Super ruff idle and dies when pedal is pressed

Super rough idle and dies when pedal is pressed

Hello guys! This morning I went to the gas station next to my house on my 05 limited 145k miles on it, oil changes every 3,000 miles since it got out of the dealership, turned it off, when I went to start it, it could barely survive idle and would die if I pressed on the pedal, I had to press on the pedal about half way then crank it so it would not die, I got it to 2000 rpm and it was not rough but I could feel it was not "clean".

I got home pulled the iPad and the "OBD Fusion" diagnostics app with the ELM wifi scanner and these were the results:

1. Checked for codes but nothing.
2. Checked TPS and it is normal 14%-74% smooth through the whole range.
3. Cleaned ICV and Throttle (were dirty but not much change).
4. Installed new spark plugs (got a little bit better but not much change).
5. Checked vacuum leaks and nothing.
6. Pulled coils one by one and same result on all (idle got worse on each individual test)
7. Air temp OK.
8. Coolant temp OK.
9. At 2,000 RPM O2 sensor 1 got kind of crazy while sensor 2 was around .9
10. After all the tests I reset the codes and checked and again no codes.

Old spark plugs on driver's side were very dark while plugs on drivers side were a bit lighter in color but not the desired color.

Could it be clogged cats? I'm stumped... I am thinking about loosening both sides of the exhaust manifold where they meet the cats and see if idle returns. Noise is not a problem since I got no neighbors LOL...

Any help will be much appreciated...

Did it act up before or after you got gas? If after, maybe purge valve related? Have had similar things with my LR3...bucks after getting gas sometimes.

After I got gas... What are the symptoms for the purge valve? Does it trigger codes?

Generally should, but I've had my LR3 buck without showing codes. There's some test you can do with them on a bench, not exactly sure what it is, could probably google it. The KJ purge valve is that thing clipped onto the fuse block by the battery. Easy to get to unlike the LR3 one that's up against the firewall.

Checked... Also in good shape... Still leaning towards a clogged cat converter which none has ever been replaced...

Hope is not a valve or the timing chains... What kills me is... No codes!

Dirty fuel?

Is the a/c supposed to blow to the feet for about 45 seconds then slowly switch to the upper vents when turned on? I ask because I read that these vents are vacuum operated. If that vacuum is bad could it cause the rough idle problem?

Faulty belt tensioner?

Jcdes said:

Is the a/c supposed to blow to the feet for about 45 seconds then slowly switch to the upper vents when turned on? I ask because I read that these vents are vacuum operated. If that vacuum is bad could it cause the rough idle problem?

Click to expand...

yes but not to the point where it wont rev, and the directional door can be slow to get to its home, but once its there if there's a vac leak of that caliber behind the controls, youd probably be looking for the snake hissing under your seats.

LOL... You're right... I just read this elsewhere, it's an 03, mine is 05 but still has me worried:

"3.7L 1 entire bank refused t run. No check enging light. No code to read. Has spark, fuel, valve timing right on, crank sensor OK. Compression 10-15lbs lower in #6 cyl, but still in range.
THE FIND: swap valve springs from #6 with other cyl., and compression variation followed. VIOLA!! replaced springs & locks, System resets itself and all cyls firing and runs excellent.
ONE WEAK VALVE SPRING- screwed the computer into compensating EGR, O2, fuel delivery WITH NO CODE, NO CK ENGINE LIGHT. BUT SHUT DOWN ONE BANK OF CYLINDERS WITH EXCESS FUEL DELIVERY. **Not the computer's fault*
I did not discoer the solution. A friend/top shelf Tech isolated faulty spring, w/o codes or ck engine signal."

Damotee said:

Faulty belt tensioner?

Click to expand...

Hmmm... Did not think of that... But wouldn't that generate a code?

I think it's time for some voo-doo, I need a live chicken... LOL

Jcdes said:

Hmmm... Did not think of that... But wouldn't that generate a code?

Click to expand...

Probably not

At 2,000 rpm cats and pipes are getting red towards the rear, the driver's side more than the passengers side. I'm gonna loosen up both sides see if the problem stops. Again I got no codes on the scanner and no codes doing the "On" "Off" "On" "Off" "On" switch process.

My Jeep was running like yours. Started out as a rattle sound when idling and also when I tapped the gas pedal. Eventually, the Jeep began to cough and splutter to the point where I thought I had water in my fuel. Swapped out the belt tensioner and problem solved.

Edit ; I also swapped out the serpentine belt at the same time.

I don't hear a rattle at all, the serpentine and tensioner have less than 1,000 miles. Like I said it has me stumped except for the fact that the cats are the factory ones from 2005 with 145K miles on them. I had been experiencing power loss going uphill and on the highway it felt like I needed to press the pedal further down in order for it to go at the speed that I'm used to driving. That's why I'm still leaning towards the cat replacement. Has anybody tried a no-cat setup with a rear 02 sensor simulator or plug extensions??? It would be a temporary rig while the cats arrive. I'm gonna hollow them out to see if the problem gets solved.

Well... My wife had emergency surgery so I had no time until today to work on the liberty so I did a compression test I got 175 on 1-3-4-5-6 #2 was gone... Pulled the valve cover and sure enough the rocker for the intake valve fell to the side without damaging anything (luck I guess). The valve is not coming all the way up I'd say it has about 1/4 inch to fully close. I guess the seat dropped... I used an endoscope camera to look inside the chamber and the piston looks fine. I guess I'll pull both heads out have them rectified and refreshed and install new timing chain and oil pump while I'm in there... BTW both cats were clogged, I guess this caused the issue...

Update: Seat dropped, held valve a little bit open, rocker fell off so the valve never moved afterwards avoiding further damage... Lucky I guess...

Working perfectly... On the road again...