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Discussion Starter #1
Hey Everyone,

New around here (I've lurked, but haven't posted yet...you've all already helped me more than I can express.) Recently purchased a 2007 XK 3.7 with QTi that wouldn't start, I replaced the fuel pump and got her to fire up, but she's not happy.

Good news is I don't hear anything that sounds painful, just sputtering, and vibration. Bad news is I've got the oh-so-helpful P0300 with no other codes. I put in new plugs as the old ones were nice and charred. I'm going to pick up some new coils later today, and see if they sort it out.

The jeep sat for almost 3 months before I got it, and while I didn't add all of the gas that was in the tank back, I did add about 5 gallons after the pump change somewhat absent-mindedly. I've since added a bottle of HEET and 5 gallons of fresh fuel (went with higher octane hoping it might do something) and managed to get it to start idling once but rough and around 500RPM throwing P0300 as well. I have water in my exhaust, but it doesn't smell sweet so I don't think it's coolant.

I'm thinking it's the bad gas honestly, and feel like I should drain the tank and try only fresh fuel, but I'm loathing dropping the tank with 10 gallons in it again. Any way to run the fuel pump itself to drain most of the fuel without the engine running?

If you need any more info, I'll do my best to provide as quickly as possible.

Sorry for the rambling post, it's 5AM and I've been up all night trying to rack my brain for solutions. I'm looking forward to figuring this out, this old Jeep's still got life in her yet, I just know it.

Thanks in advance and for all the info, docs, and insight I've gleaned since embarking on this undertaking, or in the past as I've searched here for much info on my XK.
 

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@glitchmodule Welcome to the forum! And please make an introductory post in the New Member Section when you get a chance. Thanks. As to your problem, maybe you could siphon the gas out?

.
 

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Discussion Starter #3
@glitchmodule Welcome to the forum! And please make an introductory post in the New Member Section when you get a chance. Thanks. As to your problem, maybe you could siphon the gas out?

.
Hey, thanks for the reply. I'm going to give that a try tomorrow most likely when I've got some help, as I've got a baffle at the tank where the fill port attaches. No luck getting a siphon past it when I changed out the pump, had to remove the pump before I could empty the tank...hopefully the lock ring doesn't put up as much a fight this time.

I'll put together a more appropriate new member post tonight as well.
 

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Discussion Starter #5
Hey fellow XK enthusiasts,

My name's Rob, I go by Glitch or any variation of Robert excluding Bob and its derivatives (that'd be my father) and I'm coming at you from Pittsburgh, Pennsylvania in the United States.

I own a 2007 XK Sport in light Graystone, 3.7 V6, 4x4 QTi.

She was sold to me non running and having sat for a few months, but I've got her able to start now, albeit with p0300 and p0203 throwing (random misfire, and fuel injector open cyl3). I'm hoping I can find the issue with your help, and we can get this old girl back on the road for many more miles of service. She's in great shape for her age and it'd be a shame to put her out to pasture just yet.

I look forward to speaking with yinz, and hope you're all having a great day.

Cheers,
Rob M.
 

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Discussion Starter #6
Just an update, I got the coils in and gave the throttle body a good cleaning. Fired her up and while it's definitely more responsive (those old coils had seen better days) she still chokes. I've got a new code as well, p0203, so I went ahead and ordered a new set of injectors that I'm hoping arrive in a timely fashion. In the mean time I'll be dropping the tank to drain it again and refilling with fresh gas to see if that fixes her. Here's hoping.
 

