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Old 08-05-2011, 01:36 PM   #1
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Unhappy replaced power TR unit now car wont start

i replaced my power TR unit on a 1990 miata, when i was done it started right up. when i came back to the car it would no longer start. im running megasquirt pnp and i didnt disconnect the battery when replacing the power TR unit. i have spark and fuel, but the injectors are not firing. any ideas? im stomped
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Old 08-05-2011, 01:46 PM   #2
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power TR?
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Old 08-05-2011, 01:53 PM   #3
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Power Transistor, aka igniter module.
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Old 08-05-2011, 02:04 PM   #4
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if you have spark and fuel, the ignitor is working.
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Old 08-05-2011, 02:08 PM   #5
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i have fuel to the fuel rail, but the injectors are not firing
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Old 08-05-2011, 02:09 PM   #6
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and it was right after replacing it, the car wouldn't start.
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Old 08-05-2011, 02:15 PM   #7
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Quote:
Originally Posted by Braineack View Post
if you have spark and fuel, the ignitor is working.
Ftfy.
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Old 08-05-2011, 02:23 PM   #8
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i replaced the injector relay also. any ideas on what could go bad, that would prevent the injectors from opening.
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Old 08-05-2011, 02:32 PM   #9
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are they getting 12v on the white/red wires?

otherwise the MS grounds them. Fuel pump running?
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Old 08-05-2011, 02:34 PM   #10
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could i have fried something in megasquirt
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Old 08-05-2011, 02:35 PM   #11
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yes the fuel pump it running
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Old 08-05-2011, 02:36 PM   #12
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im going to check right now, the wires to the injectors?
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Old 08-05-2011, 02:49 PM   #13
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The wiring of the fuel system is fairly simple:



+12 volts comes out of the Main Relay on the white/red wire when the key is on. The voltage then goes to the fuel injector harness (still red/white) and hits one side of each injector.

The other side of each injector goes back to the ECU- they're wired in pairs, so two wires, one yellow, the other yellow/black. The ECU closes those wires to ground, completing the current path through the injectors, when it wants them to fire.

We know the Main Relay is working, as the same white/red wire also supplies power to the ECU and several other things.

Look at the injector duration on the Megasquirt, either by logging it while you crank it or by setting one of the Megatune gauges to read Pulse Width 1. Is the MS even trying to squirt? Also, in MegaTune, do you see a believable coolant temperature reading when the system is on? It should read somewhere near ambient.
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Old 08-05-2011, 03:43 PM   #14
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ok, i tested the red/white wire. it has 11.4v, also have full fuel presser. i was able to start it with brake cleaner, which tells me im not getting fuel.
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Old 08-05-2011, 04:02 PM   #15
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take a log while cranking, post.
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Old 08-05-2011, 05:01 PM   #16
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im having trouble connecting to megasquirt, ill have my tuner try and log it for me, would a bad cam angle sensor stop the injectors?
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Old 08-05-2011, 05:27 PM   #17
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I'd like to add that we accidentally put fuse in the ST connector a few weeks ago and blew the Q5 transistor, pman ordered a new one from diyautotune & I installed it last night so the fuel pump turns on now - data log coming in 30 minutes I'm gong over to his house with my netbook to log the cranking, we just went and got it connected and datalogged cranking so the info is coming shortly

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Old 08-05-2011, 06:58 PM   #18
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I attached a trigger log & datalog of our cranking from just a few hours ago, any insight ?
Attached Files
File Type: msl triggerlogs.msl (21.9 KB, 138 views)
File Type: csv augusttroubleshooting2.csv (55.2 KB, 88 views)
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Old 08-06-2011, 04:42 PM   #19
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Any ideas?
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Old 08-06-2011, 05:21 PM   #20
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Is the map loaded inside the ECU ok? I see from your log that your cranking pulsewidth is about 1.5ms - that doesn't seem right.
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megasquirt ms ms1 ms2 ms3, not starting, power tr unit, starting

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