LOST JEEPS :: View topic - Serious but brief misfire?

Any idea's as to what happened?

Well drove it around for a couple hours yesterday and the problem hasn't come back. I checked for any possible leaks, nothing found just quickly going over the vehicle. I don't think it's bad gas, or low gas, tank was 3/4 full, still driving on that tank with no problems since. Still leaning towards a computer glitch. Will take it in the stealership just to see what they have to say, but I am sure this will be one of those problems that's dam near impossible to track down. I'll be happy if it just never happens again.

I've had this same problem. I actually think its 2 different problems that have been brought up in this post. First, the low fuel LIMP mode thing. My wife used to (still does) commute to work here in Southern Colorado. She had a real knack for driving home 45 miles with the low fuel light on. There was/is a very steep stretch of highway she'd climb everyday. She said she would start the hill at 75mph and she would apply more throttle and the Jeep would slowly bog down until it was only idling. After a few restarts it would give full throttle and run fine. No code, no stumble, just no power. Low fuel + 7% grade= Suckin' Air.
Now a few weeks ago we were sitting at the drive thru...waiting. As we sat, I listened...as usual. As we waited for our food, I literally heard my injection pressure change. Lost it or got to much. Something changed in my injector rattle. I've heard this before running diagnostics on other diesel trucks; vehicles will idle but the sound changes with injection pressure. As we left the drive thru the Jeep ran fine and smooth but the injectors sounded weird. The first stop sign she started missing hard, like lost 2 cylinders hard, took off and she smoothed out with more RPM's but still not right. Next stop sign, I restart it. Same thing, get it home, pull the codes...no codes. Restart and it runs fine. Did it once more the next day for just a second or two, and hasn't done it since. (1 month) Still no codes. Pretty sure it was fuel system related. Just installed Weeks' FCV Delete kit. I guess it could have been the FCV. But it sure sounded like a injection pressure issue, though one would think there would be a CEL involved. I'm guessing low pressure fuel (in this case vacuum) supply restricted, since I had 3/4 tank of fuel.

using your filter head as a bong....

Sorry for the lack of sig info. There's about 8k miles on the filter. And yes, I suspect "low-side" fuel restriction/starvation to cause this condition. If it were a "high-side" fuel issue there would have been a code or two. The 11mm lives in the back for such emergencies. Lots of options when it comes to fuel pumps for our delivery systems. May do the in-tank pump setup next. But for now the "factory" setup works most of the time. Unless you climb a steep grade with an empty tank...lol.

Yeah, I loaned the Lib to my dad about a month ago. I had the pleasure of fixing and driving his 04.5 HO Cummins 6spd for about a week. He calls me from work one morning... "Hey your check engine light came on this morning... I had to pass about 4 cars going to work, so I just stood on it; and after I passed em the light came on!!" I laughed when I saw the code...Over-boost...lol. What he doesn't know is I did a little drifting in his long box high output! Ever gone thru 6 gears sideways?? Guess that unauthorized deal works both ways! Hows the fuel aeration with the Cummins Lift Pump?? My only concern is that it may be fuel supply overkill....i.e. aerated fuel. Any one tried a air/water separator?? Like an AirDogg?

Author:	Toe [ Sun Aug 27, 2006 4:14 pm ]
Post subject:	Serious but brief misfire?
Took the CRD out to the video store last night, made a right on the main road, and as I got up to about 20mph the jeep suddenly lost power, stumbling really badly as if half the cylinders weren't firing. Came to a stop, and it was still stumbling, give it gas it would stumble worse and barely move at what would be a normal idle speed. Turned off the Jeep adn started it back up 5 seconds later, same thing a bad stumble. Turned it off and let it sit for 30 seconds, started it back up and all was good. Turned around and went back home. With how badly it was stumbling and shaking I figured something was seriously broken, but it could of been a computer issue. I had the computer flashed last week for some TSB about the battery draining, maybe this has introduced a problem. No check engine lights are on. Any idea's as to what happened?

Author:	Ranger1 [ Sun Aug 27, 2006 4:38 pm ]
Post subject:
Sounds like fuel starvation or bad fuel. If it disappears entirely, it could be computer flash issues. If it continues, especially at higher throttle, you may want to check the fuel filter drain and see how it looks. Did you fuel up recently?

Author:	Cowcatcher [ Sun Aug 27, 2006 5:41 pm ]
Post subject:
Sometimes it will throw a code without displaying the CEL. Might want to get it read to see.

Author:	valoflyby [ Sun Aug 27, 2006 7:33 pm ]
Post subject:
The only time that I had something similar happen to me was when I was really low on fuel. The chime had, well... chimed, and I took off quickly from a stop, making a hard right and heading up hill. VERY shortly thereafter I had the symptoms that you described. I was able to limp it into a parking lot, where I parked it level and primed the system. I then very carefully drove to the gas station to fuel up. If you had more than 1/8 tank.... I guess this post is irrelevant.

