Ok, my mechanic found that the intake valves on the same cylinder as mentioned in previous post were not seeding . Could this be a coincidence or is the open valves causing the coil pack not to fire. Please note that the coil pack works if swapped to other cylinders.
Found this online
When checking for the coils closing, you should always check with the engine cranking for reliable results; testing them static is not reliable.
That being said, with only one coil firing, ruling out any foul play (rodent damage to wiring etc), there are only two typical causes for this condition. Either a timing relationship issue (either actual timing mismatch or falsely interpreted as such) or a blown driver for the coil.
When one circuit goes dead (one coil won't fire, and swapping coils does not change the condition), it is due to a lack of signal from the PCM to fire the coil.
If there is a problem with the belt timing, the PCM will only fire one coil repeatedly and will never engage the second coil; this is to shut down the engine in the event of a belt failure to try to prevent valve damage running the engine out of time.
This condition can be caused by either the timing belt being off a tooth or more, or you can have a faulty camshaft position or crankshaft position sensor feeding erroneous information to the PCM, causing it to shut off the single coil. Obviously at that you would want to start by checking your cam and crank alignment on the timing belt, and verifying your cam and crank sensor outputs (primarily the cam sensor though... crank sensor is more common to drop spark altogether, whereas the cam sensor is more likely to send erroneous information and shut down one coil).
If the belt timing is OK and the cam and crank sensors both check out all right, then you will be looking at something a bit more sinister. The drivers for the two coils are located inside the PCM on this vehicle, with no external failure sensor or igniter pack. This is unfortunate as it makes for an expensive repair if the drivers go bad. The drivers send a low voltage output to each coil (300mV-3V max) to trigger the internal transistor to ground the coil. If this signal is not present at the coil, it is a direct run to the PCM... so ruling out any wiring damage, if the belt timing and crank/cam sensors are OK, the next stop is rebuilding or replacing the PCM.
While it is not terribly common for these drivers to fail, when they do it is normally due to a faulty ignition coil. We see a large number of PCM failures within a few thousand miles of aftermarket coil pack installation. This is due to poor quality control on these coils allowing voltage bleed internally, sending high voltage (12V) back down the 3V max driver line, burning out the driver.
The PCMs do fail on their own, it isn't too common though compared to the aftermarket coil scenarios.
Start with the belt timing and cam/crank sensor inspections first. If they turn up OK it will likely be PCM time. Be aware that the immobilizer key information is stored in the PCM on this model, so you can not just put a new/used PCM in, you need to reprogram the keys to the new PCM when it is changed.
When checking for the coils closing, you should always check with the engine cranking for reliable results; testing them static is not reliable.
That being said, with only one coil firing, ruling out any foul play (rodent damage to wiring etc), there are only two typical causes for this condition. Either a timing relationship issue (either actual timing mismatch or falsely interpreted as such) or a blown driver for the coil.
When one circuit goes dead (one coil won't fire, and swapping coils does not change the condition), it is due to a lack of signal from the PCM to fire the coil.
If there is a problem with the belt timing, the PCM will only fire one coil repeatedly and will never engage the second coil; this is to shut down the engine in the event of a belt failure to try to prevent valve damage running the engine out of time.
This condition can be caused by either the timing belt being off a tooth or more, or you can have a faulty camshaft position or crankshaft position sensor feeding erroneous information to the PCM, causing it to shut off the single coil. Obviously at that you would want to start by checking your cam and crank alignment on the timing belt, and verifying your cam and crank sensor outputs (primarily the cam sensor though... crank sensor is more common to drop spark altogether, whereas the cam sensor is more likely to send erroneous information and shut down one coil).
If the belt timing is OK and the cam and crank sensors both check out all right, then you will be looking at something a bit more sinister. The drivers for the two coils are located inside the PCM on this vehicle, with no external failure sensor or igniter pack. This is unfortunate as it makes for an expensive repair if the drivers go bad. The drivers send a low voltage output to each coil (300mV-3V max) to trigger the internal transistor to ground the coil. If this signal is not present at the coil, it is a direct run to the PCM... so ruling out any wiring damage, if the belt timing and crank/cam sensors are OK, the next stop is rebuilding or replacing the PCM.
While it is not terribly common for these drivers to fail, when they do it is normally due to a faulty ignition coil. We see a large number of PCM failures within a few thousand miles of aftermarket coil pack installation. This is due to poor quality control on these coils allowing voltage bleed internally, sending high voltage (12V) back down the 3V max driver line, burning out the driver.
The PCMs do fail on their own, it isn't too common though compared to the aftermarket coil scenarios.
Start with the belt timing and cam/crank sensor inspections first. If they turn up OK it will likely be PCM time. Be aware that the immobilizer key information is stored in the PCM on this model, so you can not just put a new/used PCM in, you need to reprogram the keys to the new PCM when it is changed.
Please start your own thread, it's no use hijacking another thread and taking it off topicSadeq wrote:Good Evening i own a 99 3.5 DOHC i have a big problem. There's no spark on coil pack 3. I changed the Crank sensor, Crank Sensor Plate, Ignition Module, Coil Pack, ECU, Transponder, Transceiver, Barrel & Key. I Found the knock had a broken wire gonna replace it the weekend. Has anyone had such a problem before, Please help i'm at my wits end. Diagnostics not very helpful.
Is it possible that the knock sensor can cancel out a cylinder.
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