torque062

I would probably try to warranty out that o2 sensor.

kylan1234

I'm using a Bosch o2, everyone says they're junk and to use NTK or oem. Could that factor into it?

CCKen

You may want to test your MAP Sensor.

Open this link and go to post #53. There's a pic of back probing a MAP Sensor.

https://www.cherokeeforum.com/f2/gre...e-6558/index4/

MAP Sensor test:

The MAP sensor input is the number one contributor to fuel injector pulse width (rich/lean).


The PCM uses the MAP sensor input to aid in calculating the following:

• Manifold pressure
• Barometric pressure
• Engine load
• Injector pulse-width
• Spark-advance programs
• Shift-point strategies (certain automatic transmissions only)
• Idle speed
• Decel fuel shutoff

Testing:

Using a digital voltmeter, back probe the MAP sensor connector while it’s attached to the MAP sensor and take the following readings.

Test the MAP sensor output voltage at MAP sensor connector between terminals 1 (Brown/Yellow tracer wire) and 2 (Dark Green/Red tracer wire).

With ignition switch ON and engine OFF, output voltage should be 4-to-5 volts.

With engine running, the voltage should drop to 1.5- to-2.1 volts with a hot, neutral idle speed condition.

~~~~~~

Higher MAP voltage equals higher load/more fuel delivered.

Lower MAP voltage equals lower load/less fuel delivered.

I did notice that your load was 12.9 at hot idle. I normally see around a load of 5 at hot idle.

kylan1234

Actually my load % is around 4.7 until the Jeep starts acting up. I think it may be a faulty o2 sensor because it will bounce from .1 to .7 back and forth and then eventually stay no higher then .2 volts,

kylan1234

Here is some more photos from a Live data report. You can see how normal everything is but as soon as the o2 sensor voltage starts dropping then thats when she acts up.

kylan1234

Here is how much her voltage jumps around on the o2

CCKen

Does the downstream O2S always stay at 1.000? If so, that is not good. The downstream O2S should be cycling just like the upstream.

STFT of -20.3 is no good also. It's pulling alot of fuel off. ECT or IAC may be causing this.

ECT 158*F vs. IAT 114*F is no good. See if you can hook up your scanner in the morning before starting the engine and check the ECT and IAT temps. They should be within 3*F of each other. Based on the outside air temp when you take the reading in the morning will tell you which temp ensor needs to be changed, or investigated.

Did you say "You can see how normal everything is...".

kylan1234

Okay I will do that. My downstream o2 is reads between .8 and 1.1. It just happen to shoot the pic when it read 1.0. What should my o2 sensors voltage be at?

kylan1234

I checked my live data report this morning with engine being off for around 14 or 15 hrs. IAT and ECT both read 69 degrees. Outside temperature is 69 degrees as well.

kylan1234

After doing some research I have found that a lot of Jeeps have problems with Bosch o2 sensors. I tried to warranty it out but they wouldn't do anything but give me a new Bosch which I dont want. I switch to an NTK o2 and the Jeep has ran good all day. Her fuel trims stayed perfect. I don't want to get ahead of myself and this be a "patch" fix but she ran better today then she has in months.

CCKen

It's amazing what parts that belong in an XJ 4.0 can do!

Plugs, OEM Crank sensor, OEM Cam sensor, OEM TPS, etc.

kylan1234

Yeah for real. I just hope this fixes it for good