Bad Idle rough take off. Bad o2 Harness? - JeepForum.com

 
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post #1 of 8 Old 02-26-2007, 06:41 PM Thread Starter
SAZJ
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Bad Idle rough take off. Bad o2 Harness?

Ok so I was having a problem with my o2 sensors. Its reading a hot o2 sensor even when the engine is turned off. leads to either an ECU problem or a Wiring harness. Anyways I have had this problem for about 4 months, and it was running fine. But I disconnected the battery and then it was no longer reading the code, until I did a full throttle acceleration at which point the o2 warning came back on. Also when i disco the battery and then reconnected it the jeep started idling really rough when in gear, and then any tap on the gas at all and it will jump really hard and then sputter. Any Ideas on what I should check out? its got 2 new o2 sensors so I know thats not the problem.

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post #2 of 8 Old 02-26-2007, 07:03 PM
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Check the wires coming from the harness to see if they're nicked. The ECU is not real-time, so it'll store your hot O2 sensor code. I would suspect you could see the issue pretty close to the sensor if the harness is messed up.

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post #3 of 8 Old 02-26-2007, 07:07 PM
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You need to explain the issue better. What does it mean that the sensor reads hot? Do you mean that the heating element in it is on when the engine is off? What codes were thrown? What engine do you have? Is it only for the upstream 2 sensors?

Cheers Steve

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post #4 of 8 Old 02-26-2007, 07:13 PM Thread Starter
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The guy who pulled the code said it was sensor 1 bank 1, that it was "Hot" even when the engine was off, I assume he means that the sensor is in error. But he did say I should be extremely worried about it, so maybe he ment that it actually was temp. hot. Its a 5.2l I believe that its code on the machine was something like p2039 But he didn't let me look at it
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post #5 of 8 Old 02-26-2007, 07:30 PM
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I'm pretty sure he's refering to a cylinder. If Steve pops in again , he may be able to tell you which side is bank one and which cylinder is #1. Check the coil. I had a bank 1 #2. The coil was cracked so the cylinder would'nt fire. The computer then cut off fuel to the cylinder making the engine seem to run smooth again but lacking a bit of power. Anyway, the code came up with a lean #2 cylinder. This is a newer Winstar limited but same idea, Just a little more software. Like cutting off the fuel to the cylinder to stop the cat. from melting down.

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Last edited by rxl; 02-26-2007 at 07:45 PM.
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post #6 of 8 Old 02-26-2007, 08:00 PM Thread Starter
SAZJ
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Its bank 1 Sensor 1 He is referring to the first o2 sensor not cylinder. But I do appreciate your input. All 8 Cylinders are firing correctly, its just idling a little rough like its running lean. The code was improper voltage o2 sensor Bank 1 Sensor 1
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post #7 of 8 Old 02-26-2007, 08:14 PM
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Thatís the driverís side upstream sensor. I still donít get what is meant by hot. Temperature hot or that it has juice. I assume that it is temperature hot Ö but of course it will be for awhile so that really doe not make much sense either

Cheers Steve

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88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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post #8 of 8 Old 02-26-2007, 08:16 PM
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Yep that means the sensor is NFG. Only use Mopar sensors. Most aftermarket ones do not work well (especially Bosch)

Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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