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Unread 06-04-2014, 08:12 AM   #1
outofrng623
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I have gotten a lot of help from a lot of people on here in my original thread (http://www.jeepforum.com/forum/f310/...-help-1490914/), but I still have the issue. I wanted to start a new thread as my original one has 26 pages going...and I want to get something cleaner going with some compiled info. Any help is greatly appreciated. So here is my breakdown. 2004 JGC 8cyl 4.7 NON ho Symptoms; Getting anywhere from 6mpg (winter blend) to 10mpg around town, around 18 highway...When I first got the Jeep 2+ years ago, I was getting 13 around town. Easy 20 highway. All calculated by hand, no EVIC. About 4 months later the issue started. Rough idle, will surge/slight stumble (not a lot) when idle from time to time. Maybe once every 3-4 weeks the Jeep will stumble and stall or just shut off completely. Starts right back up. Starting the Jeep takes about 4 seconds, cranks about 4 times before it starts. Mode 6 fails, TID 11, 31 both o2 half cycle counts and 51 purge monitor IAC shift, sometimes 52 purge monitor adaptive fuel shift, 53 purge monitor rpm shift, 61 & 62 both leak detection pump period. I was told my purge solenoid is overactive, but no one can tell me why. I have a constant air intake type "whistle", throttle position sensor shows 10.6 -11% key on and same when idle. Slight exhaust/gas smell at startup Downstream o2s look lazy from time to time. I get some clunky transmission action here and there. Like a weird downshift or upshift when around the shift points, around town. Not highway. NO CEL or stored codes.
Add to the list a hard start. Went to start, few seconds and it didn't catch, waited a few seconds went to start and it wouldn't catch. Third time it started but sounded like it was lacking fuel

What has been done since the issue started Cruise control works no problem. All 8 plugs, champion copper Air filter TB cleaning, took it off, cleaned it, cleaned what I could reach in intake. Seafoam through the TB, blew out a lot of black, now if I seafoam exhaust comes out clean. All 8 coils Fuel pump, mopar Fuel pressure is correct and holds Thermostat Map sensor is working properly TPS Mopar IAC Mopar All 4 o2's Mopars downstream, last year, Mopar upstream last month. Exhaust manifold gasket to fix leak New cats and exhaust high flow 3" I've checked grounds in engine compartment, all reading within 1/2v of the battery. Jiggled all harnesses, no change. Pulled PCM connectors, appeared fine, reattached Coolant system was pressure tested. Banged the pcm thinking maybe there was a short or something, no change. I've heard of pcms needing a reflash for o2 and driving issues, but only found a tsb on 4.0 I have disconnected the battery for x amount of time to reset after most changes. Sprayed every line I could find with TB cleaner, no RPM shifts. That's all I can think of at the moment. Thanks in advance Also upgraded 136a alternator to a 160amp. My stereos pushing 1k+ watts so I figured it would do some good.

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Unread 06-09-2014, 09:06 AM   #2
ChrisHager
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Wow. You've covered quite a bit. I find it strange that you have such a large range - 6 mpg in town and up to 18 mpg on highway. The odd shifts, stalling, and rough starts can be caused by a bad CKS. I believe if the CKS is on its way out, it can sometimes cause these problems without throwing codes. Just a thought after my first read through. I'll think about this one for a little while and see if anything else comes to mind.
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But ChrisHager makes me want to poor water on a burning bucket of gasoline now just out of curiosity.
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The latest lift kit from Rough Country? :D
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Your symptoms sounds just like what it does when it's not doing what it should because of how it is.
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Unread 06-09-2014, 09:22 AM   #3
outofrng623
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Cks the same as cps? Also Wow. Thanks for looking. 6 was winter blend gas. Now I get around 9. Lmao. I've had 20 straight highway cruising at 70+. My issues could've been multi faceted and hitting a little at a time. My bank 1 ltft is higher than the 2 and a 2500rpm rev does bring it level so maybe a small vac leak.
There is a reward for the solution but throwing parts takes away from the reward money. Lmao.
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Unread 06-09-2014, 09:36 AM   #4
ChrisHager
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CKS is Crankshaft Position Sensor whereas CPS is Camshaft Position Sensor. I agree in that throwing parts at something isn't the right way to go. To bad you don't have an obvious code...
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But ChrisHager makes me want to poor water on a burning bucket of gasoline now just out of curiosity.
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Originally Posted by billzcat1 View Post
The latest lift kit from Rough Country? :D
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Originally Posted by Jeeples View Post
Your symptoms sounds just like what it does when it's not doing what it should because of how it is.
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Unread 06-09-2014, 09:49 AM   #5
outofrng623
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Such is the way with jees, no? Lol. Only obvious code I've had is a 0420 after doing the exhaust, that was remedied by changing the upstreams to new mopars. I have a boat load of mode 6 and real time date, but no actual cel.
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Unread 06-09-2014, 10:05 AM   #6
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Correct me if I'm wrong, but the computers on these Jeeps will correct the air/fuel ratio for almost all issues. For example, if you've got a slightly clogged fuel filter or something like that. So there are very few items that will actually create a low MPG condition. O2 sensors are one, perhaps MAF sensor. But I mean, there really isn't a lot that's going to cause that to happen engine-wise unless the engine is just running like absolute garbage.

