SoCalManche Posted January 17, 2019 Share Posted January 17, 2019 Hey there folks, After much research that has been like pulling teeth, I decided to finally create a Comanche Club account and just ask this myself. A lot of info regarding the Comanches I find is either in regards to the 4.0 models or anything besides the 1986 model. This leads me to believe that the 1986 is a Unicorn model? Anytime I pop the hood, a lot of the time whatever is referenced that I'm trying to swap/mod/upgrade/etc. is not the same for my 'manche. I run a 1986 Renix Comanche 2.5L 4x4. My current issue is figuring out which Coolant Temperature Sensor is correct to use when replacing at the rear driver's side block location. I've seen a few that are identical, and am trying to be pointed in the right direction. Would also love to see if anyone has any threads they could link that deal with the '86 specifically, as the configuration just seems to be a tad different than that of the '87+. Feel free to correct me on anything. I'm just trying to navigate these forums, as well as my truck, in a much more efficient manner. Thanks! Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 The 86 isn't a unicorn, its just weird. I have one out back, but the engine is gone. NTK EF0073 should be what you want. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 1 minute ago, DirtyComanche said: The 86 isn't a unicorn, its just weird. I have one out back, but the engine is gone. NTK EF0073 should be what you want. Unfortunately, this is not the case. The sensor I have is mounted on the rear of the block, and connects via a single, purple wire that can just be popped off. Maybe I'm a fool, and this is the wrong sensor I'm talking about, but if it is wrong, I can NOT find that actual coolant temperature sensor where other's have said it was. Not on the intake, not on the front of the block next to thermostat, nowhere! Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 5 minutes ago, SoCalManche said: Unfortunately, this is not the case. The sensor I have is mounted on the rear of the block, and connects via a single, purple wire that can just be popped off. Maybe I'm a fool, and this is the wrong sensor I'm talking about, but if it is wrong, I can NOT find that actual coolant temperature sensor where other's have said it was. Not on the intake, not on the front of the block next to thermostat, nowhere! It's in the head? For the gauge? Goes in from the top? Not into the block? SMP TS268 or Airtex/Wells 1T1160. But, I think there's a better one that crosses to them, but I'm not totally sure. Either should work. They're under $10. If you really want somebody can look in the actual parts catalog and find a better brand that crosses to that P/N. Link to comment Share on other sites More sharing options...
Pete M Posted January 17, 2019 Share Posted January 17, 2019 a picture might help yeah, 86s aren't unicorns, they are a mix of the old XJs (84-85) and the new tech coming up (like fuel injection). makes them a bit quirky. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 Yeah, they're quirky, not well documented, but most stuff is readily available. I threw out all my 2.5L TBI stuff, apparently it's worth big bucks because some of what is not considered to be 'wear' parts is very hard to get now... So there is that. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 2 minutes ago, DirtyComanche said: It's in the head? For the gauge? Goes in from the top? Not into the block? SMP TS268 or Airtex/Wells 1T1160. But, I think there's a better one that crosses to them, but I'm not totally sure. Either should work. They're under $10. If you really want somebody can look in the actual parts catalog and find a better brand that crosses to that P/N. My bad, I meant to say it's in the head. I can go snag a picture. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 Just now, SoCalManche said: My bad, I meant to say it's in the head. I can go snag a picture. If it's in the head it's for the gauge. Those P/Ns I gave you should work. I believe the later sensors work too, but they may or may not actually cross reference. What is wrong to begin with? Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 13 minutes ago, Pete M said: a picture might help yeah, 86s aren't unicorns, they are a mix of the old XJs (84-85) and the new tech coming up (like fuel injection). makes them a bit quirky. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 8 minutes ago, DirtyComanche said: If it's in the head it's for the gauge. Those P/Ns I gave you should work. I believe the later sensors work too, but they may or may not actually cross reference. What is wrong to begin with? Ha! Do you have about an hour or two to discuss all the issues? Oh...You meant the temp sensor.. Since I received the MJ from the last owner, the temp gauge stays at 100 or so. I'm also running really rich, like REALLY rich, with the MAP and O2 sensors new. Feel free to shed any light. