Bad Signs.....

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Sirthor1881

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Well the KJ started to miss really bad here recently..I changed plugs, swapped coil packs, well when cyl #6 plug was out it had a slight green tint to it. I am thinking that the headgasket is shot. I had to add about a quart of coolant, about 3 months ago. I noticed the tank was basically empty now. There is no smoke however, I also noticed that it appears to be leaning out all cylinders. They where white colored, the gap was good though, so close to spec. But I think it may be blown now, none of the plugs or ignition swapping did any good. I bought it used, never got hot on me at all, ran smooth, and good till now. This *****. Anyone have a rough estimate on the cost to replace the headgaskets at the stealership prices? I guess it will have to go to the dealership, cause my garage is full right now. I hate taking things there.

Richard
 

JeepJeepster

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How many miles are on the Jeep? A green spark plug does NOT mean the head gasket is bad. Is the check engine light on? If it is, have you checked the codes?

The missing coolant could just be a cracked radiator, which is common for the kj.
 

kb0nly

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I hope you didnt come to that conclusion because the coolant in it is green?? *SHUDDER*

You shouldn't have that Dex Cool crap in there, HOAT type only, should be orange or gold in color depending on brand. The stuff from Napa has kind of a goldish/orange color to it and is made by Valvoline for Napa. The stuff Advance has i don't know who makes it, but its more of a dark orange, they have it now in a black jug with Advance's name on it so i don't know who makes it for them.

As JJ just mentioned check for leaks first, determine where the coolant is really going. And i would have a compression test done on it first before you rip the heads off, or have someone do that. Would suck to get that all torn down and the gaskets are ok. Compression test will tell you if you have a leak in the cylinder, and bubbles into the coolant will tell you where that coolant is going if its a head gasket.

How is the oil?? I take it you don't have coolant in the oil, easy to spot if you look down into the oil fill, should be like chocolate milk up in the head. The KJ's are infamous for their radiator problems, so check for a crack around the top hose on the drivers side, look for signs of coolant that leaked out and dried off, a bit of residue will be left around the crack or it will still be wet.

Any smell of burning coolant?? Either in the engine compartment while driving or from the exhaust out back? If your burning coolant its going to be pretty obvious. Check the small things first. I had a coolant leak that ended up being a loose lower hose clamp from the radiator and hoses being replaced, they didn't retighten after a few heat cycles.

Is the Check Engine Light (aka CEL) on at all? Pull the codes? If you got coolant going into the cylinders and its running rough you should be getting misfire codes if something is really wrong. Otherwise it could be something else, vacuum leak, dirty throttle body, dirty injectors, it can be so many things. You didnt say how many miles, how old is the fuel filter? Have you run anything through it? Try doing a Seafoam cleaning of the engine, annoy the neighbors with the great white cloud of smoke and see how she runs then.

Also what did you put in for plugs? Best bet is plain old Autolite Platinums AP3923 for 02-04, you didnt mention model year, but dont bother with double platinums or triple fires or any fancy crap like that, just plain close to stock plugs and then run it for a while and see what happens.

My best advice... Seafoam it and change the plugs again to new Autolite's, and top off the coolant and keep a close eye on it until you find the leak for sure. As long as its not making any oil, an old term meaning no coolant in oil and the level isn't going up and no chocolate foam, and its not overheating, then the leak is not in the engine. A head gasket leak wouldn't make all six cylinders run lean also if thats what you mean.

Could be a bad IAC, Idle Air Control, as well. Is the rough running mainly noticed at idle or all engine speeds?

Sorry for the lengthy post but as you can see there is a lot more to this and more details would help us help you.
 

Sirthor1881

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The jeep has arond 73K on it, Auto Limited 2003.

I pulled the codes, and I have a 0442, and 0300, and 0301, 0306. I know the 0442 is something to do with the evap. system. I noticed a cracked hose by the fuel tank so, its either that or the gas cap. But that doesn't concern me to much.

It used to only miss real bad when it was extremely cold, but it would warm up, then go away. I am losing coolant to somewhere, I will look around it really well this weekend. I changed out the plugs with some Autolite Double platinums. I set the gap to .040 like the tag says under the hood. This didn't help anything. It starts to miss really bad once the trans shifts into second and it loads up the engine. If it starts to miss the codes that show up are multiple misfire, and misfire on cyl. 1 cyl. 6. I assume that those two fire together?

No I was not assuming that the green was from the coolant. I had just replaced the factory plugs about 2,000 miles ago that the previous owner left in it. It ran fine after that until now. I have not changed the fuel filter, but I put a bottle of Lucas Fuel Treatment in the tank. I may try the fuel filter next. Does anyone out there know what the resistance should be on the coils? The oil is not milky, and its not smoking like hell so maybe it isn't blown. I will check for an external leak. It ***** because I had to leave out of town and I won't be able to mess with it until the weekend.

