Hier is een procedure m.b.t. 'mogelijkheden':
The Procedure:
1) Check OCV Filter, Clean as Necessary, re-test drive vehicle prior to Step 2.
2) Check Operation of OCV Valve: (Engine must be fully warmed up)
a) PASS: Unplug OCV connector - idle should not change
b) Connect 12V DC across OCV terminals after step 2a:
i) PASS: Engine Stalls or almost Stalls when voltage manually applied to OCV Valve terminals, No Change to idle when OCV disconnected from plug - Go To Step 3
ii) NP(Bad): No Change to idle when Voltage Manually applied to OCV Valve, or large change in idle when OCV Valve disconnected from plug at idle- Replace OCV, Plunger/Solenoid not operating
3) Check Signal from ECU to OCV Valve Plug (may unconnect or tap into wires)
a) PASS: Pulse-Modulation Signal changes with Engine RPM Go to Step 4
b) NP: Pulse-Modulation does not change or no Pulse-Modulation Signal from ECU to OCV Valve plug - Go To Step 5
4) If Steps 2 & 3 Pass Replace VVTi Cam-Actuator:
a) Remove Timing Belt, remove VVTi Cam, Clean Cam Oil Journals, Replace Cam-Shaft Seal, Install new VVTi Cam
b) Test Drive, if replacing OCV Valve & VVTi Cam have no effect move to Step 5
5) Check Signal from Cam-Shaft Sensor (this obviously could be done as Step 2, but the general idea is that if there is a pulse-modulation signal coming from the ECU, then it must be deriving that signal from the Cam-Shaft Sensor)
a) PASS: Signal Sent changes with RPM - Go to Step 6
b) NP: Inconsistent or Non-Existent Signal: Replace Cam Shaft Sensor
6) Check ECU:
a) PASS: Signals from both Camshaft wires and OCV Valve consistent at ECU and at sensor & OCV Valve (in other words check the signals at the wires directly at the ECU AND tat the sensor and OCV Valve - there may be an intermittent break in the wires causing intermittent incontinuity of signal while driving) - Go to Step 7
b) NP: Replace Wire Harnesses between ECU and Sensor and ECU and OCV Valve - Re-Test Drive
7) Check Cam-Shaft and OCV Housing Oil Journals & Oil Presure
a) Disassemble Timing Belt, VVTi Cam Assembly, remove Intake Valve cover, remove all Camshaft Bearing Caps and inspect for excess wear, clean all internal oil passages.
b) Check Oil Pressure on Supply Line to OCV Valve (requires some special equipment to keep oil from spraying everywhere) - You can also do this by removing the OCV Valve putting a towel in its place and turning over the engine for a few cranks, oil should come out pretty fast, and will make a mess.
i) PASS: Oil Pressure supplied to OCV & Cam Journals free of blockages and Camshaft Bearings good - Go to Step 8
ii) NP: Replace all worn or inoperative parts, including Oil pump if Oil starvation is noted.
8) Replace ECU
Notice Replacing the ECU is Dead-Last...just after taking apart the entire upper end. Its pretty much a common-sense Logic process eliminating the most common/easiest to cure sources of the problem. My hunch is if Steps 1-8 dont work, the engine is "worn-out" and may have some sticking valves or other issues sending bad signals to the ECU which could take days upon days to trace and track...which is why in these instances dealers replace entire motors...the motor may cost less than the labor when all else fails.