I'd be looking at fuel quality, brakes (dragging can lower MPGs), or other external factors.
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Unread 06-09-2014, 12:30 PM   #7
outofrng623
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I jinxed myself. After weeks of driving...the same trips that would throw the p0420 everytime...and not having an issue since the new o2s...it threw the code today. It looks like I have quite the left bank issue. I throw the 420 which is inefficient car bank 1, my LTFTs are whacky on that side...
Not a happy camper today. At all. No bueno
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Unread 06-09-2014, 12:47 PM   #8
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And now it's running worse. Not horrible. Just worse. Much more shaking and ups and downs but not noticeable on the tach. Feels like a miss but not as steady. One guy told me running rough is usually an air issue and the hiccups are electrical. Around every 5 seconds or do I'll get a wee bit of a rumble. Feels like some leaned against the car, little shimmy. Lol
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Unread 06-09-2014, 04:29 PM   #9
miami5th
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When I had a big drop in my MPG it was due to a stuck caliper piston, constantly applying brake pad pressure to the rear passenger wheel.
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Unread 06-09-2014, 04:35 PM   #10
outofrng623
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Today. With the way things have been...maybe I'll pull off my brakes and see if it helps. ( ; it is a valid point though, but we've looked and my vehicle will roll at idle without issue. Runs like pooh though.
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Unread 06-09-2014, 07:36 PM   #11
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Try disconnecting the top hose on your purge solenoid, or disconnect it at the TB like I have mine. I have the "overactive PS" issue. Cover the hose or TB inlet so nothing gets sucked down there.
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Unread 06-10-2014, 03:41 AM   #12
outofrng623
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Try disconnecting the top hose on your purge solenoid, or disconnect it at the TB like I have mine. I have the "overactive PS" issue. Cover the hose or TB inlet so nothing gets sucked down there.
I believe it throws a code when that's done, but what is the purpose? What prompted you to do that and what were the results? Did you ever research to see what causes it or are you still driving around like that?
Thanks
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Unread 06-10-2014, 06:31 AM   #13
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Quote:
Originally Posted by outofrng623 View Post
I believe it throws a code when that's done, but what is the purpose? What prompted you to do that and what were the results? Did you ever research to see what causes it or are you still driving around like that?
Thanks
Originally I did get a p0443 code that said the purge solenoid was bad. After replacing the solenoid three different times, I tried the electrical connection, checked all the hoses for cracks, replaced the vapor canister, checked every ground I could find, replaced the Iac only because I cleaned it just before this problem came up. Now I have a piece of cloth zip tied over the tb inlet and a check engine light on. The point being it runs until some one comes up with another idea. It's worth a shot.
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Unread 06-10-2014, 06:38 AM   #14
outofrng623
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Did you notice any operating changes? So the tube is just venting into the eng compartment versus into the tb?
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Unread 06-10-2014, 07:05 AM   #15
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Did you notice any operating changes? So the tube is just venting into the eng compartment versus into the tb?
I haven't noticed any changes directly related to disconnecting the hose. And yes it is venting into the engine bay.
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