Intermittent Long cranking times before firing
Vehicle data: 12/07 Honda Accord, 2.4 L DOHC, auto transmission.
Approximately 2 or 3 times a week there will be extended cranking time before firing. These extended times are about 3 or 4 times normal cranking time before firing. With some of these extended cranking times the yellow engine light comes on. This light will go out after a day or 2.
On 2 occasions the car went into "limp home mode". In this condition the car would struggle to achieve 40 km/h and have very little power. This condition occurred the first time after extended cranking. The 2nd occasion was whilst driving: the engine started normally but at about 30 km/h power was lost and a maximum speed of 30 to 40 km/h was all that could be achieved.
Diagnostic scan results: P0339 CKP sensor circuit intermittent interruption; P0302 misfire #2 cylinder; P0303 misfire #3 cylinder; P0300 random misfire; anti-lock brake code- 83-13 ECM/PCM relation failure.
In an attempt to solve this issue I have changed the CKP sensor, changed the in tank fuel filter, drained and cleaned the fuel tank and tested fuel pressure. As codes were thrown up for number 2 and number 3 cylinders, coils and plugs were swapped with 1 and 4 cylinders. All these measures have not resolved the extended cranking times. And we are waiting for the vehicle to go into its 3rd "limp home mode".
After this work was carried out I consulted a Honda dealer with vehicle specific diagnostics. The vehicle was off the road at the dealer for a week and a half with no resolution as the fault conditions that existed in the vehicle on arrival disappeared after about 4 days and for the remaining time the vehicle functioned normally. The Honda technician was working through a checklist and when that checklist failed to fix the problem the next stage was to get from Honda Australia a test ECU. But they could not tell me when this would be available and didn't seem very interested in pursuing the problem further. They said if I brought the vehicle back they could only do what they had done previously that was unsuccessful. In addition to that they seem to blame the age of the vehicle and what put me off even further was when they said I wasn't a regular customer. So I felt quite abandoned.
During their investigation they failed to: check the CKP sensor wiring for continuity back to the ECU; did not check the waveform or the amplitude of the hall effect CKP sensor output nor did they check the plug connections at the back of the ECU. That seems to me to be a major failure in diagnostics given the problem was intermittent.
At this stage I am wondering whether there are any other sensors that combine with the CKP sensor to get the engine to fire normally. There could be a deterioration or an intermittent fault on one or more of these.
I really hope you can shed some light on this problem.