collin4170

I have an ongoing problem. I was driving going about 60 hit a pot hole and engine died all lights stay on. I try and start it it will crank but not start. I cannot hear the fuel pump kick in and the cluster beeps and does an rpm sweep. I plug in the stock ecu and it runs. I sent my wiring and ecu to flying miata it all checked out good. I charged my battery when it got back and it started up. Drove it for 2 weeks and happened again going 70 down the highway and hit pothole. Not on purpose.. And car died. Runs on stock ecu. I'm completely lost on what it could be. Clearly everything works fine on stock ecu. This all started after I replaced the battery. But I have tested the new battery.
Anyone experienced this problem?

codrus

Can the laptop talk to the Hydra over the serial port?

--Ian

collin4170

Ya it does. No codes pop up

codrus

So it's basic engine troubleshooting then. The Hydra needs to see the cam and crank angle sensor inputs and be able to decode then, then it can drive the fuel and spark appropriately. One of those things isn't happening, and you need to figure out what.

Are you getting fuel (are the plugs wet?). Are you getting spark? If neither of those, then probably the Hydra isn't syncing. If you turn on data logging, what does the log show? Does it indicate an RPM while cranking?

Does the MAP sensor work properly? If you disconnect it from the manifold and hook it up to a mity-vac instead, can you get the MAP display to change by pulling a vacuum on the port?

--Ian

collin4170

Well if that was the case why would it run on the stock ecu? Just seems goofy. But I will be checking everything over tomorrow

codrus

The stock ECU uses a MAF (air flow) sensor, not a MAP (air pressure) sensor.

--Ian

collin4170

Got a chance to check map sensor with mityvac it is working properly. This all started when I changed the battery. But the battery tests good. And starts fine with stock ecu so I think it's coincidence. I'm out of ideas here. The maf is deleted due to having the fm2.

codrus

You say you can't hear the fuel pump -- did you used to be able to hear it? Have you checked for fuel pressure? When you say you "plug in the stock ECU and it runs" do you mean the fuel pump runs, or the car runs?

--Ian