no start... how to troubleshoot?
 

Hi guys,

I put the car together after a TB change and turbo install and can't get ignition

Quick summary of events:
- when cranking, no ignition
- tested compression, 170 on cyl 1, 180 on others
- tested spark but possibly not correctly? Pulled plugs out of the engine but kept attached to coil, grounded plugs individually and cranked the car to see if any sparks would fire, no fire
- when plugs came out, they were not "wet" with fuel though with the fuel fuse in, they pump seems to prime - not sure if injectors firing
- previously car started and drove just fine on the NA base tune pre-turbo.
- I removed PS and just left the PS wire "dangling" - my understanding is this is a signal wire.


- how can I check crank angle and cam angle sensor in megalog viewer? some posts suggest that if these are not working there will be no fuel.
- will seeing cam and crank positions help verify if I did my TB install right? I worry i may be off a tooth though I triple checked when installing.
- could my coil be fried from dry firing (compounding the no-start issue)?
- any "typical" grounding issues? will need to check again if anything was unplugged accidentally.



- pretty lost

sounds like your cam/crank position is disconnected. What year?

Hi Seefo, it is a 96 1.8. Both are "connected" in the sense that I plugged them in but what is a good way to test for proper function? I've seen some voltage tests for the cam angle sensor but not sure how to test the crank.

Not sure how in megastudio. you will have to wait for a megasquiet guy to come around.

Your coils will be fine as long as the plugs are connected.

Go into Tuner Studio and do a Composite Log while cranking.

Thanks, I didn't know how to do that... Here are my logs, two separate CSVs capturing cranking at about 5 seconds on / 5 seconds off.... as far as I can tell, it looks like crank position and cam position are working? Is there a way to get additional layers of information such as ignition signal etc?

Also, does the DIYPNP need this fuse out (10 Amp, bottom right corner when standing on passenger side, facing engine)

MX-5 Unleashed - Mega Squirt PNP installation instruction for Eunos or miata

csvs:

https://www.dropbox.com/s/clafoqy7yb...45.27.csv?dl=0
https://www.dropbox.com/s/6he3hmdc0g...47.12.csv?dl=0

well... In Megalog viewer I am seeing PriLevel and Toothtime as oscillating signals - which is which? Toothtime oscillates and then spikes?

Prilevel alternates between 0 and 1 but is not a clean "square" signal.

I don't have any data for "Trigger".

I always thought the stock crank signal should be "square". which signal am I missing?

I don't have a way to "trim" a resistor to get a good signal from my hall sensor on my DIYPNP - am I seeing a calibration issue that can be resolved another way?

No crank signal - with 36-2 trigger wheel - MX-5 Miata Forum

From Matt Cramer:

The ST SIG fuse is ONLY for the 1.6 Miatas that use the air flow meter to control the fuel pump. It is because we had to come up with a work-around to allow the ECU to control it.

The composite logs show a crank signal but no cam signal. If you are using a DIYPNP, MS3 directions will not apply to you. Please be sure you have a 5 volt pull up in place on VR2 and do not have R20, R21, or R39 installed.

I took several hours over the weekend I tried to isolate the crank and cam signals. Still no start - anyone any suggestions?

Here is a summary of what I've done to the car. It turned out the signal I was getting was from the Cam (plugging and unplugging made it appear and disappear). I also traced the wiring from the Crank to the ECU and they are not jumpered - 4E and 4H. Now questioning if I ever had crank signal previously when I ran the car in naturally aspirated form. I also realized I made a blunder trying to use a 9495 turbo tune on a 96 as pins have changed - previously improperly assumed that only differences were in displacement. :facepalm:

Baseline:

Car is a 96. Ran on DIYPNP prior to turbo install and TB change. After install, had a 25V capacitor explosion. replaced caps, re-wired trace. Replaced capacitors with digikey 39-3595-ND, loaded firmware 331a, plugged back into car. Car cranks, but no start. 22F ambient temperature.

Condition 1 (last week):
Loaded the 9495 331a turbo tuner map. Cranks, no start.
Tests / assumed results:
- only got one signal in composite log viewer (Trigger) / assumed it was crank
- per matt, confirmed a 470 pullup in for VR2, I don't have R20,21,or 39 installed
- tested voltage from cam harness, returns were 0,+11.8,+10,5 when key in "on position" (when harness tab is facing up, left to right)
- tested cranking with cam plugged in and unplugged - signal went away when unplugged. have - signal is CAM not crank.


Condition 2 (this weekend):
- confirmed gap on hall sensor to crank tooth
- tested proper resistance on hall sensor (500Ohm)
- confirmed continuity and resistance from crank sensor at ECU. (4E and 4H)
- 4E and 4H are not jumpered in so I guess I never got a crank signal?

This is when I realized the 94/95 used different jumpers than a 96. I loaded up the 96 NA tune base map.

Tests/Results:
- tunerstudio still says "not synced"
- when logging, unable to save a composite log at all as tunerstudio says "no signal received from controller"
- I think hardware wise, the sensors are fine and that they are properly connected to the ECU harness.

Questions:
- Does the 96 need a crank signal? (Instructions show no jumpers on 4E or 4H where crank signals go)
- Why am I now unable to see a cam signal at all? Seems like all physical wiring/harnesses are fine and a CAM signal was present when (improperly) using the 9495 tune file.
- Am I getting correct voltages out of the DIYPNP into the cam sensor?
- n00b confirmation: which firmware should I use for the DIYPNP? (I am using the "Microsquirt-module" option when loading 331A. Didn't use 333 because I could not find a turbo 9697 tuner map.
- what else can I check?

-getting pretty frustrated...

continued diagnosis:

https://www.dropbox.com/s/iqt7zr16dw...pture.PNG?dl=0

When checking on the DIYPNP while probing GND with - and 5V power with + (not vref) I am also getting 50mV instead of 5V. This leads me to suspect that something else other than C1 and the trace was damaged as a part of the over-voltage explosion.

How can I diagnose U5? When doing simple connectivity testing from + on C1 to diodes near U5 and pins on U5, connectivity changes when plugging in and unplugging a 12V bench power supply. I know the narrative is a bit simplistic but does this adequately suggest that U5 is "working" when power is supplied?

What else could be happening that I'm not getting 5v?

Well, did lots of testing and went back and forth with Matt over at DIYAutotune. The Crank angle sensor was fine but I had a short on U5 caused by too much thermal compound which effectively dropped the 5V regulated voltage down to 50mv. After clearing away the compound, the engine fired right up - Thanks Matt!