YJ tach swap question - JeepForum.com
 
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post #1 of 5 Old 04-16-2013, 09:51 PM Thread Starter
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I am finishing a few little things on my 5.3 vortec swap in my 1993 YJ.

It originally had a 4.0, I want to keep the stock guages. I had my ECU programmed to put out a 6cyl signal. I hooked it up tonight and the tach is reading about 200-300 rpm high at idle and gets further out as the rpms increase.

My question is what signal does the stock tach use? is it 6cyl? 4cyl?

I can have my ECU reprogrammed to output what ever signal I need. At least that is what they tell me.

Thanks for any help.

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post #2 of 5 Old 04-17-2013, 07:42 AM
scott66s
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I can't really answer your question but here's some info that might help.


I swapped a 5.3 into a 4cyl 95 jeep. I didn't have the PCM reprogrammed since I am eventually going with aftermarket gauges. So the PCM is outputting what I believe is a 4 cyl signal. My tach reads just about double what the gm PCM is seeing. That would imply that the jeep tach expects to see a 2 cyl signal. But that doesn't really mesh with what your seeing.

Did you check novaks site? I thought there was something on there about the jeep tach.
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post #3 of 5 Old 04-17-2013, 08:57 AM Thread Starter
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Mine is only out a few hundred RPM's so I believe that I can adjust to, at least according to this I can:

http://www.greatlakes4x4.com/showthread.php?t=12025

I would need to change out the resistor since my ECU is putting out a 6cyl signal.
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post #4 of 5 Old 04-17-2013, 10:50 AM
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That's awesome. I am going to do that to mine in the short term. I've already got a stash of resistors laying around to try it out. Thanks.

If your only out a couple hundred rpm's I don't think you're going to need to swap resistors. The pot should be able to make that difference up.
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post #5 of 5 Old 04-17-2013, 10:59 AM Thread Starter
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Quote:
Originally Posted by scott66s
If your only out a couple hundred rpm's I don't think you're going to need to swap resistors. The pot should be able to make that difference up.
This was my thinking as well.
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