1997 after mkt. tack problem
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Which motor do you have/
.
Problem is today's engines use multiple coils or coil packs.
Sampling from one pack would be at the wrong frequency for Tach accuracy..
The way around this is to sample 'current' at the main coil feed which would be a represenitive square wave for all coils one at a time as they fire, just the same as the old single coil system.
An adapter would need to be installed so the voltage drop from the sampling does not get excessive causing misfires during EGR operation.
The factory Tach signal comes from the PCM and is a different wave shape and frequency vs RPM for the digital Tach making an aftermarket Tach useless for accuracy.
Good luck.
.
Problem is today's engines use multiple coils or coil packs.
Sampling from one pack would be at the wrong frequency for Tach accuracy..
The way around this is to sample 'current' at the main coil feed which would be a represenitive square wave for all coils one at a time as they fire, just the same as the old single coil system.
An adapter would need to be installed so the voltage drop from the sampling does not get excessive causing misfires during EGR operation.
The factory Tach signal comes from the PCM and is a different wave shape and frequency vs RPM for the digital Tach making an aftermarket Tach useless for accuracy.
Good luck.
Last edited by Bluegrass 7; Mar 19, 2014 at 12:56 PM. Reason: p
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
I didn't think that the 1997 Lincoln Town Car 4.6L had the dual overhead cams. You sure its not a single overhead cam?
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Those years have a different version of ignition than the 97 up trucks.
I most resembles the V6 system.
This is the progression of ignition systems to todays individual coil over plug system now in use.
The PCM and harness needs to be used but the same issue is still present for Tach use.
Good luck.
I most resembles the V6 system.
This is the progression of ignition systems to todays individual coil over plug system now in use.
The PCM and harness needs to be used but the same issue is still present for Tach use.
Good luck.
Thread Starter
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New User
Joined: Mar 2014
Posts: 4
Likes: 0
Thanks Bluegrass, I think he found a kit from someone that will pick up a signal usable for the tack. 39PU
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