Author:	RFCRD [ Sun Aug 27, 2006 9:33 pm ]
Post subject:	Re: Serious but brief misfire?
Toe wrote: Any idea's as to what happened? Sounds like you are sucking air (instead of fuel) and loosing prime. Start looking for a leak in the obvious places like fuel hoses, fittings, fuel filter, H2O sensor, bleeder, etc... Did you try the primer pump?

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Author:	Toe [ Mon Aug 28, 2006 1:26 pm ]
Post subject:
Well drove it around for a couple hours yesterday and the problem hasn't come back. I checked for any possible leaks, nothing found just quickly going over the vehicle. I don't think it's bad gas, or low gas, tank was 3/4 full, still driving on that tank with no problems since. Still leaning towards a computer glitch. Will take it in the stealership just to see what they have to say, but I am sure this will be one of those problems that's dam near impossible to track down. I'll be happy if it just never happens again.

Author:	Inet_CRD [ Mon Aug 28, 2006 2:51 pm ]
Post subject:
I think there is another thread here where a few folks have had similar problems. I have had the same thing happen twice now and the problem goes away (for my CRD anyway) if you turn off the engine, wait a minute or two, then restart. The first time I had it happen I was right by a Dodge dealer, managed to limp it in, then when the tech came out to look at it mysteriously worked A - OK. No CEL but he checked for codes and found 0299, Turbo under pressure. The second time it happened I pulled off to the side of the road, turned it off and waited a minute, restarted, and the problem was gone. I didn't pay attention to the fuel gauge, but I think it was over 1/4 tank. If it happens again I'll be sure to note the fuel level. Wonder how many others are having this happen? BTW - I have ran it almost empty once or twice without the problem happening. It'd sure be interesting to be able to 'playback' the engine computer when this happens just to see what it was doing when the problem happens. Does anyone know if the ECU performs any kind of data logging?

Author:	RFCRD [ Mon Aug 28, 2006 4:40 pm ]
Post subject:
Toe wrote: Well drove it around for a couple hours yesterday and the problem hasn't come back. I checked for any possible leaks, nothing found just quickly going over the vehicle. I don't think it's bad gas, or low gas, tank was 3/4 full, still driving on that tank with no problems since. Still leaning towards a computer glitch. Will take it in the stealership just to see what they have to say, but I am sure this will be one of those problems that's dam near impossible to track down. I'll be happy if it just never happens again. One thing I have wondered about is the possibility of the air flow control valve is getting stuck partially closed causing a partial fresh air starvation and/or allowing excess EGR gasses into the engine. Shut it down and reset the computers, it goes away. Computers are basically stupid, maybe it just got confused. Would think this would throw a code.

Author:	ns_buck [ Sun Dec 14, 2014 2:46 am ]
Post subject:	Re: Serious but brief misfire?
I've had this same problem. I actually think its 2 different problems that have been brought up in this post. First, the low fuel LIMP mode thing. My wife used to (still does) commute to work here in Southern Colorado. She had a real knack for driving home 45 miles with the low fuel light on. There was/is a very steep stretch of highway she'd climb everyday. She said she would start the hill at 75mph and she would apply more throttle and the Jeep would slowly bog down until it was only idling. After a few restarts it would give full throttle and run fine. No code, no stumble, just no power. Low fuel + 7% grade= Suckin' Air. Now a few weeks ago we were sitting at the drive thru...waiting. As we sat, I listened...as usual. As we waited for our food, I literally heard my injection pressure change. Lost it or got to much. Something changed in my injector rattle. I've heard this before running diagnostics on other diesel trucks; vehicles will idle but the sound changes with injection pressure. As we left the drive thru the Jeep ran fine and smooth but the injectors sounded weird. The first stop sign she started missing hard, like lost 2 cylinders hard, took off and she smoothed out with more RPM's but still not right. Next stop sign, I restart it. Same thing, get it home, pull the codes...no codes. Restart and it runs fine. Did it once more the next day for just a second or two, and hasn't done it since. (1 month) Still no codes. Pretty sure it was fuel system related. Just installed Weeks' FCV Delete kit. I guess it could have been the FCV. But it sure sounded like a injection pressure issue, though one would think there would be a CEL involved. I'm guessing low pressure fuel (in this case vacuum) supply restricted, since I had 3/4 tank of fuel.

