mx5cartalk.com

Hey all,

So, I've just picked up a nice little NA6, but likely for different reasons to most. For a while I've been developing a very low cost, DIY friendly engine management system and finally reached the point where I needed a dedicated test vehicle. From what I've read around, the MX5 seems like the perfect testing platform for something like this, both because its injection system is fairly straightforward and standard, but also because of the large enthusiast community that might be interested in a low cost, simple, ECU.

There's a few minor mechanical things I need to do on the car first to get it running smoothly in stock form, but the next steps after that are to pickup an extra ECU, remove the existing board from, mount mine in it and hook up to the original plug.

If anyone is interested in checking out the project, the page is: http://speeduino.com/

I'll keep updating with how I go, but I expect about 2 months before I'll actually be in a point to try a test drive with it installed.

That's a neat project!

I'm using an AVR to gather data from my aftermarket ECU, not as the ECU itself!

My logging project is here:
https://github.com/timkent/adhd/blob/master/adhd.ino

I'll keep an eye on your site.

Cheers

Was looking at Arduinos yesterday thinking, 'surely this would be the ultimate DIY ECU platform...'
Nice work!

smy0003 wrote:Was looking at Arduinos yesterday thinking, 'surely this would be the ultimate DIY ECU platform...'
Nice work!

I don't know about ultimate, there's a LOT of hardware weaknesses that need to be worked around. It is very accessible though

I certainly believe that, I meant ultimate in the sense of what an extensive diy project it would be. Very impressive indeed.

Thanks, noisymime, for taking this project on - I'll be following with interest. Is your initial goal with the NA6 to emulate the behavior of the stock ECU?

LiteIsRite wrote:Is your initial goal with the NA6 to emulate the behavior of the stock ECU?

Pretty much. I want to make something that can function as a direct plugin replacement using all the stock sensors etc. That said, at that point you're better of doing the AFM delete and running a vacuum line to the ECU in order to run speed-density, would give a much better result, but making it work in a plug and play manner is the first priority.

To be honest, it sounds like a great idea.

There currently isn't much available if people are in that middle ground between turbos and big engine work (where you'd go for a standalone with all the tuning options) and those with just a pod filter an not much else (where you'd just stay stock ECU)

This sounds like a perfect option for people with mild mods (say intake, exhaust, cams) that they need to just do minor adjustments without having to spend full standalone money.

noisymime wrote:I want to make something that can function as a direct plugin replacement using all the stock sensors etc. That said, at that point you're better of doing the AFM delete and running a vacuum line to the ECU in order to run speed-density, would give a much better result, but making it work in a plug and play manner is the first priority.

Precisely what I was hoping you'd say! I don't personally have the knowhow to do an AFM delete, but I'm sure there are others here who do and I, for one, would like to replace it and it's restrictive inlet with something that breathes better - without a) cutting a hole in the firewall and/or b) spending a bunch of money for ECU features I won't be using.

hks_kansei wrote:There currently isn't much available if people are in that middle ground between turbos and big engine work (where you'd go for a standalone with all the tuning options) and those with just a pod filter an not much else (where you'd just stay stock ECU)

This sounds like a perfect option for people with mild mods (say intake, exhaust, cams) that they need to just do minor adjustments without having to spend full standalone money.

Couldn't put it better myself...

OK, so things are progressing really nicely with the ECU with a few cars now up and running on it etc.

Where I'm stuck though is with the car in its stock form... It's having a real hesitation under hard acceleration, bogging down and even popping out the inlet on occasion. I've done all the usual ignition related things, new plugs, wires, coil etc. Same problem.
The strange thing is that, converse to what seems to be the more common scenario, this only occurs when it warms up. When it's cold, everything seems to work fine and quick flicks on the throttle don't produce any hesitation. It's only when it warms up that things go bad. This makes me think it's more likely a fuel issue as I'm guessing that's what is getting changed mostly as it begins to warm up.

Anyone seen these types of symptoms before?

noisymime wrote: ... I've done all the usual ignition related things, new plugs, wires, coil etc...

Anyone seen these types of symptoms before?

Short answer is "no". What's your base timing setting?

LiteIsRite wrote:

noisymime wrote: ... I've done all the usual ignition related things, new plugs, wires, coil etc...

Anyone seen these types of symptoms before?

Short answer is "no". What's your base timing setting?

Currently everything is (To the best of my knowledge) completely stock, so I'm guessing the timing should not have been changed at all.

I assume you've setup the ecu to advance the timing as revs/load increase?

Also, I assume you've set the mixtures to go a bit richer at high revs/load?



Normally (on a carby car) i'd think it's either of them, or both, since too little ignition advance at revs can cause it to run like crap at the top, and too lean of a mix can cause similar.

I'd still suggest replacing plugs and leads first (that's pretty much standard before you do any tune) and as you said, fresh fuel (I'd also dump a bottle of injector cleaner in the current batch and use it up while cleaning the injectors)

hks_kansei wrote:I assume you've setup the ecu to advance the timing as revs/load increase?

Also, I assume you've set the mixtures to go a bit richer at high revs/load?[/quote

No, no. Like I said, its all still totally stock with the original ECU. I'm just trying to get everything running right in standard form so I can rule out problem areas when the custom ECU goes on.

I'd still suggest replacing plugs and leads first (that's pretty much standard before you do any tune) and as you said, fresh fuel (I'd also dump a bottle of injector cleaner in the current batch and use it up while cleaning the injectors)

All done unfortunately. They improved starting etc, but made no difference to this hesitation problem.

hmm,

Do you have any way of logging what the sensors are picking up? see if any of them are getting any odd readings?

I presume you've got a wideband o2 fitted and can see if it's abnormally rich/lean at the top?


The popping out the intake is odd, that's usually timing related, or a big vac leak.