Ignition Question
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Laughing Gas
Joined: Jan 2006
Posts: 1,098
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From: Minnesota
Ignition Question
I tried to search but came up with nothing. I was wondering if someone would be willing to post or direct me to a previous post on how the ignition system works on my 98 F-150 4.6. I'm curiuos on the sequence of events and specific sensors that all come together to start the vehicle. It looks kind of straight forward but I don't see a specific spark module like on other vehicles I have worked on. I loaned my book to my son (at college) yet to get it back! I just want to be prepared for a possible no spark- no start situation. Thank you in advance!
Spotty..
Spotty..
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Joined: Aug 2002
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From: BC, Canada
I can't recall ever seeing a no spark situation on one of these trucks. They don't have a seperate module like the older ones did. It's all in the PCM (Powertrain Control Module).
From the manual.............
The Integrated Electronic Ignition (EI) system consists of a crankshaft position (CKP) sensor, coil pack(s), connecting wiring, and PCM. The Coil On Plug (COP) Integrated EI System uses a separate coil per spark plug and each coil is mounted directly onto the plug. The COP Integrated EI System eliminates the need for spark plug wires but does require input from the camshaft position (CMP) sensor. Operation of the components are as follows (Figure 50) :
Note: Electronic Ignition engine timing is entirely controlled by the PCM. Electronic Ignition engine timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.
The CKP sensor is used to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted to the crankshaft. The CMP sensor is used by the COP Integrated EI System to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.
The PCM uses the CKP signal to calculate a spark target and then fires the coil pack(s) to that target shown in Figure 51. The PCM uses the CMP sensor not shown in Figure 51 on COP Integrated EI Systems to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.
The coils and coil packs receive their signal from the PCM to fire at a calculated spark target. Each coil within the pack fires two spark plugs at the same time. The plugs are paired so that as one fires during the compression stroke the other fires during the exhaust stroke. The next time the coil is fired the situation is reversed. The COP system fires only one spark plug per coil and only on the compression stroke.
The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, battery positive voltage (B+) applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, the power is interrupted and the primary field collapses inducing the high voltage in the secondary coil windings and the spark plug is fired. A kickback voltage spike occurs when the primary field collapses. The PCM uses this voltage spike to generate an Ignition Diagnostic Monitor (IDM) signal. IDM communicates information by pulsewidth modulation in the PCM.
The PCM processes the CKP signal and uses it to drive the tachometer as the Clean Tach Out (CTO) signal.
From the manual.............
The Integrated Electronic Ignition (EI) system consists of a crankshaft position (CKP) sensor, coil pack(s), connecting wiring, and PCM. The Coil On Plug (COP) Integrated EI System uses a separate coil per spark plug and each coil is mounted directly onto the plug. The COP Integrated EI System eliminates the need for spark plug wires but does require input from the camshaft position (CMP) sensor. Operation of the components are as follows (Figure 50) :
Note: Electronic Ignition engine timing is entirely controlled by the PCM. Electronic Ignition engine timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.
The CKP sensor is used to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted to the crankshaft. The CMP sensor is used by the COP Integrated EI System to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.
The PCM uses the CKP signal to calculate a spark target and then fires the coil pack(s) to that target shown in Figure 51. The PCM uses the CMP sensor not shown in Figure 51 on COP Integrated EI Systems to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.
The coils and coil packs receive their signal from the PCM to fire at a calculated spark target. Each coil within the pack fires two spark plugs at the same time. The plugs are paired so that as one fires during the compression stroke the other fires during the exhaust stroke. The next time the coil is fired the situation is reversed. The COP system fires only one spark plug per coil and only on the compression stroke.
The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, battery positive voltage (B+) applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, the power is interrupted and the primary field collapses inducing the high voltage in the secondary coil windings and the spark plug is fired. A kickback voltage spike occurs when the primary field collapses. The PCM uses this voltage spike to generate an Ignition Diagnostic Monitor (IDM) signal. IDM communicates information by pulsewidth modulation in the PCM.
The PCM processes the CKP signal and uses it to drive the tachometer as the Clean Tach Out (CTO) signal.
Thread Starter
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Laughing Gas
Joined: Jan 2006
Posts: 1,098
Likes: 11
From: Minnesota
Thanks Racerguy!.... Sounds like a good setup, not too complex. I know this isn't a Mustang forum but I have a 97 Mustang Gt, black on black, I only drive on nice weekends. I have left it 100% stock but my kids want to get me a chrome shift **** for Christmas( I have the 5-speed stick). Is there a lock nut under the boot that keeps the shift **** on? Thanks again for a great response on the ignition question...
Spotty..
Spotty..
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Joined: Jan 2004
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From: St Louis
Note that the 98 4.6 is NOT a COP system, it is a dual coil pack system.
Check fuse F30 in the underhood fusebox. If blown, you loose power to the coils. Most common cause of a blown F30 is a shorted RFI cap. There is one next to each of the coils. If shorted, just disconnect it until you get around to replacing it, they're not important for engine operation (RFI suppression).
Steve
Check fuse F30 in the underhood fusebox. If blown, you loose power to the coils. Most common cause of a blown F30 is a shorted RFI cap. There is one next to each of the coils. If shorted, just disconnect it until you get around to replacing it, they're not important for engine operation (RFI suppression).
Steve
