Check engine light comes on....then goes off after a day

[Robert Hall]

Leaving work yesterday, the check engine light in my Jeep came on (only the 2nd time in 112k miles). Got home, pulled the code, and it's an OBDII P0306 code, misfire in cylinder 6. Interesting, because I had the plugs replaced last Saturday. Since about Wednesday, I'd noticed a bit of driveline roughness when moving and when sitting at a light in gear. The check engine light stayed on since then.

Today after lunch, started and the check engine light didn't come on. Don't seem to notice as much roughness afterwards. Strange. Started and shut down twice since then, light still off.

Thinking about taking it back to the shop Monday and explaining what I saw. I haven't checked, but can I still pull the last codes even though the light is off?

[SAmadei]

Yeah, you can still recover the code.

I would double check that the wire for cylinder 6 is on correctly and is not rubbing on anything.

[Robert Hall]

Turned out to need a new coil pack along w/ 1 spark plug. Got that fixed today along w/ the passenger front window--the regulator was broken and the motor dead.

[Robert Hall]

Jeep go boom on the freeway tonight. Wouldn't restart. Got hauled 25 miles to the shop on a rollback truck. Truck driver dropped me off at home. Called a cab, went to the airport to pick up my sister's Merc 300CE to drive to work tommorow. Very tired.

[Intrepidation]

Keep us posted, I'll try to help if I can.

[Robert Hall]

No idea what's going on..was running fine, just fueled up. Got out on the freeway, up to about 60 in heavy rush hour traffic..heard and felt a loud bang, engine cut out. Coasted to the side of the road to breakdown lane (glad I was in the right lane). Tried starting, cranked, but wouldn't start. Got out, opened the hood, saw nothing amiss...looked underneath, no fluid leaking, nothing hanging down, no smoke, no hot smell..

20 min later after calling the wrecker service, got back in, it started immediately, idled normally...no check engine light, gauges seemed normal...put it in drive, went forward 10-20 feet, seemed ok. Didn't trust it to drive home 20 miles in heavy traffic, though.

[Robert Hall]

Just talked to the shop...they can't find. anything. wrong. Weird.

Maybe I got bad gas (I had fueled up about 10 min earlier) and it was a backfire and stall.

No idea.

Perplexing.

[Intrepidation]

Could be a camshaft or crankshaft position sensor. Camshaft normally throws a code but the crankshaft doesn't always throw one.

Symptoms for both are random stalling, followed by a no start condition after stall, but then it will start back up no problem after time has passed.

[Robert Hall]

Could be a camshaft or crankshaft position sensor. Camshaft normally throws a code but the crankshaft doesn't always throw one.

Symptoms for both are random stalling, followed by a no start condition after stall, but then it will start back up no problem after time has passed.

Interesting..will ask them to check those. Excluding the bang, it reminds me of what happened w/ my Mustang when it had a clogged fuel filter.

I had the differential position sensor on the rear axle replaced last year, it had a wierd stall behavior and threw a code and the check engine light came on.

Edited September 23, 2010 by Cubical-aka-Moltar

[Drew Dowdell]

yeah, what's up with that bang? Can you describe it more?

[Intrepidation]

The bang is the only thing I'm not sure about, but considering the sensors probably aren't too expensive (around $40 each, at least for LH cars), its a good place to start.

A few years ago I had to deal with a randoms talking problem that wouldn't throw a code and nos hop could locate the cause of. Based on research I did, I narrowed it down to the crankshaft potion sensor. Since had had no other inexpensive ideas and the symptoms sounded similar, I replaced it. Fixed the problem...until my camshaft sensor went a year later.

[Robert Hall]

yeah, what's up with that bang? Can you describe it more?

I've never had a backfire before, but perhaps this was one. I was driving along at about 60-65, A/C, radio on (i.e. noisy inside) and I suddenly felt a shudder through the vehicle and heard a bang..like a rough shift but much stronger. Then the engine died (silently) and I coasted off the freeway...don't think I ran over anything,the road was clear.

Edited September 23, 2010 by Cubical-aka-Moltar

[Drew Dowdell]

Fuel Injector?

