governor culprit...maybe? - JeepForum.com

 
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post #1 of 9 Old 08-27-2015, 05:02 PM Thread Starter
munin
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governor culprit...maybe?

So I traded the xj and the yj in for another tj. Anyways I'll cut through the bs and get to the point. Currently on 33's with 4.56 gears 2004 wrangler sport. Issues: speedometer was 25mph to 30mph off the other day. At around 60-65mph+ via gps (90-95mph speedometer) felt like the jeep hit top speed and the governor said "holy crap" and cut out until I dropped below 90ish on the speedometer. Drove home and kept the speedo at 80-85 (60ish via gps) no issues. Today the speedometer was off by about 50mph. So at 45 to 55mph (95-100mph speedometer) it did it again. It only happens when the speedometer hits 95ish and cuts out the acceleration and drops speed then completely normal. Actual speed doesn't matter because it's only when the speedometer hits 95ish. Is there a sensor that is connected to the speedo gear plug or something that maybe tells the computer that I'm doing this speed when I'm actually not?

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post #2 of 9 Old 08-27-2015, 05:11 PM
freeskier93
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The speed on the speedometer is the speed the computer thinks you are going. There is a speed limiter around 100, I had the same issue with my gear/tire combo and it kicked in when the computer thought I was going around 105 (needle was actually past marked speeds) but was really going about 75. The solution is to install the correct speedo gear for you gear/tire combo to correct the speedometer. However, if the speedometer error is changing for any given speed you have another issue going on. Any error is going to be a fixed percent and shouldn't be changing day to day.
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post #3 of 9 Old 08-27-2015, 05:11 PM
JBTJ
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You need to replace the $40 speedometer gear in the transfer case. Takes maybe 5 minutes to do. Here is how and where I bought mine.

http://www.4x4xplor.com/speedo.html

http://www.transmissioncenter.org/sp...e_and_jeep.htm
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post #4 of 9 Old 08-27-2015, 05:11 PM
biffgnar
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There is a limiter on TJs. Fix your speedo.

#feelthejohnson
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post #5 of 9 Old 08-27-2015, 05:21 PM Thread Starter
munin
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I ordered one last night for 40 bucks. 90 teeth just to fix the speedometer reading driving me nuts. Would unplugging it till then stop it from happening till I get the right one? Seems like it would make sense right? Seems like the speedo gear is slipping and adding more fake mph. Just worried next time I'll be stuck doing 40 on the hwy or worse. I'll have to open it up tomorrow when I get home to see what's going on till the new one gets here. What do you think?
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post #6 of 9 Old 08-27-2015, 05:26 PM
JBTJ
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Quote:
Originally Posted by munin View Post
I ordered one last night for 40 bucks. 90 teeth just to fix the speedometer reading driving me nuts. Would unplugging it till then stop it from happening till I get the right one? Seems like it would make sense right? Seems like the speedo gear is slipping and adding more fake mph. Just worried next time I'll be stuck doing 40 on the hwy or worse. I'll have to open it up tomorrow when I get home to see what's going on till the new one gets here. What do you think?
Just so you know you need a 39 tooth gear, and that will fix your problem. There is nothing wrong with the speedometer gear that you have now. It's just not the correct one for your tire/gear combination. That's all.
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post #7 of 9 Old 08-27-2015, 05:38 PM Thread Starter
munin
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Quote:
Originally Posted by JBTJ View Post
Just so you know you need a 39 tooth gear, and that will fix your problem. There is nothing wrong with the speedometer gear that you have now. It's just not the correct one for your tire/gear combination. That's all.
Yes thats correct. Not sure why I thought 90. Just wondering because of the big jump from being 25 off to 50mph off. In the beginning it was only 12 off. Seems to be everywhere it wasn't but doesn't help on the hwy. My little 2.5l yj is laughing at me right now. Thanks all.
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post #8 of 9 Old 08-27-2015, 08:24 PM
mrblaine
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Quote:
Originally Posted by munin View Post
Seems like the speedo gear is slipping and adding more fake mph.
Your logic is backwards. If it was slipping, (it isn't) it would be reducing the mph. The only time slipping adds mph without adding ground speed is when the tires don't have traction, mud, snow, ice, etc.

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post #9 of 9 Old 08-27-2015, 10:43 PM
Knuckelhead
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Quote:
Originally Posted by biffgnar View Post
There is a limiter on TJs. Fix your speedo.
When I first got my 2000 Sport it had 33x9.5 BFG's and 3:55 axle gearing (T/C gear was correct for the speedometer).

While learning the limits of its capability I found that the load being applied to the drivetrain differed at what speed the limiter would restrict the speed.

If I was driving on a flat or down hill grade (no wind factor) I could achieve 95 mph and never encountered the limiter.

Coming back from one trip I was encountering 30+ mph head winds and the limiter kicked in between 80 and 85 mph.

As I said, I was testing what it could do. Now it never goes above 60 mph and its doing well... IMO
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