I've got a 2000 Cherokee Sport (XJ, I'm told), 4.0L inline 6 4x4. Had my valve cover off the other day (CCV breather complications) and when I closed everything back up and turned the key, everything seemed groovy. Drove 8 miles into down (windy canyon road, 35-55 mph), stopped to grab something from the gas station, and then went through a drive through. After I finished eating my food in the parking lot, I started old JeeP back up , and that's when things got dicey.

Took a little longer than usual to turn over, and sounded like it was struggling to do so. Engine was shaking pretty hard at idle, white smoke was sputtering out of the exhaust, accompanied by dribbles of fuel. Oh, and the check engine light came on.

I decided to see how it drove to the grocery store across the street (intended destination, and easier location for the likely auto-club tow) and the engine light started flashing. The manual foretold great misfortune, so I went with the tow after all.

So that's where I'm at. Wondering what the problem is, and how I can fix it. I've got a couple of suspected causes, but I'm new to mechanicry, so I'm reaching out here to suss them out.

There were a few complications while I was replacing the valve cover. First, I lost one of the bolts in the back that I ended up finding in a bundle of cables/wires running back on top of the transmission (you don't even want to know how long that took me to recover), so there's a chance I may have jostled something out of position in the wiring/connections behind the valve case and above the transmission.

... and then I snapped a bolt, and spouted some curses. In the process of loosing that bolt, I had to remove the coil pack, and it was something of a struggle to get it back into place.

Now, through parts of this process, I had to literally climb up on top of the engine area, taking care of where I distributed my weight... except for when I accidentally cracked what nearest I can tell is the fuel injector wiring harness. Plastic casing that runs along the driver's side of the valve cover, out of which the fuel injector pigtails feed.

Recent Jeep history: Had what turned out to be a failing freeze plug that I replaced with a rubber one, after getting a metal one which turned out to be a bit too small. Before I discovered the freeze plug issue, I overheated a couple times (the second being pretty significant), and there were also a couple instances of a load whistle that would go away when I depressed the accelerator.

Thought everything was cool with the freeze plug fix, and after about a week of driving about 150-200 miles, I decided to change out that CCV breather (contributed to a failed smog), and the elbow cracked...

Which brings us up to speed.

Any thoughts on what I can do to get JeeP up to speeds higher than parked? I'm really hoping it's just a plug/wire that came loose, what with my limited access to funds and specialized tools.

 

Flashing CEL means a misfire, which you need to take care of asap. Driving it with a misfire can cause engine damage. Moving the coil pack you may have cracked it somehow, contributing to the misfire, maybe. Engine shaking? Partially clogged cat, again maybe. White smoke makes me think coolant, but could be fuel as you found dribbles, i assume from the tailpipe? Could be a stuck injector. Passing too much fuel, or even coolant (or both) will kill the cats eventually. The coolant will ruin your o2 sensors as well. Long crank times could be anything. Bad grounds or even an oil soaked starter can do it, as can a damaged cat (partially clogged). You say "it overheated a couple times (the second being pretty significant)". A cracked head is possible. Check your coolant level and condition, and give it a compression check. Check your vacuum lines and even fuel pressure. If it were mine, thats what i would do.

Do you have a code reader or scanner? You may have more than one code. I use an Actron Cp9670.

 

Just found a code reader lying around earlier this afternoon (well, yesterday, I suppose), about a minute before realizing the was a thousands-acre fire just over the hill... so I'll be plugging that bad boy in after I get some sleep, now that it seems like the coast is clear.

If there was trauma to the coil pack, it'd likely either be the connection in the back (or maybe where the pigtail splits off from the larger group of wiring), or the 2 frontmost nubs. I had to bend them into position a little, whereas I probably should have just removed the small hose running from the thermostat back to the heater core (I was getting pretty tired by that point), which I did after I got back home via tow, when I checked that the pack had slotted into all the plugs correctly.

Oil-soaked starter and damaged cat seem like something I'd have noticed sooner, I think. Fluids are at good levels, and oil's quite clean - which would rule out the cracked head, right? And also something I'd have noticed sooner?

Now... having just replaced a freeze plug, that finally took on the third attempt (first one 'they' sold me I've declared the wrong part... got three of them, cause they were cheap, and that's all they had; ended up going with the expandable rubber), and being rather broke, I've yet to put coolant back into the mix, and it's presently filled with distilled.... but I'm in CA, in the summer, so that should be fine, right?

Already planning on seeing if I can find a compression gauge, and I'll look into how to check the fuel pressure.

 

Codes that came up with the OBD were P0505 and P0122. I'm gonna check them out in more detail after I've had some sleep. Been pretty intense with the fire out here, and it's long past time I get some shut-eye.

... any advice relating to these codes?

 

Hmmm. Those codes are for your IAC (idle air control) and TPS (throttle position sensor).

Testing the TPS is easy, and best done with an analog multi-meter. Here's how.

IAC is often in need of a good cleaning. Use Throttle Body Cleaner, not brake or carburetor cleaner.

But since this happened suddenly, my guess is you broke something. Maybe even the TPS. Good news there, they are easy to replace, and not horrifically expensive.

Might just be a connection problem, too. I'd start looking for loose connections or broken things. I know you said you were careful, but it would be easy to damage something without realizing it.

 

Solved! (anyone know how I can edit the title of this thread to reflect such?)

Turns out I'd gotten some moister on one of the spark plugs when I pulled the heatercore line to replace the coil pack. That's what was causing me to have unburnt fuel in the mixture. Basically just burned it off by manually tweaking the throttle.

... now I just have to figure out why both of my ignition keys are intermittently failing. Let the searching begin!

 

"Basically just burned it off by manually tweaking the throttle."

I think you'll be back...

 

Agreed.

 

I've put about 300 miles on it since the problem went away, and have also passed a CA smog...

Anything other than the simplicity that hints of my return?