First let me say I know what all these codes are I'm just curious if anyone has a better idea than me on where to start. Here are the codes with rough summarization of what they are. Also heres some background on the jeep as well its a 2001 XJ 4.0 106,XXX miles. Recently(last 2 months) replaced head gasket, replaced Crankshaft Sensor in the last 5 months. Current symptoms rough idle, random jerking/hiccuping when driving(random no particular speed/rpm is the cause), blackened tailpipe.

Anywho onto the codes:
P0151- Heated o2 sensor bank 2 sensor 1
P0201- Fuel Injector Circuit Condition Injector 1
P0202- Fuel Injector Circuit Condition Injector 2
P0300- Random cylinder misfire
P0303- Misfire cylinder 3
P0304- Misfire cylinder 4
P0306- Misfire cylinder 6

Aside from checking all the connections regarding injectors, and coil pack since the head has been off. Anyone have any other ideas as where to start?

Thanks in advance

 

Did you have any codes BEFORE the head gasket replacement?

 

Replace the o2 Sensors, probably needs injectors too

 

Yea random misfire, and I want to say misfire on cylinder 1

 

Well this morning I was driving to work and it threw 3 more codes

P0204- Fuel Injector Circuit Condition Injector 4
P0205- Fuel Injector Circuit Condition Injector 5
P0705- Tranny Range NSS

I haven't yet really had a chance to work on the Jeep b/c unfortunately last paycheck I screwed up my budget and am now paying for my oversight. I find it hard to believe that I've now got 4 "bad" injectors. I dunno. One other question though that I forgot about when I originally posted my thread is that, would any of this cause my cruise to intermittently work? I can set it and it will work just fine and then it will drop for lack of other words "uncruise" almost as if I had hit the brakes or disengaged the cruise control.

 

You also might want to check your fuel injector connections and the wires in the harness. When the head was removed for the head gasket replacement, the wires and or connectors may have been damaged due to carelessness.

 

Wow that's a ton of codes. How's your engine grounds?

 

You very possibly have multiple things going on here. We do need to know WHEN these codes began popping. A long time ago, after the head replacement, etc. The devil is in the details when it comes to troubleshooting.

1. I would start with verifying good engine grounds. Gremlins love bad grounds.

2. The P0300 random misfire and the other misfires are most likely related. Start by verifying fuel pressure. Must be done with a gauge; you should have 49 psi, plus or minus 5 psi.

3. Inside of the power distribution center (black box under the hood on the passenger side), check the mini 15 amp fuse that controls oxygen sensor heater operation. It is not that unusual to find it blown. Anytime you have a code that has the word "heater" in the description, you should check this fuse! Not exactly sure of the location, somewhere around slot 17 or 19 I think. If it is not blown and the oxygen sensors have over 100k on them, I'd certainly consider replacing them with new NTK sensors.

 

This could be a clue. Do you have a digital voltmeter and are familiar with the throttle position sensor (TPS) on the throttle body? If so, I think it would be a good idea to check the PCM sensor reference voltage at the TPS. The reference voltage should be 5 volts (+/-) with the ignition key in the RUN position (but engine not started).

Remove the TPS connector and place the (+) probe of the meter on the right pin socket (right=as you are looking at the disconnected connector - Orange wire) and the (-) probe of the meter on the left pin socket (Brown wire/Yellow tracer). You should see 5 volts DC. If not, probe to the right pin socket and the (-) probe to the battery negative terminal, again, it should be 5 volts DC.

If the reference voltage is high, like near 12 volts, the clocksping may be defective, bleeding battery voltage from the horn relay control coil through the cruise control circuit to the PCM. If this is happening you can remove the horn relay in the Junction Block (passenger footwell) and see if it stops. You can leave the horn relay out until you can change the clockspring. As long as you have a middle finger you really don't need a horn anyway.

Give it a try (voltage reading) and let us know what you find.

PS: If you need to know where the horn relay is in the JB, I can show you. I take Paypal...

 

all right guys so I have a four day weekend for mlk so I've finally got some down time to look at the jeep. Thus far the ground from the firewall to the block is tight, dusty but no corrosion. All the fuses in the fuse block under the hood are good. The voltage on the TPS connector with the key in on run is -108.9 lol I did probe both the connector and the battery to the connector

 

WTF?

Explain.

 

This

edit* I probed connector first and then did the above.
double checked for whatever reason the multimeter im using is giving me a mV reading.

 

Select 20 VDC on your meter.

 

I dont have 20vdc on the multimeter it switches from I can tell automatically. I did my battery and it read -12.28 vdc when I do what you told me it for whatever reason is giving mV. The only options I have are VDC and VAC

 

Get another digital volt/ohmeter that you can select the various ranges you need. They're cheap at Harbor Freight and other stores.

I have one of those auto select meters. It's okay for certain aps, but I use my $30 meter for troubleshooting.

No sense going any further unless you can positively know what voltage you want to be reading, not what some dime store meter says what it wants you to read.