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 Yes, the second batch of P/Ns I gave you are for that. It is for the gauge. Is the gauge always at 100, or is that after it warms up? Either way, the gauge (if it's working) is only telling you what the engine is doing, it is not affecting how it is doing anything. The first batch of P/Ns I gave you are for the sensor that the ECM uses to determine if the engine is hot or cold, and will affect A/F ratio. Personally I don't know much about the TBI units, but they function the same as any other FI system at the end of the day, they will only do as well as they can with the information they're given. You should make sure the CTS for the ECM is functioning correctly, along with the O2 sensor, MAP, and IAT sensors. And of these producing erroneous information can cause a rich condition. Also too high of fuel pressure, or a stuck injector can do this (especially with a TBI). Edit, I'm guessing you're in the US... I assumed 100* C, which is where it should be on the gauge... If as it warms up it gets to 100* F and stops (100* F is only about half of what it should get to), likely the tstat is stuck open and that will also cause a rich condition. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 1 minute ago, DirtyComanche said: Yes, the second batch of P/Ns I gave you are for that. It is for the gauge. Is the gauge always at 100, or is that after it warms up? Either way, the gauge (if it's working) is only telling you what the engine is doing, it is not affecting how it is doing anything. The first batch of P/Ns I gave you are for the sensor that the ECM uses to determine if the engine is hot or cold, and will affect A/F ratio. Personally I don't know much about the TBI units, but they function the same as any other FI system at the end of the day, they will only do as well as they can with the information they're given. You should make sure the CTS for the ECM is functioning correctly, along with the O2 sensor, MAP, and IAT sensors. And of these producing erroneous information can cause a rich condition. Also too high of fuel pressure, or a stuck injector can do this (especially with a TBI). Also replaced the IAT as well. Okay, so are there two different CTS then? Also, it warms up to 100. My Tach is also jacked, as when it shows normal idle is 3,000 - 4,000 rpm, with the needle shooting all the way inverted when I'm in high rev. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 My bad, yes I'm from the States. 100*F, which I know is extremely low. I've thought about replacing the thermostat. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 Just now, SoCalManche said: Also replaced the IAT as well. Okay, so are there two different CTS then? Also, it warms up to 100. My Tach is also jacked, as when it shows normal idle is 3,000 - 4,000 rpm, with the needle shooting all the way inverted when I'm in high rev. Okay, you probably missed my edit. Your gauge is in Fahrenheit? 100 degrees is too low then, and either the sender or gauge is jacked, or the thermostat is bad. Since you have running rich issues, and I'm guessing things are largely unknown with the engine, I would change the thermostat first. There's a CTS that's for the ECM. It's the actual CTS. The one you're talking about is the temp sender for the gauge. No idea on tach issues. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 1 minute ago, SoCalManche said: My bad, yes I'm from the States. 100*F, which I know is extremely low. I've thought about replacing the thermostat. Replace it first. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 The CTS for the ECM is under the intake, in the side of the block. Or so I recall it being, since it's there on the 4.0L and everything is basically the same (minus 2 cylinders). But like I said, replace the tstat first and see what's going on. You could actually just pull the one in there out and see if it closes properly, then test it in a pot of water on the stove (with a thermometer), it should not open until 195* or so. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 2 minutes ago, DirtyComanche said: The CTS for the ECM is under the intake, in the side of the block. Or so I recall it being, since it's there on the 4.0L and everything is basically the same (minus 2 cylinders). But like I said, replace the tstat first and see what's going on. You could actually just pull the one in there out and see if it closes properly, then test it in a pot of water on the stove (with a thermometer), it should not open until 195* or so. That's a neat little trick that I'll definitely try tomorrow. As for the actual CTS, I don't recall seeing it under there, but I can check tomorrow with some daylight. You say everything is basically the same, but I find that to be false, at least in this MJ. Haha! Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 1 minute ago, SoCalManche said: That's a neat little trick that I'll definitely try tomorrow. As for the actual CTS, I don't recall seeing it under there, but I can check tomorrow with some daylight. You say everything is basically the same, but I find that to be false, at least in this MJ. Haha! The 2.5L is just a 4.0L with 2 cylinders removed. Or more or less. That said, I was wrong, they put the CTS in the water jacket in the intake manifold on the TBI 2.5L engines. It's brass coloured, two wires, weatherpack style connector on the pigtail. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 7 minutes ago, DirtyComanche said: The 2.5L is just a 4.0L with 2 cylinders removed. Or more or less. That said, I was wrong, they put the CTS in the water jacket in the intake manifold on the TBI 2.5L engines. It's brass coloured, two wires, weatherpack style connector on the pigtail. I don't have an place to put a sensor there. Even if I did, I don't have an empty green plug anywhere? Again, I'll have to double check on the morning. Link to comment Share on other sites More sharing options...
