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?

Thank You!

no.

it is likely already lean from the flattop

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.

Why would you swap a BP05 cam into a BP4W?

i usually just mail my ECU to someone and hope they mail it back in a manner that wont blow my motor.

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.

What makes you think the stock ECU is fully calibrated beyond the factory airflow parameters?

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

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 :party:

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.

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.

Are you saying that those of us on the Alaska coast shouldn't put bolt ons on our car?

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.

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?

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.

What's the typical useful life of a knock sensor?

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
https://www.miataturbo.net/attachmen...ine=1442355048

check out those lovely IDC's :giggle:

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.

You should probably clarify exactly what you mean by "good," in this case, because i'm pretty sure my definition of the word is wildly different than yours.

The GReddy kit was more like 4psi, and it used a rising rate fuel pressure regulator to handle extra fuel in boost, and you turned the timing down to 6 degrees base which killed low-end power. At 6psi, the car knocked anyway, so you had to run a Bipes to keep that under control, and transition into boost was lean unless you ran an O2 clamp.

So what you're saying is that Mazda designed the car to handle 5-6psi "good," right?

None of the stock non mazdspeed ecus can handle boost without band aid mods.

In reference to OP .. My well built N/A Engine would run on the stock ecu, at a cost of 10hp/15 lb tq. A proper ECU will make more additional power than any other single mod, safely with better drivability. No brainer really.

Whoa guys, I wasn't trying to talk him out of getting a programmable ECU. I thought he was asking whether or not his car would blow up with cams on the stock ecu.

Good in this situation = "not cause the car to explode."

OP has obviously spent a megasquirt worth of money on mods already. I don't see why he doesn't do things the right way, but it's none of my business.

Install a wideband if you are nervous. Install an ECU if you want a good $/hp addition to the car.

Thanks to everyone for the responses.

Due to my "Posts=1" status (now 2!) I derived a bit more benefit from the more direct responses (but an educational initiation nonetheless).

The car is a dedicated track day car. I was hoping to get a couple of more events in (with the cam installed) before the season is over. Once the season is over (during winter months), the plan is to get a 2.0 block from mccullyracingmotors.com with the 11:1 pistons, clean up the head and add the Megasquirt.

Meanwhile, I'm getting the AFR gauge installed just in case, and if there is a lean condition, I'll move up the Megasquirt install. I'm just trying to avoid having to take the car to the dyno/tuner twice @ 450.00 a pop…

Thanks again.

MD

IMO, if you're actually driving this hard on the track instead of puttering around the street while you save up for a megasquirt, you need to install the megasquirt and wideband yesterday. Hard driving for long periods of time is going to be a lot less forgiving of a bad/nonexistant tune than hard street driving.

I don't think you're going to be getting much power gains from your setup without adding the ECU and the only way to properly get rid of worries about adequate fuel is to run a wideband. If you can afford a stroker motor next year, you can afford to install a megasquirt and wideband this year. Programmable ECU and wideband isn't an optional part in any serious build.

Makes a lot of sense on all counts. Thx

My ears hurt just reading that....lol

Hey, there is a resonator where the cat was :laugh:

Seriously though, It's a track day car, and I never drive it without earplugs...