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Tach not working after engine install????help!

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Old Aug 5, 2009 | 01:33 PM
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Default Tach not working after engine install????help!

Just did a a4 to m6 swap and had the motor out to fix some leaks and install ls2 gto cam that was laying around.

I bought the ls2 cover and extension harness.
Got it fired up and my tach does not work!!!

Where does the computer get the signal for the tach? Crank or cam sensor or both, neither???

Could it be something with the a4 vs m6 program? I haven't gotten it reflashed and tuned yet but will next week.

Is it possible that something is not hooked up correctly on the engine harness? I installed a M6 harness during the swap.

thanks!!
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Old Aug 5, 2009 | 01:40 PM
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Check the cam sensor and wiring. If you're using the Casper's or Katech wiring extension you will likely just need to swap the outer two wires on the harness (A&C) and you'll be good to go. Other symptoms of that issue are a hard start and difficulty idling.
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Old Aug 5, 2009 | 01:51 PM
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I think it is the casper's harness. Why would I have to swap the outer two wires? They hooked up wrong in the extension from casper's?? is this common? Don't have it in front of me (at work now), but how many wires are there? Do I just need to pull the pins on the outer two and swap them? It does seem to have some starting issues as well.

THANKS!!
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Old Aug 5, 2009 | 02:28 PM
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There are three wires (A, B, & C) on the harness. It is fairly common!
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Old Aug 5, 2009 | 02:44 PM
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Originally Posted by Matt@Texas-Speed
There are three wires (A, B, & C) on the harness. It is fairly common!
NICE...... I will have to try that. Funny you mention this because my buddy got two sets of Casper's O2 extensions that were wired wrong!

I will try to compare the engine harness and the prongs to what prong they hook up to on the sensor and verify prior to taking appart.

Thanks for the info, you may have saved me a ton of agrivation....
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Old Aug 6, 2009 | 02:03 PM
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Problem Fixed!!!! Thanks Matt!!

It looked like the extension had the wires flipped from end to end (like what was shown if you extended your existing harness) and the little pig tail that came on the cover also had them flipped. So, flip + flip = back to normal.....

I cut the ones on the extension and switched and soldered them. Couldn't get them out of the plug, so just cut, soldered and shrink wrapped.
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Old Aug 6, 2009 | 02:18 PM
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Glad to help
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