HELP car will not run when warm. DIYPNP
 

Hey all!

I'm experiencing a pretty strange issue with my car. It will eventually start when cold and idle but when warms up the car will not stay running at all.

I've played around with the ASE and warmup to try and keep the car running but i've had no luck.

When the car is cold and idling it seems to be running great. AFR's show normal but as soon as it hits ~100 degrees it starts to taper off (lean out) and stalls out.

I'll attach one log of the car running cold and another of a start attempt when luke warm.

Today I noticed that EGO control was on and I tried deactivating this setting but I'm getting approximately the same results.

If you could check out my .msq and logs and shine some light on this problem I would greatly appreciate it. I've done a ton of reading and can't seem to solve the issue.

All gauges seem to be reading something believable.

My car:
1.8
Toyota COP
550cc injectors
m45 supercharged & intercooled
stock fuel pump
AFM delete

Again, any help is super apprecaited!

So the afrs taper off, as in leaning out? And then it dies?

Dump some fuel in your idle cells, or up your req fuel, and try again. It needs to run properly while warm, then you fun ase. Sounds like it's relying on ase to stay running, and dies when it shuts off.

Yes, I believe it's leaning out. It's very hard to tell since the engine wont stay running long enough to get an accurate reading from the afr gauge. The only measurement I have is with a cold engine, AFR's seem to be great then it seems to creep lean, eventually stalling out.

As an absolute last resort I tried ramping up the VE table cells in increments of ~10. Honestly it seemed to get worse once I went past 100 in the cells.

I've also tried combining zero warmup with high VE table numbers, same result..

I think my BARO settings might be wack.

Here are my new BARO settings, I kinda just guessed from what I thought made sense. Can anybody double check these for me?

The settings previous:

%: 147
Rate: -47


I placed +47 in there and it seemed to start up but possibly just because i let it cool down.

Dead Battery
 

I'm thinking after sitting all winter the battery is toast. It's on the charger but I'm not seeing past 11 volts, even when running...

That's an alternator problem. Any battery will show 14 volts, shitty ones just won't hold it.

its almost like there's a setting based on AIT temps that leans out the tune...

so weird.

Got a fresh battery in my car today and it absolutley has an effect on start/run quality. However I'm still seeing below 12v in tunerstudio. I'll have to install the alternator tomorrow.

I'm stumped by one thing still.. In the screenshot above I posted that I had to increase the barometric rate from (-47) to +47. This still seems to be the case.

Can someone explain this type of correction to me? I'm not understanding why this even changes anything. My barometric correction curve is set to 0 across the board.

what voltage are you actually reading on your injectors?

your issue is not barometric settings; put it back to default values for your map sensor (do you even have a constant baro sensor?)

barometric corrections are turned off, so it's REALLY not the issue...


I'll give you a hint: Someone else JUST posted the solution.

I'm just using the stock map sensor no external baro on my setup.

I'll look at the AIT settings but I thought it was turned off for now..

having AIT corrections turned off IS the problem, especially when the code pulls fuel when it's warm.

Oh, now I get it.

Wont run
 

Ok - After installing the alternator peak voltages increased but I'm still having issues..

Same symptoms as before. After a lot of cranking I could get it started cold and wouldn't stay running when warmed up.

I read the AIT thread about canceling out the hard coded ideal gas law but I can't access the non-linear table. I ended up modifying the MAT air density table to some settings found in another thread.

I'm also unsure what to do with my MAT/CLT table

I've attached a couple logs. Mostly start attempts, a couple with extra fuel and a couple with less fuel. I'm getting about the same result from both. My running log was to big, I'll have to try again tomorrow.

Any clues here? I'm quite stumped...

Wiring issues
 

Ok I think I found my issue this evening.

I thought maybe my idle air control valve was stuck open or closed causing issues. So I unplugged it and was going to remove it. However once unplugged the fuel pump continuously primes. Obviously not what I was expecting.

So after some further testing and digging here is what I've found.

With the green 2 prong connector on the idle control valve unplugged megasquirt gives a very strange RPM reading. It spikes to 178 and then 0 and repeats. The car will not start. and gets a VERY low voltage reading of ~5.5

With the idle control valve still unplugged, I then tried jumpering the fuel pump using the diagnostic connector and the fuel pump primes but at the expense of ALL ECU connection.

I then plugged in the stock ecu to figure out if it's a wiring issue or a megasquirt issue. Once the stock ECU is plugged in, the idle control valve reacts how you would expect. I can hear the valve click once when un-plugged in and click again when plugged back in. No strange fuel pump priming with the stock ECU plugged in.

I"m unable to try and start the car with the stock ecu because of my COP's and MAF delete but I suspect it would run with factory equipment in place.

So to me it seems I have an internal megasquirt issue. What should I be looking for???

A couple on a side notes:

-With the car off in accesory mode the battery reads 12.48 with a volt-meter and with the megasquirt connected it only reads ~10.10.

-I'm unable to get the fuel pump priming in output test mode but can hear it click on and off when the key is turned.

-The IAC pin goes to 4Q as per the DIYPNP instructions.

-The Fuel pump in and out also look correct.

-My board was NOT originally built for a 1997MY

This is such a strange issue, what do you guys think?

1997 Miata
 

Took some pictures of my board.

https://www.miataturbo.net/attachmen...ine=1375370457

https://www.miataturbo.net/attachmen...ine=1375370457

https://www.miataturbo.net/attachmen...ine=1375118511

https://www.miataturbo.net/attachmen...ine=1375118511

Examined the miata harness and couldn't find any faults with the factory ECU plugged in.

Ended up snipping the internal IAC wire. Now the pump primes irregardless of the actual IAC valve plug.

Anyone want to chime in here? I'm all thumbs with electronics

Took a close look at the ECU again and R39 looks pretty beat up.

https://www.miataturbo.net/attachmen...ine=1401150905

Is this fixable? Or do i need a new ECU?

You can replace the resistor, but you'll need a hot air rework station to do so, as that is a surface mount resistor. I have no idea if DIYAutoTune does any kind warranty etc, that would either help you in this situation or void it if you fix it yourself, just commenting on how I personally would replace a bad surface mount chip in other instances.