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Discussion Starter #8
Nice to see you Glitch! And about your misfire problem. Have you checked the ignition coils?
Hey there Ronin,

I changed them out today, and while they were definitely on their way out, the issue persists. So far I changed plugs that were nice and carbeurized, coils, oil and filter, battery which was 10 years old, and fuel pump. I cleaned the throttle body as well, and have checked the air filter and intakes for obstruction. I've got some freeze frame data from one of my tests, but my scan tool is cheap. Here's the FF data:

---------BEGIN FF DATA---------
Fuel sys1: CL
Fuel sys2: CL
Calc. Load: 75.2%
ECT: 93.2°F
STFT B1: -21% //P0203 related?
LTFT B1: 0% //hasn't run enough to set this
STFT B2: -5.4%
LTFT B2: 0%
MAP: 19.1inHg
Eng RPM: 466
Spark Adv: 5.0°
IAT: 82.4°F
TPS: 21.1%
Command EGR: 0.0%
EGR Error: 0.0%
Command evap: 0.0%
BARO: 28.6inHg
ECU Volts: 14.28V
EQ Ratio: 1.000
Rel. TPS: 10.1%
Ambient: 77°F
TPS B: 21.5%
ACC pedal D: 19.2%
ACC pedal E: 9.4%
Command TAC: 10.5%
----------END FF DATA----------
I still have the p0300 after clearing, p0203 is gone however.

I've got new injectors on the way, as I imagine they're probably an issue, at least cyl3's and I found a set of 6 reasonably priced, so I'm going to replace them all to be safe. I'm also planning on draining the tank and refilling it with fresh gas as well.

I noticed the ground strap that is on the passenger's side is broken and so oxidized that it looks like Lady Liberty's leg hair. I'm looking for where that attaches behind the engine to fix that up as well.

If I'm being entirely honest, while being mechanically inclined, I have somewhat sparse experience with automobiles. I've been taking stuff apart and putting it back together as long as I can remember, but I'm still learning when it comes to cars, so I only understand some of the freeze frame data. If you can glean anything from it I'd love to hear it.
 

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Vehicle repair can be a little more nuanced than other things. The combination of electrical and mechanical on top of a fuel system can be a real hill to tackle especially when trying to narrow down a problem. The ground strap reminds me when I found a ground wire from attached to my PCU, the other end look like it had burned/melted off. I didn't even realize it was an issue because it was out of sight. I reattached it to the engine block and it made no difference so I'm not even sure what was up with that. Maybe check the wiring for each coil?
 

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Just an update, I got the coils in and gave the throttle body a good cleaning. Fired her up and while it's definitely more responsive (those old coils had seen better days) she still chokes. I've got a new code as well, p0203, so I went ahead and ordered a new set of injectors that I'm hoping arrive in a timely fashion. In the mean time I'll be dropping the tank to drain it again and refilling with fresh gas to see if that fixes her. Here's hoping.
@glitchmodule Thanks for keeping us up to date!

.
 

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Discussion Starter #11
Vehicle repair can be a little more nuanced than other things. The combination of electrical and mechanical on top of a fuel system can be a real hill to tackle especially when trying to narrow down a problem.
This I've come to know all too well haha...luckily I'm not entirely on my own, as my father's fairly knowledgeable, and I've got his insight to lean on.

The ground strap reminds me when I found a ground wire from attached to my PCU, the other end look like it had burned/melted off. I didn't even realize it was an issue because it was out of sight. I reattached it to the engine block and it made no difference so I'm not even sure what was up with that. Maybe check the wiring for each coil?
It's definitely broken, not burned or charred, I don't have a picture at the moment, but it's a pretty clean break, 13 years of corrosion have taken their toll on the copper for sure.

I'll be taking the coils back out Wednesday when the injectors arrive, so I'll take that opportunity to make sure everything's in ship shape, wiring-wise.

From the freeze frame data, specifically the STFT, I think either I'm not getting spark or not getting fuel on the driver's side fuel rail. Possibly cylinder 3, but i wouldn't rule out 1 and 5 without further testing as well.

Here's hoping i can get it sorted this week haha.
 

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Hey Everyone,

New around here (I've lurked, but haven't posted yet...you've all already helped me more than I can express.) Recently purchased a 2007 XK 3.7 with QTi that wouldn't start, I replaced the fuel pump and got her to fire up, but she's not happy.

