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87 4x4
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89 Posts
Discussion Starter #1 (Edited)
I keep getting a 42 and I have tried everything in the book, had the ignition module tested, check for a short in the wires to the dist. I put it in od and it just bogs down. Have check the timing, when the brown wire unplugged it is at 8 btdc when you plug the wire back in it goes to like 28 to 30. any help, please. Stan
 

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Registered
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10,898 Posts
Set it back to 2* btdc, unhook the battery for a couple minutes
and then reconnect. Take it for a drive..It may be the EST on the
firewall is getting some bad signals from the knock sensor which
results in false retarded timing..Remember almost ANY clanking
on or around the engine can and will be caught by the knock sensor
which "thinks" the engine is detonating and will retard closed
loop timing..In could be this or the circut for the EST is open
or shorted..Hooking up a scan tool in data stream mode and watching
timing as it goes into closed loop will help a lot. Going for
a drive while watching the data stream will help you even more..

The EST circut is responsible for a lot of the timing advance and
retard when in closed loop..If it's messing up = bog and bad
performance..
 

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Long Bed Member
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3,065 Posts
i had the same problem for months and i couldnt figure out what was causing it, no matter if i cleared the codes unhooked the battery whatever it came back. finally i purchased a slightly used EST box off ebay and installed it and ive had no problems or codes since. i dont know why they go bad but it seems like many of them do.
 
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