DirtyComanche Posted January 17, 2019 Share Posted January 17, 2019 That's the thermostat housing. The intake manifold is the thing the TBI is bolted on above the exhaust manifold/header. Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 1 minute ago, DirtyComanche said: That's the thermostat housing. The intake manifold is the thing the TBI is bolted on above the exhaust manifold/header. Yes, I'm aware. I misunderstood your terminology. I read water jacket and auto-deferred to water pump/ thermo-housing. I forgot you said intake manifold water jacket. Yeah, I'll have to look tomorrow, but if I remember, I only recall the IAT being connected to the intake. Link to comment Share on other sites More sharing options...
Eagle Posted January 17, 2019 Share Posted January 17, 2019 7 hours ago, SoCalManche said: Ha! Do you have about an hour or two to discuss all the issues? Oh...You meant the temp sensor.. Since I received the MJ from the last owner, the temp gauge stays at 100 or so. I'm also running really rich, like REALLY rich, with the MAP and O2 sensors new. Feel free to shed any light. The temp sensor in the head ONLY provides a signal to the temp gauge (or idiot light) on the dashboard. If you have a gauge, it's a variable resistance sensor. If you have idiot lights, it's a simple ON-OFF switch. The temp sensor that controls when the ECU switches from open loop to closed loop mode is the sensor on the lower, driver's side of the block. Have you checked or replaced the thermostat? In fact, does it even have a thermostat? Many people don't understand that the purpose of the thermostat is to keep the temperature UP. If someone put in too cold of a thermostat, the engine may never warm up enough to switch into closed loop mode. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 17, 2019 Share Posted January 17, 2019 Temp SENDER is on the head and is for the dash gauge. Temp SENSOR is in the cooling system for the engine computer. If you can hold your hand on the upper radiator hose with the engine at operating temp for longer than 5 seconds, the engine is not reaching operating temp. Check to see if your intake manifold bolts are loosened up. Check the integrity of the vacuum tube from the intake to the MAP sensor. Refresh the braided cable ground at the firewall. This includes removing, cleaning, scraping til shiny!! Have a peek at the vacuum hoses under the throttle body. VERY prone to failure. Clean the c101 connector. And, the 86 is not a unicorn. The same fuel injection system was used on the 4 cylinders for years after 1986 Almost every critical signal between the engine sensors, injectors, ECU, and some to the TCU, travel this path through the C101 connector. That said, the cleaning described below is a real MUST DO right off the bat for any new-to-you Jeep. But, I strongly advocate eliminating the C101 at some point by following the procedure with photos and video in Tip 27. Soldering skills are required and it takes about an hour and a half. The C101 connector is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the ¼” bolt and pull the halves apart. You will find the connector is packed with a black tar-like substance which has hardened over time. Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth. If you have a small pick or dental tool, tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter before bolting both halves back together. If you wish to eliminate this connector entirely (highly recommended), see Tip #27 – C101 Elimination Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 I've got a lot to look at today, so thanks for the info! Cruiser, I've checked out the tips before. My C101 connector is in a more difficult spot to get to. It sits low on the firewall almost in the corner of the driver side fender,hidjg under a bunch of stuff. Any recommendations? Link to comment Share on other sites More sharing options...
SoCalManche Posted January 17, 2019 Author Share Posted January 17, 2019 Oh, and one more question! Does anyone know what size terminal eyelet will fit around the dip stick stud/bolt? I have to cut and replace. Thanks! Link to comment Share on other sites More sharing options...
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