The absence of a CKP relearn will cause the flashing warning light, engine no longer knows where TDC is for ignition and injector timing

Neal

 

thanks Neal. That’s exactly what I have scheduled at the shop. Closest one charges $125 vs a dealership asking for $175. I may invest in a good tool in the very near future.

let ya know how it goes.

 

Agreed - the P0300 is almost certainly caused by the new crank sensor. Probably getting some spark knock as well since without that crank sensor being learned the timing is all jacked up.

In the eSI system for P0300...

"System Description
The powertrain control module (PCM) uses information from the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If the PCM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 will set.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0300 Engine Misfire Detected

Conditions for Running the DTC
• DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0125, P0128, P0220, P0315, P0335, P0336, P0341, P0342, P0343, P0502, P0503, P1114, P1115, P1120, P1258 are not set.
• The engine speed is between 450-5,000 RPM.
• The ignition voltage is between 10-18 volts.
• The engine coolant temperature (ECT) is between -7 and +130°C (+19 and +266°F).
• The fuel level is more than 10 percent.
• The throttle angle is steady within 1 percent.
• The antilock brake system (ABS) and the traction control system (TCS) are not active.
• The transmission is not changing gears.
• The A/C clutch is not changing states.
• The PCM is not in fuel shut-off or decel fuel cut-off mode.
• The PCM is not receiving a rough road signal.
• DTC P0300 runs continuously once the above conditions are met.

Conditions for Setting the DTC
The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.

Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
• Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration:
- Thickness variation of the brake rotors--Refer to Symptoms - Hydraulic Brakes in Hydraulic Brakes.
- The drive shaft not balanced--Refer to Vibration Analysis - Driveline in Vibration Diagnosis and Correction.
- Worn or damaged accessory drive belt--Refer to Symptoms - Engine Mechanical in Engine Mechanical - 4.8L, 5.3L and 6.0L.
• There may be more or less cylinders actually misfiring than indicated by the scan tool.
• Spray water on the secondary ignition components using a spray bottle. Look and listen for arcing or misfiring.
• If there are multiple misfires on only one bank, inspect the fuel injector and ignition coil, power and ground circuits for that bank. Refer to Engine Controls Schematics."

 

Good info. Appreciate it.

does that mean I need to tow the truck to the shop or can I do a 3 mile trip at slow speed? The light is solid until the truck hits about 25-30 miles.

 

Get a quality scanner! Then you can check o2's v readings .01-1v. You can also remove and bench test them, yet easier with a scanner.

 

Solid is ok for a short trip, flashing is NOT good.

 

Great thanks. Will update sometime Friday.

 

The flashing light is the PCM telling you that it thinks that the PCM is over fueling to a point that could cause immediate damage to the CAT's.

This is a function of the PCM not knowing exactly where TDC is and the injector timing possibly being off enough to cause the damage.

Let the truck warm up fully prior to driving and then take it easy on the drive to the shop, if you can feel any odd surges or anything out of the ordinary while driving then try slowing down a little.

You should be able to drive it to the shop, I've had the light flash a few times after doing some mods to trucks prior to doing the crank relearn and never really felt any issues with the way the truck ran and no damage was done to the CAT's.

Neal

 

Ok quick update. Did a lot of tests on my own as an exercise and to learn how to trouble shoot. Tested O2 sensors, fuel injectors and connectors, verified some values, traced wiring. Did that with a standard multi meter, bought a cheaper version tester for home which btw works great for what I need atm. It’s the ATL519 OBD2 reader. In all I had the P0200 and 0300 codes. Had an idea of where the issue is and it was verified by a mechanic which came over to do his diagnostics. He also did the crankshaft relearn afterwards.

Both down stream O2 sensors were toasted. Had a misfire on cylinder 5. didn’t realize the spark plug wasn’t all the way in. He pointed that out to me. Dugh. Not having the relearn contributed to the blinking engine light as some pointed out. Thanks for the info on that.

after clearing the codes he did the relearn and it’s running ok thus far.

i am very happy with the mechanic (mobile). Straight to the point and honest and charged me less than quoted and way less than anyone I called at the shop or dealership. I’m still in shock. He will definitely get more business from me.

Next up new exhaust and at some point need to do the rear seal. Ah the fun never ends. Cheers

 

do your own relearns, i bought this gadget and love it.