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Unread 01-07-2012, 02:36 PM   #31
Bad_Dog
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The temp sensor registered between .860 and .998 ohms. That is, if I'm reading my meter correctly. Either I'm not or the sensor is off a tad.

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Unread 01-07-2012, 03:12 PM   #32
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Quote:
Originally Posted by Bad_Dog View Post
The temp sensor registered between .860 and .998 ohms. That is, if I'm reading my meter correctly. Either I'm not or the sensor is off a tad.
185.00 ohms VS .998 ohms is more than a tad!!
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Unread 01-07-2012, 03:18 PM   #33
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Quote:
Originally Posted by Bad_Dog View Post
What if I run the Jeep at normal temp (190F?) and then take a reading on the sensor? I'll see if it's around 185 ohms.

But so far, everything sounds like it's a bad O2 sensor. Are the voltage readings that I'm getting, are they a good indicator that it's not good?
That would be a good idea to take the readings at the normal temps. Also it should be running when you read the O2 sensor too. BUT so far looks to be way out of whack - O2 sensors in general its not just for jeeps should show bout 0.5 volt thereabouts when running.
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Unread 01-07-2012, 03:30 PM   #34
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185.00 ohms VS .998 ohms is more than a tad!!
I just think back to Airplane: The Sequel:

Passenger: "Stewardess, what exactly is a 'tad'?"
Elaine: "In space terms, that's half a million miles."

I read up some more on O2 sensors. 0.1~0.3 if it's running lean, .8~.9 if it's running rich, and 0.45 if it's "just right". Since my readings were giving me between .8 and .9 volts, that tells me that the 'rich' reading is being read correctly by the O2 sensor. I'm fairly certain the O2 sensor is okay.

Having said that, since my temp sensor is giving me a @$!% reading, it sounds like I have my culprit. Sucks that my O2 and my temp sensor went out roughly at the same time.

Since I can't find my Haynes manual, is swapping out the temp sensor an easy thing? Looks to me you just unscrew it and put the new one on. Any sealant need to be put on the threads upon installing the new one?

BTW, thanks to everyone's help!!! I was working on this while I was also repairing a leaky window in my home office and taking down the Christmas decorations.
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Unread 01-07-2012, 03:55 PM   #35
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Originally Posted by Bad_Dog View Post
I just think back to Airplane: The Sequel:

Passenger: "Stewardess, what exactly is a 'tad'?"
Elaine: "In space terms, that's half a million miles."

I read up some more on O2 sensors. 0.1~0.3 if it's running lean, .8~.9 if it's running rich, and 0.45 if it's "just right". Since my readings were giving me between .8 and .9 volts, that tells me that the 'rich' reading is being read correctly by the O2 sensor. I'm fairly certain the O2 sensor is okay.

Having said that, since my temp sensor is giving me a @$!% reading, it sounds like I have my culprit. Sucks that my O2 and my temp sensor went out roughly at the same time.

Since I can't find my Haynes manual, is swapping out the temp sensor an easy thing? Looks to me you just unscrew it and put the new one on. Any sealant need to be put on the threads upon installing the new one?

BTW, thanks to everyone's help!!! I was working on this while I was also repairing a leaky window in my home office and taking down the Christmas decorations.
Temp sender is easy, just like a spark plug: unscrew old, screw in new and put wire back on. Do NOT put anything on the threads because that is what it grounds thru. You want the sender that's on the water neck (thermostat housing).

About the O2 sensor see, yours was reading rich even tho the plugs don't look rich at all. Same deal with the O2 sensor, just unscrew old, screw in new and plug wires back on.

BUT like I said, if your temp sender is reading low, then the computer isn't even going to read the O2 sender.
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Unread 01-08-2012, 01:14 PM   #36
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I replaced the temp sensor with a new one, reset the computer, and the problem hasn't gone away. The computer is still giving me code 52. I put my meter on the new sensor and it's giving me the same reading. Maybe I'm not using my digital multimeter correctly; it's old and I no longer have the manual. That, or I just purchased a bad one, which I'm doubting since I now have two sensors giving me the exact reading. (sigh)
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Unread 01-08-2012, 05:30 PM   #37
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Quote:
Originally Posted by Bad_Dog View Post
I replaced the temp sensor with a new one, reset the computer, and the problem hasn't gone away. The computer is still giving me code 52. I put my meter on the new sensor and it's giving me the same reading. Maybe I'm not using my digital multimeter correctly; it's old and I no longer have the manual. That, or I just purchased a bad one, which I'm doubting since I now have two sensors giving me the exact reading. (sigh)
How does it run?

To re-set the brain did you remove the + battery cable from the battery and ground that cable end for for 30 seconds or more then re-attach the battery cable?

Just checking...
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Unread 01-08-2012, 05:58 PM   #38
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What mystifies me is that your plugs look fine but it still runs poorly - and they don't look rich at all despite the code reading. Furthermore the trouble only happens when its in open loop, not when its warmed up. I'm pretty sure your meter reading is OK.
I'm starting to think the trouble is elsewhere, but frankly my brain is too tired out tonight - I would ask Que89YJ in the morning.
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Unread 01-08-2012, 06:20 PM   #39
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Just had an idea tho - are the intake/exhaust manifold bolts all tight where it bolts onto the head?
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Unread 01-08-2012, 07:48 PM   #40
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How does it run?

To re-set the brain did you remove the + battery cable from the battery and ground that cable end for for 30 seconds or more then re-attach the battery cable?