Thank You.
Richard
 

Sirthor1881

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Oh yeah its a little rough at idle, noticeable, but really misses bad around 2k and up. Possible crank sensor issue maybe?
 

kb0nly

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Oh yeah its a little rough at idle, noticeable, but really misses bad around 2k and up. Possible crank sensor issue maybe?

Ok now we got some good info...

I would definitely hunt for leaks then, i doubt your losing coolant into the combustion chambers via a leaky head gasket.

The missing is under load, points to a fuel system or ignition system problem, either not enough fuel or not enough timing advance. Could be a crank or camshaft sensor. There has been a couple guys on here with similar driveability issues and misfires which were solved with a new Camshaft Position Sensor, its up on the drivers side head near the front and fairly easy to change.

I would also do a Seafoam treatment on the motor, more effective than dumping something into the tank. I don't know the coil resistance off hand, it is possible to have two bad coils, not likely, but possible. Did you try swapping 1 and 6 with 2 and 4 or something like that and run a few days to make sure the codes don't shift to the new location for the faulty coil? Make sure you clear the codes after swapping the coils and then run for a day again to check.

I will see if the FSM shows the resistance.
 

JeepJeepster

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P0442 Evaporative Emission (EVAP) System Small Leak Detected (often this is a loose or bad gas cap!)
P0300 Engine Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0306 Cylinder 6 Misfire Detected

Id do a compression check on those cylinders at least.
 

kb0nly

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P0442 Evaporative Emission (EVAP) System Small Leak Detected (often this is a loose or bad gas cap!)
P0300 Engine Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0306 Cylinder 6 Misfire Detected

Id do a compression check on those cylinders at least.

Also that damn hose back by the EVAP canister has been reported by a few as dried and cracked... So check gas cap or even replace and trace all the EVAP lines from front to back.

But the EVAP wouldn't cause the other problems your seeing, just popping a CEL to let you know you got a leak. Although, and its a stretch, couldn't this cause a change in manifold pressure?? I'm not really versed in the EVAP system on the KJ.

From what i understand it collects gases from the crankcase and then the EVAP purge solenoid opens to purge the system by allowing the engine to suck in the contents of the EVAP canister right? Thats how the system was on the Neon we had, i guess in theory if you have a leak there it could be like having a vacuum leak but it would have to be after the solenoid because otherwise the solenoid can still close to meter the airflow.... Anyone have a better understanding on that chime in! I will have to read the FSM on it.

Also agreed, do at least a compression test on those two cylinders. I still don't suspect a head gasket.

Also you asked about firing order...

The cylinders are numbered from front to rear with the left bank numbered 1, 3, and 5 and the right bank being numbered 2, 4, and 6.

The firing order is 1–6–5–4–3–2

So it is interesting that its missing on 1 and 6 when they are the first two in the order. But since they are on different sides of the engine its not likely related to a head gasket.
 

rockymountain

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Since 1 and 6 are misfiring I would suspect the Crank Position sensor because they fire in succession. Green plug means oxidation? maybe a vacuum leak within a bad intake gasket? The two may be unrelated and just coincidental.


Just thinking out loud here...
 

kb0nly

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Since 1 and 6 are misfiring I would suspect the Crank Position sensor because they fire in succession. Green plug means oxidation? maybe a vacuum leak within a bad intake gasket? The two may be unrelated and just coincidental.


Just thinking out loud here...

I'm thinking a sensor throwing off the ignition timing as well....
 

Sirthor1881

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Okay, I will check all that stuff out this weekend when I get time. I appreciate all the help, I will let you know what I find. I really appreciate it.

Richard
 

Midgear

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hmm.. I'm just gonna throw this out there at random, so if it sounds stupid, just ignore it.

I did a seafoam treatment on my 3.7 a few days ago.. and it misfired like HELL and it went into limp mode, it would not pass 3k RPM while revving in park or neutral, the rev limiter set itself down to 2800 RPM. engine light was flashin' at me, it sounded like a lawn mower when revving, it was awful.

I know that unplugging the battery will reset your engine light, so I figured it'd reset the coils. it seemed to me that since it detected a misfire, it actually cut power to the coil that was sending the spark to the cylinder that was misfiring.. throwing the MIL (malfunction indicator light, or check engine light)

unplugged the battery, had a cigarette, plugged the battery back in, fired it up, absolutely shit out this giant cloud of smoke, and it ran like brand new.

not saying that unplugging your battery is gonna solve your problem.. but I'd try it out and see what happens.
 

Sirthor1881

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Well, today I went out, and cleared all fault codes using my Matco Scan Tool. All the codes went away. I drove it around for about 20 mins. it idled smooth, and ran fine no stumbling at all.

I need to get an adapter for pressurizing the cooling system, all mine don't fit. Then I can check for an external leak.

I guess, I will drive around some more to see how it does. I may just end up replacing the crank sensor for good measure.

Thank you all for the help.

Richard
 

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