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Discussion Starter · #1 ·
Hey all...First post. I have been trolling the forums and found some great info thus far but I have a problem with my Jeep.

OK, I bought this 2001 Jeep TJ with 55K miles on it. It runs great but if I go over,say, 2800-3000RPM the engine sounds different -FLAT- and it blows smoke like there is no tomorrow! Under, say, 2300RPM it runs great but lacks power. No codes thrown but I can chew through oil like a fat kid and a bowl of smarties! It almost sounds like it is grabbing WAY TOO MUCH fuel...but it could be the fact that it is trying to burn soooo much oil. I have been entertaining the possibility of oil being sucked out through the valve cover vaccuum line at higher RPM and maybe the coil pack being 'pooched'. Of course this is just me thinking of any other possibility besides the rings being screwed. No smoke at start up and tooling around at 2K rpm....also seems to have more power loss the longer it runs.
Just hoping someone can provide any info to possible causes..the smoke is while ON the gas, not after being on the throttle at high RPMs.
Thanks to any who can offer any thoughts or potential issues...on a side note, thinking the inevitable...anyone have a good 4.0L for sale in Manitoba, Canada? :mad:
 

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Sorry, I can offer no info on this one. I am sure others will chime in soon with some helpful advice.
 

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Check your PCV.
 

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Discussion Starter · #4 ·
No PCV valve...just the plastic elbow at the back of the cover to the intake...it is clear and the front cover connector to the air filter pipe..clear as well.
 

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Discussion Starter · #5 ·
Should also add the plugs look good too. Anyone? Any ideas?
 

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The color of the smoke will tell you a lot. IIRC white=water being burned, and blue=oil being burned.
 

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Discussion Starter · #7 ·
Hey 03 Rubi..Thanks for the reply...sorry I did not mention it earlier but the smoke that covers the landscape behind me when I rev it past 2800ish RPM is definitely blue/black and smells like oil. When I first got the thing it smoked BLACK like it was rich...got codes, 02 sensor preheat...traced/repaired/cleared and now i burn oil...and i mean A LOT of oil..it is not leaking and if I run to 3K RPM for the shifts, I can burn 1 quart in 45 miles..No smoke at idle, no smoke touring around 2k rpm..but spin it up and WHOA!!!!
 

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Sorry to hear that. Sounds like you have some expensive repairs to make. Any kind of warranty?
 

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Discussion Starter · #9 ·
Sorry to hear that. Sounds like you have some expensive repairs to make. Any kind of warranty?
No warranty...I am just having to rebuild this JEEP from the ground up it appears. Sucks to be me I guess..Thanks though..
James
 

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If you end up rebuilding the motor ... Look into make it a stroker ... See If you like that idea.
 

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Have you checked to see if there is an obstruction in the exhaust system causing back pressure in the engine. Higher RPMs more pressure. Just a thought.
 

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Discussion Starter · #12 ·
Have you checked to see if there is an obstruction in the exhaust system causing back pressure in the engine. Higher RPMs more pressure. Just a thought.
OK, I will bite..Visually, all is good...but what about the CATS? How would I know if those little buggers are causing grief? And it is weird...today I got home, spun it to around 4k in the driveway a couple of times...little smell, no real noticible smoke of any kind...but tomorrow, I may do that and FOG the entire neighbourhood!!! and for sure, it is BLUE and smells of oil.
 

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Smack the cat a few times. If it rattles it's bad.
 

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Discussion Starter · #15 ·
herbster said:
You sure your buddy didnt get tanked up and put diesel in it by mistake. SEEN THAT HAPPEN BEFORE, NOT PRETTY.
Haha.... Hmmm that would suck. But no, not a diesel issue. :)
 

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Discussion Starter · #16 ·
Well I popped the cover off and had a look. Everything is clean.... That is too bad actually, I wanted something to jump out at me. Baffles were good, minimum oil in the air pipe with a little touch of sludge at the throttle body. The CCV was clean and obstruction free..... But very oily, like drippy with oil (normal?) The metered hole on the end, are there different sizes for different motors? Wonder if it is too large an orifice? I can probably YouTube a video of the issue if anyone thinks seeing it happen would help with a potential solution.
Cheers!
 

