Hey man how are ya?
I got a 99 Vette C5 coupe, 80k on the clock, manual, 5.7L V8, Borla axle back exhaust
I punched it out of the driveway and she just bogged down loss of power running real rough check engine light came on
Throwing P0200, P0300, so I decided to change the plugs, wires and whatever coil I needed to change Bc everything was original.. So plugged the computer back in kept coming up #1 was erratically misfiring the number kept going up n down.. I changed the coil same thing (has new plug n wire).. They’re 4 pin coil packs.. Then I was thinking it might be the power to the coil but can’t find a video on how to check voltage in that male plug.. Think I got a vacuum leak also behind the intake manifold… Need help.. Thanks
Ignition Positive Voltage goes to all of the coils on the Pink wire on the end of the coil wiring connectors. (pin D).
To test for battery voltage there, unplug the connector, grab a test light and hook the alligator clip onto the battery negative post.
Turn the ignition key to the ON position and touch the test light probe to the wiring connector terminal for the Pink wire.
If there's power going to the connector the test light will illuminate.
Here's how that #1 ignition coil is wired:
You can also just grab an HEI Spark Tester at the auto parts store and test the spark from that coil too. That will tell you if the Ignition Positive Voltage, Ignition Control Signal, Low Reference (Computer Ground), and the Engine Ground (G107) are all good.
You can't ignore the P0200 fuel injector circuit code. That could be the problem. Maybe check the 2 wires at the cylinder #1 fuel injector connector. They can get brittle and break with age. They sometimes break but the wiring insulation stays intact so you don't see it. Grab the wires and give them a gentle tug. If one of them is broken inside the insulation the wire will come apart. Then you just replace the wiring connector with a new pigtail and you're good to go. Also, you can use a multimeter to measure the resistance between the 2 fuel injector terminals to determine if the fuel injector itself is faulty.
Lastly, you know you have a vacuum leak. That could be causing the misfire.