[Robert Hall]

Picked it up this afternoon. Shop couldn't find anything wrong. I think I'll run some fuel injector cleaner through it.

[Intrepidation]

I suggest Seafoam.

[daves87rs]

I suggest Seafoam.

+1

[Robert Hall]

I'm thinking now it may have been low blinker fluid.

Haven't driven it all week, been driving my sister's old Merc 300CE hardtop...been cool enough in the mornings to drive w/ all the windows down and sunroof open. Fun.

[Robert Hall]

Drove the Jeep to work today (after sitting a week). Wouldn't start when I went out for lunch. Waited an hour, it started. Drove to nearest auto repair shop...thought maybe it was the battery (though the battery is only a year old)...they checked it out, the terminals on the battery cables were corroded and making intermittent contact..not well grounded. Replaced the terminals...hopefully this cures the gremlins for a while. Got the blinker fluid refilled also.

[A Horse With No Name]

Good luck getting her sorted out, Cubitar.

[Robert Hall]

The fun continues... came out of the office at 4:30, wouldn't start. Cranked, but no wouldn't start. Called the shop and the towing service. 45 min later the rollback truck shows up. The Jeep starts immediately, I back it up, pull up behind the tow truck, leave it running. 2 min later it shuts itself off. Won't restart. Hauled it 25 miles to the shop. Home now. Frustrated and tired. Will be back to the Benzes tommorow.

[Intrepidation]

Maybe you should try another shop.

Have you tried checking for codes? You can do so with the keydance. Turn the key to accessory, then ff, and do this 2 more times. On the 3rd time leave it in acc. The odometer screen will then go into diagnostic mode and display any generic fault codes it finds.

[Robert Hall]

Maybe you should try another shop.

Have you tried checking for codes? You can do so with the keydance. Turn the key to accessory, then ff, and do this 2 more times. On the 3rd time leave it in acc. The odometer screen will then go into diagnostic mode and display any generic fault codes it finds.

I should have checked the codes...I have my code reader in the car, but was too tired to think of it today..

[Robert Hall]

DF called it w/ the crankshaft position sensor. That's apparently what it is.

Shop also says I need front CV join boots (leaking) and rear brakes (95% worn)...been expecting the rear brakes, the current ones have probably 50k on them..

[A Horse With No Name]

Considering how long it's been paid for, and other than the drivers seat....you've been pretty lucky.

Glad to hear Mr Liberty blue will be back on the road soon....

[Intrepidation]

DF called it w/ the crankshaft position sensor. That's apparently what it is.

[Robert Hall]

Picked it up and drove home in a downpour...seems to be running great. They replaced the crankcase sensor, CV joint boots, and rear brakes.

[Intrepidation]

Cool, hopefully that puts and end to your issues.

[Robert Hall]

Latest fun w/ the Jeep...my sister picked me up at the airport this afternoon...on the way home, ran over some debris (that she tried to avoid) on the freeway and heard something bump around underneath....got about a mile from home (off the freeway) when the left rear tire blew out..drove a short distance on the rim into a parking lot. The entire sidewall is shredded. Called AAA and they arrived in about 10 min and changed the tire (was too tired to change it myself). Not sure if the rim is damaged or not, but my sister will be getting me a new Goodyear Fortera Silent Armor this week...

Looked around underneath after getting home, the rubber liner thingy in the rear wheelwell is flapping around, looks like it's ripped loose from the rear bumper where it was screwed to...great.

Edited October 18, 2010 by Cubical-aka-Moltar

[Intrepidation]

That sucks, not the Jeep's fault though.

[Robert Hall]

Ended up replacing all 4 tires...replacing one wouldn't have made sense, they had about 50k on them and were worn down to 4/32th...

[Camino LS6]

What I wouldn't give to have such straighforward problems for a change!

Wait... I take that back.

Tires are expensive.

[Intrepidation]

But they last a while. Worthwhile investment.

[Robert Hall]

Tires are expensive.

Ya..$799 for 4 installed.

But they last a while. Worthwhile investment.

Ya, if I can get 3-4 years out of them, I'll be happy.