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Unread 11-14-2012, 10:28 PM   #1
Ripper3494
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6.0 vortec wont reach high rpms

so i don't really know where to put this so i figured i'd stick it here. driving around town and nice with the throttle my engine runs fine as far as i can tell, but when i get on the gas it sputters around 5000rpms, the rev limiter is around 5500. not that this is really a huge issue in a jeep but i'd like it to run right and it seems to be loosing power as it goes up pretty badly.

im thinking fuel filter maybe... i checked fuel pressure and its right where it should be for this enine

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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 11-15-2012, 10:07 AM   #2
TJSWJ
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I have seen a few 6.0's have crank sensor issues, under load the readings go off causing the engine to miss, kinda feels like your hitting a rev limiter. Any pending codes?
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Unread 11-15-2012, 10:31 AM   #3
Ripper3494
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i had an 02 sensor code that always comes up, so i cleared it and did a few WOT runs and the problem happened each time i hit that rpm range, came back with no codes though
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 11-27-2012, 12:13 PM   #4
themonkeyman
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Are you running a VSS? I know the VSS monitors a lot more than most people realize, and ive heard of issues similar to yours being related to no VSS
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Unread 11-27-2012, 05:03 PM   #5
Ripper3494
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Quote:
Originally Posted by themonkeyman View Post
Are you running a VSS? I know the VSS monitors a lot more than most people realize, and ive heard of issues similar to yours being related to no VSS
yep i have a working VSS, when it went bad before i was amazed at how much it screwed up
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 11-27-2012, 10:07 PM   #6
rchase559
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What are you using for an intake?

I have a friend with a 5.3 in his YJ and he was having a similar issue. The motor would get to a certain RPM and then cough out until the RPM was lowered. One day out and the trail we ended up looking at it and found that the stock intake was collapsing on itself and choking the air supply to the engine. Once he altered the intake and prevented this from happening it ran just fine all the way to the rev limiter.
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Unread 11-27-2012, 10:57 PM   #7
Ripper3494
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Quote:
Originally Posted by rchase559 View Post
What are you using for an intake?

I have a friend with a 5.3 in his YJ and he was having a similar issue. The motor would get to a certain RPM and then cough out until the RPM was lowered. One day out and the trail we ended up looking at it and found that the stock intake was collapsing on itself and choking the air supply to the engine. Once he altered the intake and prevented this from happening it ran just fine all the way to the rev limiter.
im using the stock upper intake with a pvc 90 degree with a cone filter. theres no chance of it collapsing on itself that i can see
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 11-29-2012, 09:12 PM   #8
53J
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Could be valve float. Is this a fresh motor? if not how many miles on it?
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Unread 11-29-2012, 09:52 PM   #9
boarderofsnow
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I'd put this up on the 5.3L Jeep thread on Pirate. They'll have an answer for you in no time! Doing a 5.3L swap in my CJ5 and its insane how much solid knowledge is on that thread for troubleshooting LS motors. Just my $.02 Good luck!
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Unread 12-02-2012, 12:23 PM   #10
Ripper3494
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Quote:
Originally Posted by 53J View Post
Could be valve float. Is this a fresh motor? if not how many miles on it?
its got about 110000 on the clock i believe, but it used to get up there just fine, just in the last month it started having this problem
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 12-02-2012, 12:24 PM   #11
Ripper3494
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Quote:
Originally Posted by boarderofsnow View Post
I'd put this up on the 5.3L Jeep thread on Pirate. They'll have an answer for you in no time! Doing a 5.3L swap in my CJ5 and its insane how much solid knowledge is on that thread for troubleshooting LS motors. Just my $.02 Good luck!
ill take a look over there, im always too scared to post over there lol
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 12-04-2012, 04:25 PM   #12
53J
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Does it sound like valve float? or is it a dead miss?

I have heard stock used 5.3 have valve float around the 5500 area... maybe you have a spring getting weak.
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Unread 12-04-2012, 05:28 PM   #13
Ripper3494
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i'm not sure what valve float sounds like, but my engine just like stops at a certain rpm and wont go any higher and kind of sputters there. im going to try to up my fuel pressure a little since it looks like i'm a little low
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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Unread 12-07-2012, 05:21 PM   #14
jason m
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Hey Ripper I have a chance to get a 6.0 motor and me being kinda in the dark about the motors I figure I would ask you a few qeustions.

Now the motor in question is or has been in a flood. Yes I know but ive delt with this before and had good results. But those are on the older 350's and 454's anything different I should know about.

Thanks and sorry for the Highjack.

Jason.
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Unread 12-07-2012, 06:14 PM   #15
Ripper3494
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Quote:
Originally Posted by jason m View Post
Hey Ripper I have a chance to get a 6.0 motor and me being kinda in the dark about the motors I figure I would ask you a few qeustions.

Now the motor in question is or has been in a flood. Yes I know but ive delt with this before and had good results. But those are on the older 350's and 454's anything different I should know about.

Thanks and sorry for the Highjack.

Jason.
no problem. i'm by no means any sort of an expert but i know that the newer genIII engines seal much better than the older engines. if you've delt with water logged engines before i cant imagine this would be much different.

ive gotten water in my 6.0 and i did everything the same as i normally would with any other engine to get it running again

if you'd like list here's what changed from the older generation engines to the third gen engines like the 6.0

decreased rotating mass for quicker revs
decreased ring friction, yet with better oil / compression control
deeper engine skirt for increased engine rigidity for a decrease in distortion for less noise, friction, wear
six-bolt main bearing caps in lieu of two & four-bolt caps
head design increases volumetric efficiency, therefore more power at all engine speeds
quieter and more efficient valve train operation
new firing order for smoother idle and less vibration throughout the operational range
sequential fuel injection
elimination of Exhaust Gas Recirculation (most engines) by achieving a more complete burn the first time
coil-near-cylinder design; shorter plug wires for a double-hot spark
one coil per spark plug; individual cylinder timing can be tuned on the fly via the PCM and knock sensing
powerful and reliable powertrain control computer with the ability to holistically control more engine (and automatic transmission) processes than ever
throttle-by wire (most models)
all models are internally balanced without any need for balance shafts, etc.
better sealing methods at the engines covers and mating components
displacement-on-demand (DOD) that senses cruising modes and shuts down operation of cylinders for increased fuel economy (starting in some models in 2005)
same overall size as the original Small Block, offering tremendous power output for such a compact size envelope
400,000 mile longevity design
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build thread:
[url]http://www.jeepforum.com/forum/f22/94-yj-6-0-build-spud-1218315/[/url]
1994 yj stretched, locked and loaded - 6.0l vortec lq4, 4l60e, np231, Dana 44s 37" interco trxus m/t, 3.5" bds front leafs, double triangulated 4 link rear on xj front coils.
1997 ZJ limited - BONE stock
2003 tj - 4in skyjacker, 33" mickey thompsons
my on board alternator/welder write up
[url]http://www.jeepforum.com/forum/f12/alternator-welder-write-up-1301614/[/url]
my tj 1/2 doors on a yj write up
[url]http://www.jeepforum.com/forum/f12/tj-uppers-yj-half-doors-hard-top-installation-1417686/[/url]
RC vs BDS
[url]http://www.jeepforum.com/forum/f12/rough-country-vs-bds-1461555/[/url]
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