MS PNP 2 Miata backfires but wont start...
 

Hey guys heres the deal 1992 miata 1.6l.

megasquirt PNP 2
GReddy tdo5h turbo kit
440cc injectors....
stock FPR
Stock TIMING (100% accurate)
STOCK IGNITION
AIT sensor (MAF DELETE)

She starts up and idles on the stock ecu but its obiously bad because the injector size etc.....

We uploaded the new firmware 2x on the new ecu.... We use the settings as per diy auto tune suggests for the 1992 miata.
IT wont start up and run on the MS like it should...

CAN SOMEONE HELP WITH ANY INFORMATION IVE BEEN at this for days and am ready to burn this god damn miata to the ground... THANKS

So, as you're able to connect to the MS with your laptop how about a cranking log along with the tune? More info about the setup; car = '92. engine = ?, FI (assuming you are otherwise why put 440cc injectors in).

Sorry I'll post a 10 second cranking log tomorrow. I would now but the car back fires so loud after cranking my neighbors thought it was a shotgun....

Engine 1992 1.6 litre
Weisco pistons
Eagle rods
Oem bearings
Oem crank
Arp studs
Felpro hg
Just had the head cleaned, valve job, etc
New timing belt and water pump
Etc....

UPDATE** i just found that the previous owner had the AIT air intake temp WIRES to the wrong pins in the maf connector...... SO that may explain some issues...

you're injecting too much fuel. Tell the MS to inject the right amount of fuel.

in other words: tune.

^^ What he said...

A good starting point, if the injectors really are 440cc would be setting req_fuel around 8.1ms

That should at least get to an idle assuming too much fuel.

When I go I to basic settings and fuel calculator I enter 1600cc in engine displacement. The go down to injector flow and enter 440 then click cc/min and burn it and it comes up with a calculated fuel number on its own? Is this wrong

no it's not.

Braineak I'm going to do a 10 second cranking log real quick. Then I'll upload it stand by

you certain the MAP sensor is plugged it? what basemap? what other tuning for fueling/cranking have you done?

heres the datalog....
 

Keep in mind guys after this cranking session.... along with every other one.. SHE BACKFIRES SO LOUD AND IM TALKING IT SOUNDS LIKE A BOMB..... MY 400whp 240sx has antilag and these backfires are louder...

that means it's dumping in a crap ton of fuel and then igniting all at once.

so that happened in about 4 seconds of cranking? are you sure they are good 440cc injectors? could they be bad or flowing much more than 440cc? the PW at cranking isn't THAT high.

why not try to lower the req_fuel more and more until it starts. that will give you an idea if it;s the fueling or if something else is at play.


this is a mspnp2? do you have a vTPS? do they make any notes about not using the factory TPS?

I think the basemap we are using is the 240cc one from diy auto tune..... heres the link...

DIYPNP MegaSquirt installation for the Mazda Miata

Post msq (tune file).
We'll instantly see what's messed up. I'm saying Req_fuel may be right but after start, warm up, and VE table haven't been changed.

I actually just went out and took a look at my MAF CONNECTOR.... There is 7 pins on it.... DIY's SITE SHOWS ONE WITH 5??? and the wire colors dont match per diy auto tunes website..... so i unplugged the sensor at the intercooler until i can figure out what the hell this wiring is now....

mine...
https://www.miataturbo.net/attachmen...ine=1384797843

THERES....
https://www.miataturbo.net/attachmen...ine=1384797843

https://www.miataturbo.net/attachmen...ine=1384797843

current tune.....
 

here it is.....

THIS IS A DIY PNP 2 AND IT HAS E30 VTPS......

also the injectors being bad really isnt a option keep in mind guys that this car runs and idles fine on the stock ecu.... just doesnt have a maf and struggles a bit because the 440cc on stock ecu with no maf lol

Sorry, forgot it's a 1.6.....

So I messed with a few more things.... I just can't get it to start on this megasquirt, I can like get it to fire for a second and it dies out..... So something in my tune is wayyyyyy off. I someone could look at that and let me know that would be awesome.... Also my injector should be unlimited fire? Or semi sequential?

the picture you posted was a 94-97 MAF connector, not a 90-93 AFM connector...

that was reading fine, and wasn't the issue. it's all in fuel tuning right now.



do what i said, half the req_fuel value in there right now and just see what happens.



and again: is this a DIYPNP or a MSPNP2?

All this megasquirt frustration and not being able to find any answers has me fed up to the point where I'm either A. Gonna part this car out..... Or B trade my megasquirt for someone's vortech fmu setup and
Call it a day.

I did that still doesn't start. Is there anyway you can look at the link for my tune file that I posted and go over it?

i did, and i didnt see anything that stood out.


i also asked things about your vtps and specific megasquirt...

My specific megasquirt is DIY pnp v2 and my tps is a e30 tps of some sort..... I calibrated it and all.

I just don't understand what could be going wrong here if the stock ecu has the ability to fire right up and idle but the megasquirt can't do that with all the settings set correctly from DIY auto tune.... Something here is wrong..... I'll go over my timing again! Then I'll pull and test each wire for spark using test mode... And I'll do the same with injectors..... And if all is good then in out of ideas here guys...

It's probably your timing, adjust it in MS or by hand. Trial and error. Megasquirts should come with replacement starter motors lol

it could be anything. it's happened to all of us.

who built the MS?

Did you post a short vid of your car on facebook on 11/15 trying to idle with the stock ECU?

YEPP THATS ME

Tadd bailey... Member on here REDTURBOMIATA

AGREED on Starter motors LOL. But I have a timing light on her and shes perfect STOCK timing!

Your car barely could idle and REALLY rich. Not what I'd call 'idles on the stock ecu".

Like Brain says, you gotta get your fuel inline before it'll start. Maybe you should reload the base tune and ONLY screw with the req_fuel.

well what did you think it was gonna act like on a stock ecu with 440cc injectors, and a full turbo kit, with no maf, and a ait sensor.....

Well... good luck to you then!

not trying to be a dick im just extremely frustrated

timing was a tooth off when i just checked..... FUCK hopefully after i fix this she will stay running.

I meant ignition timing. Change your trigger angle in MS or adjust the CAS. No wait, read the manual.

We put the engine in time last time and didnt turn it over a few times to make sure the slack didnt change the engine timing.... We just assumed it was right.... it was off a tooth when we just checked. With that said is this where It has to be at this bottom pulley? WITH EVERYTHING LINED UP IN THE TRIANGLE UPSTAIRS and downstairs....

https://www.miataturbo.net/attachmen...ine=1384834427

I knew what you meant but we thought we should check overall timing belt timing... thats where a big problem was...

The problem is that you keep posting stupid shit without explaining what it is you're actually doing to try and fix the car. My car keeps backfiring. Great, you said that in the first post.

How about you actually try and figure out if your timing offset is correct in Tunerstudio and get back to us, your belt being off one notch isn't making your car backfire.

It would be nice to know how exactly to figure my timing offset out. Did you miss the part where I said I'm new to megasquirt and this is a learning expirence for me?!?! I'm just trying to figure things out as I go and get things done one thing at a time.

Have you got 1/4 and 2/3 around the right way on the MS?

Hold the throttle wide open with flood clear enabled and get someone to check the timing with a timing light on the front most cylinder.

actully, just trying to start it with more throttle would lean it out as well and help point you to a solution too.

pretty sure I built what-his-face's diypnp, fwiw.

Okay this may be a long shot... But I've done it before and almost ripped my hair out because of it.... Is your vac line hooked up to the megasquirt?? Easy to overlook, and will cause very rich conditions!!!

Coupled with bad timing, would almost certainly cause no-start