DIY PNP miata stopped starting
 

I have a 94 with a diy turbo and ecu, and i just finished it and it started right up first crank last week, idled it for a few minutes, set the timing, then rejoiced and went to bed.

What I didnt do was turn the car off or unplug the battery tender for almost a week until I was back in the garage and now the car will not start no matter what I try. The sparkplugs had fuel on them, it seems to be firing sort-of, but when I crank it and then do a flood-clear for a while there is quite a bit of cloudy unburt mixture that is exhaled.

Any advice on what I should look for would be greatly appreciated!

small update, it apears to be firing sort of, as it temperatures are rising and there are burbles coming from the motor: still no start though

Please post your MSQ and a data log of an attempted start.

I will post MSQ and log tonight, but I found a few troubling things this weekend, I'm hoping someone here can help me troubleshoot.

So I have discovered that lots and lots of gas was dumped into the motor while the car was on, the oil came out at double capacity and smelled strongly, so I think the injectors were either priming periodically or super leaky (not sure how that works).

The gas gauge is showing empty, I put some more gas in the tank, still showing empty.

The real kicker is that now, even when I put my foot on the floor, with flood clear set to 70% TPS, tunerstudio showing 100% TPS cranking for a few seconds, the plugs come out totally soaked.

If I hold the throttle down at 100 and crank for 20 seconds, I can hear combustion and sometimes even see flames at the end of the downpipe (no exhaust yet).

My working theories are either:

1. Something on the fuel delivery side (drivers on the board, something else?) is fried and holding the injectors open.
2. Something from the tank got through the filter and is clogging the injectors, preventing them from making a seal.

If it helps at all it’s a DIYPNP from DIYautotune with basically the startup map from their website. I have dramatically leaned out the cranking pulse width with no change in results, replaced plugs, and verified that both old and new plugs have good spark.

Can you swap the stock ECU back in and see if the car starts with that?

Will that work with 550cc injectors?

Probably not, but maybe. Where are the injectors from? They new or used? If used did you get them cleaned and flow tested before you installed them?

I got the injectors of another member of this forum, he had some test sheets from when he bought them, and honestly I just installed them. they were very clean, and it did start and run once, i'm just concerned that now theyre dirty/broken maybe? I can try the stock ecu tonight after I post the startup log Matt asked for above.

I should also mention that I did have the car working with the 550s in april with no turbo for a few weeks with no issues, also on megasquirt ecu

Not on our startup map. You will need to rescale Required Fuel or it will flood your engine.

right, I figured. I finally got around to fixing my internet so I could upload these files. attached are the log and the msq. I am going to get some new injectors on order and hope thets what my issue is. With the tune, I know its far leaned out on crank, thats because the plugs are so wet!

If anyone has some other ideas I would be very grateful.

looking at your msq my first guess is that your MAT air density table is adding too much fuel when the temps are cold, and it's flooding the motor.

zero that table out to 100% across and try again.

That's a special purpose log for RPM issues - can you post a regular data log?