1G Compression test now no start

[enriquez2000]

Did a compression test and numbers were low as expected(car still ran ok).. tried to start the car after checking all 4 cylinders and it acts like its not getting gas stumbling and thumping at 500rpm with foot at wot and dies as soon as i let off.. starter fluid seems tobget it to start a bit better but eventually it gets used and goes back to thumping.

Used link to verify fuel pressure to the rail. Checked injector pack resistance and it was good. Coils are good and did a firewall spark test to verify spark.

Not sure what else to check. The only thing i did was unplug cas to do the test and plugged it right back on after and now this.

 

[GST with PSI]

To stop it from starting.. its how i prime the turbo after a fresh install 6months ago

Just pull the MPI fuse next time. Way easier.

 

[enriquez2000]

Just pull the MPI fuse next time. Way easier.

After i figure this out i may never do a comp test again

 

[enriquez2000]

What pins on the ecu correspond to the cas? At this point i want to try checking continuity from cas to ecu to check for a break in the wire

 

[gsxeclipse102]

Pin 21 black with brown tracer and pin 22 white with brown tracer. Other 2 wires on cas should be power supply and ground.

 

[gsxeclipse102]

Ecu pinout

 

[SasaniFab]

you have the plug wires in correctly? Its usually something stupid........always in fact

 

[enriquez2000]

So white wire on connector to pin 22?

 

[enriquez2000]

you have the plug wires in correctly? Its usually something stupid........always in fact

Yes.. im swapping to my cop on it tonight and ruling out coils to be sure

 

[gsxeclipse102]

So white wire on connector to pin 22?

Yes

 

[gsxeclipse102]

Then the thinner of the two black wires to 21. The thicker black wire is a ground. Red power

 

[enriquez2000]

Then the thinner of the two black wires to 21. The thicker black wire is a ground. Red power

Power is 12v constant? Or is it a 5v

 

[gsxeclipse102]

12v key on. comes from mpfi relay.

 

[gsxeclipse102]

I dont think your going to have a problem. If you have spark cas is working. Id check mechanical timing

 

[enriquez2000]

I dont think your going to have a problem. If you have spark cas is working. Id check mechanical timing

Timing marks line up... im thinking if anything its a break in a wire since only wires touched was cas connector

 

[gsxeclipse102]

Give the wires a tug. It should be obvious if its broken. Will the car start at all anymore? After cranking are the plugs wet? Was there anything else you did while doing the compression test? Check fluids? Also chekl out the coolant temp sensor on the thermostat housing. If the connector came off or wires broke it thinks its -40 degrees.

This is deff a weird problem.

 

[enriquez2000]

Give the wires a tug. It should be obvious if its broken. Will the car start at all anymore? After cranking are the plugs wet? Was there anything else you did while doing the compression test? Check fluids? Also chekl out the coolant temp sensor on the thermostat housing. If the connector came off or wires broke it thinks its -40 degrees.

This is deff a weird problem.

Plugs are not wet.. it cranks and stumbles a bit but kind of acts like no gas. It tends to do that with e85 but after 2 or 3 tries used to fire up. Starter fluid in TB makes it attempt to start but as soon as it runs out car dies.

CT sensor is good reads 62*
Fluids are good
I checked the isc and its good
Fuel pressure is 43psi to rail
noid light shows injectors getting signal
I swapped to cop to verify coils werent the issue and put in fresh plugs(no change)
Verified 12v at cas and ground(still need to check tdc and other wire continuity to the ecu)
Timing marks line up
I also verified that injectors arent stuck by triggering them manually

I really have no clue what else to do. If it isnt continuity on cas im effed unless somehow the power transitor is the culprit but id assume no spark then.

 

[GST with PSI]

If you have spark cas is working.

^This. Same thing for fuel. If you have spark and fuel, the CAS is probably functioning as it should.

Your CT sensor reads 62*, is 62* currently ambient temp where you are?

I'm leaning toward maybe an ECU issue. I'd say pull the ECU and check the board for damage, leaking caps, or possibly a burned driver.

 

[enriquez2000]

^This. Same thing for fuel. If you have spark and fuel, the CAS is probably functioning as it should.

Your CT sensor reads 62*, is 62* currently ambient temp where you are?

I'm leaning toward maybe an ECU issue. I'd say pull the ECU and check the board for damage, leaking caps, or possibly a burned driver.

Yes its 62 out.. i can pull ecu. Was just gone over by ecmtuning about a year ago but I guess you never know

 

[gsxeclipse102]

Since it kind of stumbles when you spray starting fluid try adjusting your cold start fuel perecentage in dsmlink. Im not too good with e85 but i know it needs a lot more fuel to start. Try increasing the percentages about 10%.

 

[enriquez2000]

Im not seeing anything thay stands out to me on the ecu....

 

[GST with PSI]

How's the back side look?

 

[enriquez2000]

Sorry thought i attached it

 

[Dsmkauai]

My Miata's ecu looked perfect when i looked at it. Ended up being the only problem. Swapped another in and she's been running ever since. The old ecu would let the car start but then it would just die no matter what I tried. Got another ecu you can try? If you don't hit me up I think I have one you could use to try.

 

[enriquez2000]

My Miata's ecu looked perfect when i looked at it. Ended up being the only problem. Swapped another in and she's been running ever since. The old ecu would let the car start but then it would just die no matter what I tried. Got another ecu you can try? If you don't hit me up I think I have one you could use to try.

I have a stock one but with 1200cc injectors im not sure itll help

 

[Dsmkauai]

Swap some stock 450's in. I have those too if you might need to test. Hey didn't you say the isc or something was getting really hot? Could be a sign there's a issue with the ecu.