Eagle_SX4 Posted January 26 Share Posted January 26 So I broke the inline speed sensor I installed on my Eagle when I swapped to fuel injection on the '92 4.0 that's in it. I have a new one on order but would like to continue to drive it until the new one comes in the mail. I am curious what the data from the speed sensor is used for. How is that going to affect driveability? I assume the fuel mixture won't change based on load/speed. Would it be more likely to run rich or lean? Link to comment Share on other sites More sharing options...
gogmorgo Posted January 26 Share Posted January 26 I’ve driven my ‘91 with the speed sensor unplugged. The most noticeable effect is just the speedometer/odometer not working. Cruise doesn’t work either. Otherwise there’s no difference in driveability. The AW4 still shifts normally. Speed sensor data is included in the DRL logic if equipped, it wants to see the vehicle rolling, best guess they might not come on with no input but I didn’t ever check. Shift light might also be affected with a manual I guess. I doubt the speed sensor plays much into the engine tuning. Not really a relevant factor to monitoring engine load and air/fuel ratio. It didn’t seem like it was using any more or less fuel although I wasn’t paying a ton of attention. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 26 Share Posted January 26 can we see pics of your Eagle please? Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted January 26 Author Share Posted January 26 Thanks @gogmorgo my speedometer still works since it is cable driven and I just plugged it back into the transfer case after removing the speed sensor. @cruiser54 there are lots of photos on my build page(link in my signature) but here are a few I have wrapped the wire harness since I took this photo and put about 2,500 miles on the fuel injection. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 26 Share Posted January 26 I had a wagon in that color. a Limited. Wish I still had it. I bought it off a customer at the dealership when I was Service Manager. My wife loved it. Swapped it to 3.55 gears from the 2.35 gears it had. Added the factory rear sway bar. De-smogged it. But, it had a weird issue that scared the hell outta my wife. Sometimes, randomly, it would bog when accelerating into traffic. I didn't now then what I found out later. That POS Ford ignition module could cause that issue. The simple solution was to get an HEI distributor from a straight 6 GM motor, swap an AMC v8 gear on to the bottom, give the dizzy a 12 volt ignition source, gap the plugs to .045" and haul @$$. I did that conversion to numerous Jeeps after it became common knowledge. Now you can buy complete dizzys off the internet. FWIW, I have the hand written notes of the AMC engineer outlining the factory parts needed to put an AMC V8 into an Eagle. The only thing needing fabrication is the front diff mount to the engine. Link to comment Share on other sites More sharing options...
schardein Posted January 26 Share Posted January 26 Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted January 26 Author Share Posted January 26 Thanks for the info @schardein. It looks like the speed sensor is used to adjust the automatic idle speed (AIS) motor upon deceleration. It is also used as the input for cruise control, which I don't have. I also remembered I had a PDF of the 91 service manual and here are some screenshots detailing the speed sensor. It looks like it will run and drive fine (with a manual transmission) an automatic might have some deceleration problems with idle speed. Otherwise not affect much. Link to comment Share on other sites More sharing options...
89 MJ Posted January 26 Share Posted January 26 2 hours ago, cruiser54 said: I had a wagon in that color. a Limited. Wish I still had it Not to continue the Eagle talk, but it seems most limiteds had that brown. My 85 parts car was light tan on the top with that brown on the bottom Link to comment Share on other sites More sharing options...
schardein Posted January 26 Share Posted January 26 10 minutes ago, Eagle_SX4 said: Thanks for the info @schardein. It looks like the speed sensor is used to adjust the automatic idle speed (AIS) motor upon deceleration. You're welcome. Yes, I would do a short test drive and expect minimal issues, especially with a manual. If that went well, I wouldn't be afraid to drive it. I have some limited experience tuning LS engines, and that has been my experience with the speed sensor in that application (manual trans) as well, making changes affects how the engine behaves in deceleration. Link to comment Share on other sites More sharing options...
schardein Posted January 26 Share Posted January 26 Forgot to mention, I have a couple spare '91 YJ speed sensors with the speedo cable pass through, if your new one doesn't show up. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted January 26 Author Share Posted January 26 The same speed sensor was also used on the Dodge Dakotas of the early 90's. I got a shipping notification and my new sensor is on its way. Car drives fine. So far driven about 40 miles up to the local ski resort enjoying my early weekend. Link to comment Share on other sites More sharing options...
schardein Posted January 27 Share Posted January 27 5 hours ago, Eagle_SX4 said: The same speed sensor was also used on the Dodge Dakotas of the early 90's. I got a shipping notification and my new sensor is on its way. Car drives fine. So far driven about 40 miles up to the local ski resort enjoying my early weekend. exactly right, I think my spares are actually from Dakotas. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted January 27 Share Posted January 27 If you’re running HO fuel injection, you will eventually start to have it dying when coming to a stop if your vss isn’t sending a signal to the ecu. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted January 27 Author Share Posted January 27 Thanks @ghetdjc320 I won't drive it much until I get the new sensor put on. Link to comment Share on other sites More sharing options...
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