Just checking...
After installing the temp sensor, and resetting the PCM, I started it up. It seemed to be okay at first, but after a few moments, I noticed that it began idling rough, like it normally does.

To reset it, I disconnect the negative terminal for at least one minute. I then check the diag again to confirm that it only shows 12.

Today after I installed the new sensor and reset it, I started it up and it idled fine. I drove it for a few miles and got it up to 190F, pulled over, parked it and shut it off for 30 seconds. Started it up - started up fine, no hesitation (which it doesn't normally do after its warmed up) and drove for a few more miles. Pulled into a parking lot, parked it, shut it off for 30 seconds. Started it up and drove back to my house. In all, about five miles; up and down hills, around sharp bends, etc. Got home, shut it off and run the diag. Got 12, 52, 55.

Driving it around, it drove fine, which is why I'm surprised that it threw a 52 after I got home; I wasn't expecting it.
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Last edited by Bad_Dog; 01-08-2012 at 08:08 PM.. Reason: re-worded first paragraph
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Unread 01-08-2012, 08:01 PM   #41
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What mystifies me is that your plugs look fine but it still runs poorly - and they don't look rich at all despite the code reading. Furthermore the trouble only happens when its in open loop, not when its warmed up. I'm pretty sure your meter reading is OK.
I'm starting to think the trouble is elsewhere, but frankly my brain is too tired out tonight - I would ask Que89YJ in the morning.
.
If it helps, I put a can of Seafoam into a full tank of gas, once, every summer, ever since I replaced the plugs a few years ago. I don't put much mileage on it, less than 3k a year.

Outside of how it idles when it's cold, when you first start it up, you'd never know there was a problem. It drives fine once it's warm.
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Unread 01-08-2012, 08:04 PM   #42
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Just had an idea tho - are the intake/exhaust manifold bolts all tight where it bolts onto the head?
.
I might be able to check again next weekend. I can't work on it during the week because I get home after it's dark and I have an 11 month old son that goes to sleep around 8:30. By the time I get him to bed, I'm exhausted from the day. And since I don't have a heated garage, I only work on it in the driveway during the day.
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Unread 01-08-2012, 08:14 PM   #43
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Personnaly I believe your issue is with the O2 sensor, either the sensor itself or the wiring, since the issue started after you had it changed and your plugs obviously don't show rich mixture, unless you need to run a bit longer maybe to actually get them carboned. If it was running rich, you'd be able to see it (black smoke coming from the exhaust) or at least smell it (strong fresh fuel smell from the exhasut). Here's a couple of free things you can try : Take a look at your cat converter, make sure it's not clogged or wack it a few times and listen for some rattling, make sure you dont have ANY vacuum leak (lines, gaskets, and what not) and lastly test the MAP sensor since it's the one that controls mixture :



Inspect the MAP sensor vacuum hose connection at the throttle body and sensor, then repair as necessary.

Test the MAP sensor output voltage at the sensor connector terminal B (as marked on the sensor body) with the ignition switch ON and the engine OFF. The output voltage should be 4–-5 volts.
NOTE: The voltage should drop to 0.5–/1.5 volts with a hot, neutral idle speed condition.

Test engine controller terminal 5 for the same voltage as in Step 2 to verify the wire harness condition. Repair any problems, as necessary.

Test the MAP sensor supply voltage at the sensor connector terminal C with the ignition ON. The voltage should be 4.5–/5.5 volts. The same voltage should be present at terminal 6 of the engine controller wire harness connector.

Repair or replace the wire harness, as necessary. If the engine controller is suspect, use Diagnostic Tester M.S.1700, or equivalent, to test engine controller function.

Test the MAP sensor ground circuit at the sensor connector terminal A and engine controller connector terminal 4. Repair the wire harness as necessary.

Test the MAP sensor ground circuit at the engine controller connector between terminal 4 and terminal 11 with an ohmmeter. If the ohmmeter indicates an open circuit, check for a defective sensor ground connection located on the right side of the cylinder block. If the ground connection is good, replace the engine controller.
NOTE: If terminal 4 has a short circuit to 12 volts, correct this condition before replacing the engine controller.
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Unread 01-08-2012, 08:31 PM   #44
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Personnaly I believe your issue is with the O2 sensor, either the sensor itself or the wiring, since the issue started after you had it changed and your plugs obviously don't show rich mixture, unless you need to run a bit longer maybe to actually get them carboned. If it was running rich, you'd be able to see it (black smoke coming from the exhaust) or at least smell it (strong fresh fuel smell from the exhasut). Here's a couple of free things you can try : Take a look at your cat converter, make sure it's not clogged or wack it a few times and listen for some rattling
I don't get black smoke, but white'ish smoke. I do get a fair amount of condensation spitting out the exhaust. Today, I noticed that where the cat meets the muffler, that coupling had some moisture dripping from it while it was running.

I didn't notice it today (I may have simply ignored it because I'm used to it), but since I've had this problem, there is a strong gas smell from the exhaust.

It's hard to tell if the cat is truly rattling. The outer shielding (heat shield?) came off a few months ago. The top part I was able to remove, but the bottom part is still hanging out, in between the cat and the skid plate. Since I can't get to it without removing the skid plate, I've left it there.
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Unread 01-08-2012, 08:49 PM   #45
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With a stone cold engine. Unplug the O2 sensor and see how it starts/runs. If it does run OK shut it off then do the same thing again with the O2 sensor pluged back in and see if it starts crappy. If it does then it is O2 sensor related I would think.
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