Ls1 tach reading not accurate
#2
Launching!
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There is two ways to correct the tach reading incorrect. The signal coming out of the PCM is a 4 cylinder signal and the tach in your dash is a 8 cylinder.
1. Use a tuner program to change the tach signal to 8 cylinder (I would call this the prefered method since it is a computer just change the value.)
2. You can purchase an adapter box that you can set switches to get the correct 8 cylinder signal to the tach. It connects inline between the PCM and tach. The adapter box is on this forum somewhere and I know John B. used one.
1. Use a tuner program to change the tach signal to 8 cylinder (I would call this the prefered method since it is a computer just change the value.)
2. You can purchase an adapter box that you can set switches to get the correct 8 cylinder signal to the tach. It connects inline between the PCM and tach. The adapter box is on this forum somewhere and I know John B. used one.
#4
Launching!
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Originally Posted by mexricanboy26
Thank u.. you say the pcm reading is a 4cl...but the pcm it uses is for ls1 5.7l v8..so it should already have the programming for the v8??
I am in the same position and I have to change my tach to read correctly, but first I need to finish my swap and get it running. Maybe this weekend.