Good news is I don't hear anything that sounds painful, just sputtering, and vibration. Bad news is I've got the oh-so-helpful P0300 with no other codes. I put in new plugs as the old ones were nice and charred. I'm going to pick up some new coils later today, and see if they sort it out.

The jeep sat for almost 3 months before I got it, and while I didn't add all of the gas that was in the tank back, I did add about 5 gallons after the pump change somewhat absent-mindedly. I've since added a bottle of HEET and 5 gallons of fresh fuel (went with higher octane hoping it might do something) and managed to get it to start idling once but rough and around 500RPM throwing P0300 as well. I have water in my exhaust, but it doesn't smell sweet so I don't think it's coolant.

I'm thinking it's the bad gas honestly, and feel like I should drain the tank and try only fresh fuel, but I'm loathing dropping the tank with 10 gallons in it again. Any way to run the fuel pump itself to drain most of the fuel without the engine running?

If you need any more info, I'll do my best to provide as quickly as possible.

Sorry for the rambling post, it's 5AM and I've been up all night trying to rack my brain for solutions. I'm looking forward to figuring this out, this old Jeep's still got life in her yet, I just know it.

Thanks in advance and for all the info, docs, and insight I've gleaned since embarking on this undertaking, or in the past as I've searched here for much info on my XK.
@glitchmodule; Welcome to the forum. Post some pics of your Commander when you can;

Here are some links if you need to order any more parts for repairs or upgrades to your XK;

Chrysler/Jeep Factory Parts: https://www.factorychryslerparts.com/

North American Parts: https://northamericanparts.rpmware.c...unt/login.aspx

JeepinByAl: JBAoffroad.com

JustforJeeps.com - https://www.justforjeeps.com/

Rough County lift kits - Suspension Lift Kits, Body Lifts, Leveling Kit, 4x4, Jeep, Chevy, Dodge, Ford, Off-road Truck | Rough Country Suspension Systems®

4 inch XK Superlift;
AFE: Advanced FLOW Engineering | Engineered Adrenaline

CARiD.com - https://www.carid.com/?gclid=CjwKEAj...NrrxoCEBbw_wcB

Bilstein shocks & struts - Home

WAM Custom Bumpers - https://wambumpers.com/

Jeep Steel Bumpers
4WheelParts.com - Truck Parts & Jeep Parts - Lift Kits, Winches, Tonneau Covers, Tires, Wheels, Bumpers, Performance ? 4 Wheel Parts

RockAuto - https://www.rockauto.com/en/catalog/...catalog%2Fjeep

Also, please read the new member required reading below if you haven't done so already; lots of good information in here;

REQUIRED READING!!! New Member Introduction post & other important new member info.

Thanks & again, welcome aboard.
 

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Hey fellow XK enthusiasts,

My name's Rob, I go by Glitch or any variation of Robert excluding Bob and its derivatives (that'd be my father) and I'm coming at you from Pittsburgh, Pennsylvania in the United States.

I own a 2007 XK Sport in light Graystone, 3.7 V6, 4x4 QTi.

She was sold to me non running and having sat for a few months, but I've got her able to start now, albeit with p0300 and p0203 throwing (random misfire, and fuel injector open cyl3). I'm hoping I can find the issue with your help, and we can get this old girl back on the road for many more miles of service. She's in great shape for her age and it'd be a shame to put her out to pasture just yet.

I look forward to speaking with yinz, and hope you're all having a great day.

Cheers,
Rob M.
Hopefully this will help you out, as you're chasing your gremlins @glitchmodule;


 

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I had a 1999 Grand Cherokee for awhile, and I did find a way to drain the tank, by disconnecting the fuel line from the injectors, and jumpering the fuse block to energize the pump. I took out over 5 gallons that way.
 

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Discussion Starter #15
It's been a long week...tried some things to no avail, put on a new throttle body, replaced cam and crank sensors just in case, verified wiring...then I broke down and bought a borescope.

