SIDI Hard Start Cold
  • 2009-2014 Buick Enclave
  • 2010-2014 Buick LaCrosse, Regal
  • 2012-2014 Buick Verano
  • 2013-2014 Cadillac ATS, XTS
  • 2008-2014 Cadillac CTS, SRX
  • 2008-2010 Cadillac STS
  • 2010-2014 Chevrolet Camaro
  • 2012-2014 Chevrolet Caprice, Caprice PPV, Captiva Sport, Impala
  • 2010-2014 Chevrolet Equinox
  • 2009-2014 Chevrolet Traverse
  • 2009-2014 GMC Acadia
  • 2010-2014 GMC Terrain
  • 2009-2010 Saturn Outlook
On models equipped with Spark Ignition Direct Injection (SIDI) 4- or 6-cylinder engines experiencing a hard start or extended crank condition, or black smoke from the exhaust when starting, there are several basics tests to perform during diagnosis.

First, verify fuel quality. Next, perform a compression test. On V6 engines, there should be 150–185 psi average compression. No cylinder should be less than 140 psi. On 4-cylinder engines, there should be 170–200 psi average compression. No cylinder should read less than 100 psi. Also install a vacuum gauge prior to a cold start and watch the needle for signs of a sticking valve.

In addition, perform a fuel system check. The following tests should be done after an overnight cold soak.

Set up the vehicle with the CH- 48027 Digital Pressure Gauge or equivalent and J-37287 Fuel Line with Shut-Off Valve or equivalent. Run the engine to purge all air from the fuel system and then shut off the engine and let it sit overnight. Unplug the injector harness connector.

The next morning, turn the key on but do not start the engine. Use the CH-48027 Digital Pressure Gauge or equivalent to verify prime pulse fuel pressure is between 55–60 psi.

Use the Tech 2 or GDS 2 set in PSI, confirm the fuel rail pressure sensor reading, which should always be close to what the Digital Fuel Pressure Gauge reads for low side pressure during this test. This will also confirm if there is an off-set with the fuel rail pressure sensor.

Next, crank the engine to see if it fires. With the injector harness connectors unplugged, the injectors are electrically disabled so no fuel should be delivered to the engine. If the engine fires, one or more injectors have been leaking and have introduced fuel into one or more cylinders.

Reconnect the injector harness connectors, start the engine, let it run for 10 minutes, and then shut down the engine. Close the shut-off valve in the J-37287 Fuel Line or equivalent, which will now separate the engine side of the fuel system from the rear section of the return-less fuel system.

Using the Digital Pressure Gauge, look for a drop in the high side of the fuel system by monitoring low side pressure. With the J-37287 or equivalent valve closed, the system should hold at least 60 psi for a few hours. If there is a rapid decrease in fuel pressure, this would indicate a leaking high pressure fuel pump or leaking injectors since the fuel pressure cannot bleed off to the tank as the fuel line shut-off valve is closed.

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