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Back in the days of ole, it would be a sign of time for a rebuild. Sounds like rings or valves.
Keep checking the simple thing checks before laying out the big bucks for a overhaul. If it wasn't for the smoke being black, I would think head gasket. Which is not uncommon on a 4.0 if over heated.
On the good side, the 4.0 is a tough motor, maybe yours is either a lemon, or more likely not properly maintained. There are a number of them out there with 250,000 miles on them and going strong.
If you do have to fork out the big bucks for a rebuild, make sure you shop around. The cost can be very wide from one shop to another. Ask for recommendations.
Best of luck to ya,
 

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Might be worth a shot here, but have you done a compression check and (I think its called) a bleed off check? A compression check will obviously check compression in each cylinder, individually, one by one. Each cylinder should be within a specific tolerance of each other. For example, if cylinder #4 had is supposed to have #100 psi but reads #97 psi, cylinder #6 should be within a specific tolerance of 97 psi, +/- the tolerance for your engine. You said you have loss of power. Maybe you have a small hole in a piston? Happens with detonation. That will cause loss of power and depending on the size of hole, the amount of oil being burnt. Trust me, I know. Had a pinky sized hole blow through my #4 cylinder. Lost all sorts of compression and if I layed on the gas, it became a neighborhood smoke screen.

A bleed off check is kind of the same as a compression check but tests the rings. This will check for blow by. Ie, burning oil. Any competent shop can do both tests. If you can get the tools, you can do it yourself too. Easy as changing a sparkplug, one at a time. If your piston rings are shot, suggest a brand new set for all cylinders.

If you must pull the engine, consider rehoning the cylinder sleeves, heat sinking the block, new forged pistons and high end rings like Mahle, if available.

Keep us posted
 

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Discussion Starter · #20 ·
Might be worth a shot here, but have you done a compression check and (I think its called) a bleed off check? A compression check will obviously check compression in each cylinder, individually, one by one. Each cylinder should be within a specific tolerance of each other. For example, if cylinder #4 had is supposed to have #100 psi but reads #97 psi, cylinder #6 should be within a specific tolerance of 97 psi, +/- the tolerance for your engine. You said you have loss of power. Maybe you have a small hole in a piston? Happens with detonation. That will cause loss of power and depending on the size of hole, the amount of oil being burnt. Trust me, I know. Had a pinky sized hole blow through my #4 cylinder. Lost all sorts of compression and if I layed on the gas, it became a neighborhood smoke screen.

A bleed off check is kind of the same as a compression check but tests the rings. This will check for blow by. Ie, burning oil. Any competent shop can do both tests. If you can get the tools, you can do it yourself too. Easy as changing a sparkplug, one at a time. If your piston rings are shot, suggest a brand new set for all cylinders.

If you must pull the engine, consider rehoning the cylinder sleeves, heat sinking the block, new forged pistons and high end rings like Mahle, if available.

Keep us posted
Leak down test would be the next thing I guess. That is a good call. I seafoamed the crap out of it through the brake vac line...now THAT is quite a SMOKE SHOW!!! haha..Anyways, today I was out with the Jeep and parked in the driveway..hopped out while it was still running and reached in with my hand and wound it out to 4K numerous times...Today, I could not get it to smoke blue from oil, but the smell of FUEL was there big time and a rich smoke (blackish) from the pipe...In the water puddle that accumulates under the pipe you can see little black puddles forming as well. Past 3000RPM, the engine sounds different and the RPM hangs a bit upon release of the throttle at those higher RPMS. No CEL codes thrown. Pulled plugs again, they look good (4 and 5 have a 'bit' of dark color near the bottom of the insulator).
James
 
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