, the 1.8, etc. The old greddy kit was a little turbo pushing 6 psi of boost directly into a crossover tube that went into the throttle body. For a long time, people were running about 8 psi on a fuel pressure regulator and a timing box. Stock ecu and airflow sensor there too, no?

edit: I might be mis-remembering stuff from 15 years ago, but I thought the greddy was just sucking air through the stock airflow meter, no?
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Old 09-15-2015, 06:30 PM   #17
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Quote:
Originally Posted by Joe Perez View Post
A desire not to have their engines blowing up left and right, combined with the knowledge (however unpleasant) that a certain percentage of owners are going to throw bolt-on mods at the car, and the calculated reality that a few hours spent on an in-house dyno are far cheaper than warranty claims, frivolous lawsuits citing the Magnuson-Moss act, and bad press.
I got a PM this morning on M.net from a member who just added a squaretop to his '01 with a stock ECU, and is now complaining that it's detonating above 5000rpm, and he wanted to know what he should do.

I think you guys give entirely too much credit to the accountants/engineers at Mazda circa ~17yrs ago.
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Old 09-15-2015, 06:52 PM   #18
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What's the typical useful life of a knock sensor?
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Old 09-15-2015, 07:08 PM   #19
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Quote:
Originally Posted by AlwaysBroken View Post
I agree that the MSM was a slapped together pile from the factory, but what we do know about the stock miata ecu and sensors suggests that the stock air flow sensor is good up to about 5-6 psi of boost. It was good for it in the 1.6, the 1.8, etc. The old greddy kit was a little turbo pushing 6 psi of boost directly into a crossover tube that went into the throttle body. For a long time, people were running about 8 psi on a fuel pressure regulator and a timing box. Stock ecu and airflow sensor there too, no?

edit: I might be mis-remembering stuff from 15 years ago, but I thought the greddy was just sucking air through the stock airflow meter, no?
and before that people were running carbs.
and before that people used steam.
before, horses.
get my drift?


PS: get this, before doctors used to never wash their hands before cutting people open and stuffing their hands inside of them.. and some of those people lived several years after. well, like 20% of them.

here's a log from my msm on stock injectors running only 9.5psi tapering to 8.5


check out those lovely IDC's
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Can my stock ECU handle one more mod?-injectors%2520over%25209000.png  
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Old 09-16-2015, 12:14 AM   #20
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Jesus, it goes to 11. And beyond.

Still, I think that's pretty encouraging considering the OP is only running a flattop and a cam. That's nothing like running 9 psi.
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