Crank no start, backfires on crank

Hi,

Does this happen on one or all fuel injectors? Have you checked the ASD relay also?

I ask because the PCM provides battery voltage to each injector through the ASD relay. Injector operation is controlled by a ground path provided for each injector by the PCM. Here is where I would start. Switch the ASD relay with one having the same part number in the fuse/relay box. If there isn't one, here is a link that explains how to test a relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If you look at pic 1 below, it shows the location of the ASD in the power distribution box under the hood.

Check this and let me know what you find.

Take care,

Joe

See pic below.

The idea that you lose the injector pulse should shut the engine down. Often times, backfiring is caused by too much fuel getting into the engine. Do me a favor and take a look through this link. It describes how to identify and repair a backfire. See if anything helps.

https://www.2carpros.com/articles/engine-backfires-while-running

Also, I need for you to check the ASD relay. It's located in the under-hood power distribution box. I attached a picture above identifying its location.

Switch it with another relay having the same part number or you could follow the link I attached above.

Let me know the results.

Joe

Hi,

Does the Blue-driver have a live data setting? If it does, check to see if there is an RPM signal being generated by the crankshaft position sensor. The PCM uses crankshaft position reference to determine injector sequence, ignition timing, and the presence of misfire. Once the PCM determines the crankshaft position, it begins energizing the injectors in sequence. Something could be failing there. The only thing that confuses me is the idea that it has spark.

When the key is in the ON position and the engine is not running (zero rpm), the Auto Shutdown (ASD) and fuel pump relays de-energize after approximately 1 second. Therefore, battery voltage is not supplied to the fuel pump, ignition coil, fuel injectors, and heated oxygen sensors. So, if you have spark, the sensors should be working. That leaves a wiring problem or a PCM problem.

If you can check for an RPM signal, let me know. If not, we need to start at the injectors and work backward. I would really like to know if all the injectors are doing the same thing. That could help eliminate possibilities.

I attached the wiring schematic below for the entire powertrain management system. I need you to locate the brown wire with a white tracer at each injector. There is a wire splice near the breakout for injectors 5 and 6. Inspect that splice for corrosion or damage.

If it is good, we need to work back to another wire splice which is large. See the schematic. I circled both splices to check. Make sure the same thing is there, no corrosion, and in good condition.

Let me know what you find.

Let me know.

Joe

See pics below. Note: I had to cut each page of the schematic in half to make them readable for you. I did overlap them so you can follow from one to the next. I highlighted and wiring involved. Note that the splice sends power to several different components (S112) which is near the IPD module under the hood.

Hi,

If you have power to each injector, then either there is a bad connection at the PCM, a wiring issue (unlikely if they all lose pulse), or a possible PCM issue.

Before we jump to that, have you inspected the camshaft position sensor? If not, check that connector. See pic 1 for location.

If that appears good, I need you to disconnect the battery. Then, disconnect the connector at the PCM and check for corrosion, damaged pins, or anything that could cause a problem. See pic 2 for location.

Let me know what you find.

Joe

Hi,

If everything is good, then the problem must be the PCM itself. Have you checked for an injector pulse right at the PCM? If you lose it there, then chances are the PCM is the issue.

Remember, the PCM provides power to the injectors via the ASD. Then, based on input from the CKP and CMP sensors, along with other sensors, the PCM provides a ground path. So, make sure the ground (where the PCM mounts) is in good condition.

Let me know.

Joe