Trailing coil not firing?
#1
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
Trailing coil not firing?
I have a 87 N/A and it seems that the trailing coils only fires about 20% of the time. Ive checked the main relay and the coil itself are fine. Ive also noticed that when the tach works the coil fires too. My next step is to check the ECU to see if its sending the input signal to the coil. Any other suggestions?
#2
Retired Moderator, RIP
iTrader: (142)
Join Date: Sep 2005
Location: Smiths Falls.(near Ottawa!.Mapquest IT!)
Posts: 25,581
Likes: 0
Received 131 Likes
on
114 Posts
check your plugs.
The Tach will read RPM off the coil by the spark it supplies to the plugs.
If the spark is not there the tach just doesn't read.
If you get spark between the wire and the coil But get no Tach,then your plugs are most likely fouled.
Also it is a good idea to remove the trailing coil and clean up any grounds in that area.Scrape the body and contact points down to metal so it will get a good solid ground contact.
The Tach will read RPM off the coil by the spark it supplies to the plugs.
If the spark is not there the tach just doesn't read.
If you get spark between the wire and the coil But get no Tach,then your plugs are most likely fouled.
Also it is a good idea to remove the trailing coil and clean up any grounds in that area.Scrape the body and contact points down to metal so it will get a good solid ground contact.
#3
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
check your plugs. The Tach will read RPM off the coil by the spark it supplies to the plugs. If the spark is not there the tach just doesn't read. If you get spark between the wire and the coil But get no Tach,then your plugs are most likely fouled. Also it is a good idea to remove the trailing coil and clean up any grounds in that area.Scrape the body and contact points down to metal so it will get a good solid ground contact.
#4
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
Let me clarify, the spark test was only sucessful 2/6 times. It will always show spark for the first two second of cranking the motor but once the motor is running spark will totally cut out and my tach will stop working. Thats what happens of the test that fail to provide spark
#5
Moderator
iTrader: (1)
What is the voltage output of the B+ wire from the alternator while idling. Too low of a reading and it could cause the trailing coil to stop working properly. Also, did you unbolt and clean the mating surfaces between the coil and fender as this is how the coil/igniter grounds.
#6
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
What is the voltage output of the B+ wire from the alternator while idling. Too low of a reading and it could cause the trailing coil to stop working properly. Also, did you unbolt and clean the mating surfaces between the coil and fender as this is how the coil/igniter grounds.
Trending Topics
#8
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
#9
Moderator
iTrader: (1)
3 ECU pins associated w/the trailing coil are as follows. 1X (Blue/Yellow) reads 0 volts w/key to on and .8 volts while idling. 1U (Brown/Yellow) reads 4.4 volts w/key to on and 2.2 volts while idling. 1M (Blue/Red) reads below 2 volts w/key to on and while idling (mine reads 1/3 volts at idle).
#10
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
3 ECU pins associated w/the trailing coil are as follows. 1X (Blue/Yellow) reads 0 volts w/key to on and .8 volts while idling. 1U (Brown/Yellow) reads 4.4 volts w/key to on and 2.2 volts while idling. 1M (Blue/Red) reads below 2 volts w/key to on and while idling (mine reads 1/3 volts at idle).
#12
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
#15
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
#16
Moderator
iTrader: (1)
Why? If the lead coil is fine then the ignition switch has nothing to do with it. Did you ever get around to the arduous task of unbolting the trailing coil and cleaning the mating surfaces and bolt threads? The wire you get 12 volts on will occur if the coil/igniter is not grounded properly. If grounding the coil does not fix things then the coil probably needs to be replaced.
#17
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
Why? If the lead coil is fine then the ignition switch has nothing to do with it. Did you ever get around to the arduous task of unbolting the trailing coil and cleaning the mating surfaces and bolt threads? The wire you get 12 volts on will occur if the coil/igniter is not grounded properly. If grounding the coil does not fix things then the coil probably needs to be replaced.
#19
Full Member
Thread Starter
Join Date: Feb 2014
Location: Ewing, NJ
Posts: 101
Likes: 0
Received 0 Likes
on
0 Posts
#20
Moderator
iTrader: (1)
When you switched the ECU did you test the troubled Blue/Red wire? If it is still the same then the problem is either the coil or the connection to the coil (and or possibly the ECU). Make sure the wire is not pulled back within the plug and thus not mating w/the coil/ECU.
Thread
Thread Starter
Forum
Replies
Last Post
windom
Adaptronic Engine Mgmt - AUS
4
09-11-15 04:48 AM