No pulse to #3 code p0203

[XLexusTech]

LS3 Crate motor, PSI harness and ECU. Car starts and but run throws a p0203. Checked injector signal with node light no pulse header tube is cool on #3
12Volts to the pink wire at injector key on and while running.

I assume the only thing that could cause is this break in the ground side (tan) bad connection to pin 38 on X2 (GRAY) or a bad ECU..

If I am on the right track then Ohm out the tan wire to the pink / black in pin 38? If good then it must be ECU ?

[Tim C]

Ohm out the wire itself and also make sure it doesn't have voltage or a ground with both ends unplugged. If it does you'll need to find the short to voltage or ground or the break if it's open. You can also check the wire coming directly out of the ecm with a backprobe to see if it is pulsing there. If you have 12v at the injectors and the ground wire is good but there's no pulse it's likely an injector driver in the ecm if that's the only code you have. Some ecms will disable the injector if the coil is throwing a code or if it shows a misfire code, mostly to protect the catalyst but I'm not sure if that's disabled on your setup or not.

[XLexusTech]

Ohm out the wire itself and also make sure it doesn't have voltage or a ground with both ends unplugged. If it does you'll need to find the short to voltage or ground or the break if it's open. You can also check the wire coming directly out of the ecm with a backprobe to see if it is pulsing there. If you have 12v at the injectors and the ground wire is good but there's no pulse it's likely an injector driver in the ecm if that's the only code you have. Some ecms will disable the injector if the coil is throwing a code or if it shows a misfire code, mostly to protect the catalyst but I'm not sure if that's disabled on your setup or not.

Thank you Tim, so update: OHM test was good. Back probe was good with a test light saw flicker at pin # 38 of the ECU. Then retested with node light and it started working. But the header pipe was still cool ... pulled the plug, found a crack in the porcelain. Changed the spark plug.. boom nice color on the Exhaust Pipe.
Then #8 started same problem no light at injector... I figured messing with the connector may have disturbed connections.

cleaned reseated then 8 lites up the noide light. Still doesn't feel like its running on all 8 though.

P0141 and p0171 and p0174 .... One o2 is pinned at .45 the other cycles between .90 and .04

188484188483188482

[Hotwire]

Do you know if the engine has sat with fuel in the rails? Ethanol will stick the injectors quicker than you'd imagine, have had my share of issues with them.

One thing to try if you have a fuel pressure gauge. Install it, prime system by cutting key on, then pull fuel pump relay, fire the car and watch the fp gauge. The needle should bump down incrementally with each cylinder firing like a stop watch. If the needle hesitates or doesn't tick down consistently you have an injector stuck closed/not firing.

[XLexusTech]

Thanks for the reply. No motor never had fuel in it. I have a gauge but not sure its good enough for this test.



Do you know if the engine has sat with fuel in the rails? Ethanol will stick the injectors quicker than you'd imagine, have had my share of issues with them.

One thing to try if you have a fuel pressure gauge. Install it, prime system by cutting key on, then pull fuel pump relay, fire the car and watch the fp gauge. The needle should bump down incrementally with each cylinder firing like a stop watch. If the needle hesitates or doesn't tick down consistently you have an injector stuck closed/not firing.