Found coolant in cylinder 4, not a ton, but that's not supposed to be there...Hopefully it's just the head gasket, but I worry that the head may be cracked or warped. So it looks like I've got my work cut out for me... I'm asking around for decent mechanics around me (Washington/Fayette county) but it's probably going to be a pretty penny. Here's hoping I can get her on the road again.
 

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weellll...by the time i saw this thread, you're already well along your way! p0300 is a multi missfire code, so kinda generic but here's the FSM info:
Set Condition:
The threshold to set the fault is application specific; it is tied to the level of misfire that will cause emissions to
increase to 1.5 times the standard or in some cases 1%. It is always a two trip fault above the calibrated RPM.

It takes 1 soft fail to set a malfunction and two trips to set the MIL. Three good trips to turn off the MIL.

STFT is short term fuel trim....this is just a parameter of the fuel system trying to keep that optimal fuel ratio. This number can be all over the place at idle, it changes live while you're driving.

The ground strap (at least on the 5.7s) goes back to a small threaded rod on the firewall, above where the heater and a/c lines go through. There should also be a ground wire coming from the PCM block to this same point.

SOOO, even though you've found coolant in a cylinder, which is never a good thing, i don't think anything else you've found is major. The coolant is most likely triggering that p0300 code. But depending on how far you get with this, i'd suggest replacing the O2 sensors as well since those are pretty well aged now and do have a pretty big effect on the overall system- at least the upstream 2 sensors if you have 4.
 

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Discussion Starter #17
weellll...by the time i saw this thread, you're already well along your way! p0300 is a multi missfire code, so kinda generic but here's the FSM info:
Set Condition:
The threshold to set the fault is application specific; it is tied to the level of misfire that will cause emissions to
increase to 1.5 times the standard or in some cases 1%. It is always a two trip fault above the calibrated RPM.

It takes 1 soft fail to set a malfunction and two trips to set the MIL. Three good trips to turn off the MIL.

STFT is short term fuel trim....this is just a parameter of the fuel system trying to keep that optimal fuel ratio. This number can be all over the place at idle, it changes live while you're driving.

The ground strap (at least on the 5.7s) goes back to a small threaded rod on the firewall, above where the heater and a/c lines go through. There should also be a ground wire coming from the PCM block to this same point.

SOOO, even though you've found coolant in a cylinder, which is never a good thing, i don't think anything else you've found is major. The coolant is most likely triggering that p0300 code. But depending on how far you get with this, i'd suggest replacing the O2 sensors as well since those are pretty well aged now and do have a pretty big effect on the overall system- at least the upstream 2 sensors if you have 4.
Thanks for the reply! I'll definitely be changing out the O2 sensors while I'm this far into it. Luckily my brother might be able to help me out as far as getting the head gasket fixed, just hoping it doesn't need a full rebuild, though I'm invested enough to do it.

All I know is I have my work cut out for me...or I have a new hole in my wallet. Either way, it's gonna be fun.
 

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hopefully it is just the gasket and not a warped or cracked head.....i am all too familiar with bad heads and what road that'll take you down!
you don't happen to know much of the history of it? if it was overheated which lead to this problem? maybe before you tear everything down, do a pressure test on the coolant system and see what you can find
 

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Discussion Starter #19
Interestingly, it had a dead fuel pump, which seems to have caused it to die in flight. I replaced that right off the bat and she turned over. The previous owner told me it died at the top of the hill he lives on, he couldn't get it to turn over, crank no start, so he coasted down the hill and parked it in his driveway. Hard to tell how long he had been running it like this, though it won't even idle for more than 30 seconds, so i doubt it was this bad before the breakdown...i didn't see any coolant in the oil when we checked it out, or when i changed it out, so was hopeful it wouldn't take me down this road. Oh well, as they say, C'est la vie.
 

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I know 1 bad cylinder in the v8 runs like total crap....IF you can even get it started. So no doubt coolant in 1 cylinder of a v6 would have the same effect you're getting! Of course....if you didn't know the previous owner personally....who knows what the REAL story is....:LOL:
 
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