Author:	gmctd [ Sun Dec 14, 2014 12:04 pm ]
Post subject:	Re: Serious but brief misfire?
ns_buck wrote: I've had this same problem. I actually think its 2 different problems that have been brought up in this post. First, the low fuel LIMP mode thing. My wife used to (still does) commute to work here in Southern Colorado. She had a real knack for driving home 45 miles with the low fuel light on. There was/is a very steep stretch of highway she'd climb everyday. She said she would start the hill at 75mph and she would apply more throttle and the Jeep would slowly bog down until it was only idling. After a few restarts it would give full throttle and run fine. No code, no stumble, just no power. Low fuel + 7% grade= Suckin' Air. Now a few weeks ago we were sitting at the drive thru...waiting. As we sat, I listened...as usual. As we waited for our food, I literally heard my injection pressure change. Lost it or got to much. Something changed in my injector rattle. I've heard this before running diagnostics on other diesel trucks; vehicles will idle but the sound changes with injection pressure. As we left the drive thru the Jeep ran fine and smooth but the injectors sounded weird. The first stop sign she started missing hard, like lost 2 cylinders hard, took off and she smoothed out with more RPM's but still not right. Next stop sign, I restart it. Same thing, get it home, pull the codes...no codes. Restart and it runs fine. Did it once more the next day for just a second or two, and hasn't done it since. (1 month) Still no codes. Pretty sure it was fuel system related. Just installed Weeks' FCV Delete kit. I guess it could have been the FCV. But it sure sounded like a injection pressure issue, though one would think there would be a CEL involved. I'm guessing low pressure fuel (in this case vacuum) supply restricted, since I had 3/4 tank of fuel. Read thru the Noob guide, paying close attention to filter, lift pump, and air leakage in the fuel system - when you replace the filter head, you must also drop the fuel tank to replace the plastic connectors with rubber fuel hose and clamps, as that is a major source of air leakage - click on the link to view viewtopic.php?f=5&t=54207

Author:	ns_buck [ Sun Dec 14, 2014 1:11 pm ]
Post subject:	Re: Serious but brief misfire?
I read the noob guide many times, long time ago. Even before I bought the CRD. Used to be that GUY at the stealership. Cummins Tech, CRD Tech, Powerchoke Tech, etc... I have the updated fuel filter head, all the quick disconnect fittings removed. Used to have an inline fuel pump too. It died and got removed. Back to vacuum supply for now. I think my wife's problem was air intrusion at the pick-up in the tank. The misfire I experienced seemed like a random or multiple cylinder misfire... Guess its possible that it could have been "air in the lines"... I can't type that with a straight face...lmao. Isn't that always the easiest answer?? Must have air in the fuel!!! Idk, I once replaced a pressure limiting valve on a 05 CRD. Acted just like air in the fuel....lol. Except for the rail pressure code it kept throwing. Could be air, restriction, inj. pump, rail pressure sensor, limiting valve, injector(s), some injection gnome using your filter head as a bong, list is pretty much endless....

Author:	gmctd [ Sun Dec 14, 2014 4:34 pm ]
Post subject:	Re: Serious but brief misfire?
Good, but your sig gives no hint of any previous forum-derived upgrades - not sure which 'vacuum supply' you're referring to, but it has nothing to do with any fuel-delivery system in the KJ - however, as the KJ fuel delivery system is 'draw' type, where fuel is pulled from the tank thru the filter head to the lift-pump on the rear of the CP3 Inj Pump, some have referred to it as vacuum-type system - but, since the GM 6.5 shuttle-type lift pump satisfies 'flow-thru-when-failed' requirement with correct flo-rate and pressure, as does the DCJ\CARTER in-tank LP module for the CUMMINS ,next step would be to install an auxiliary lift pump, either in-tank, or the external GM unit If you are\were DCJ service, then you will know any BOSCH CRD fuel injection fault will give DTC, unlike the fuel-delivery side, with only water-in-fuel and Fuel Temperature Sensor deviation - could be ruptured corrugated tubing in the fuel-pickup module, where above 3/4-tank would be ok, below 3/4-fuel exposes the rip - be very unusual, but not impossible Your posted symptoms hint of fuel supply starvation - you'll need to prove the fuel-pickup scenario, which will involve dropping the tank - I'd take that opportunity to install the DCJ in-tank LP, or at least try a 'nuther lift pump with a low-pressure gage on the outlet-side and a vacuum gage on the inlet side - you'll soon know if it's blockage or leakage

Author:	rancherman [ Sun Dec 14, 2014 4:40 pm ]
Post subject:	Re: Serious but brief misfire?
ns_buck wrote: using your filter head as a bong.... Now THERE'S an example of repurposing/recycling! seriously now; eliminate the obvious possibilities first. How many miles on the fuel filter? The sudden change in your perceived fuel rail pressure sound may indeed been just that! Isn't it cool how a drivethru makes the perfect sounding board?!? A little foam would certainly affect it, and soon be only 'running on 2' (or less) lol Keep a little wrench on hand to immediately pop the bleeder next time it acts up. and 'see' whatcha got..

Author:	ns_buck [ Mon Dec 15, 2014 12:43 am ]
Post subject:	Re: Serious but brief misfire?
Sorry for the lack of sig info. There's about 8k miles on the filter. And yes, I suspect "low-side" fuel restriction/starvation to cause this condition. If it were a "high-side" fuel issue there would have been a code or two. The 11mm lives in the back for such emergencies. Lots of options when it comes to fuel pumps for our delivery systems. May do the in-tank pump setup next. But for now the "factory" setup works most of the time. Unless you climb a steep grade with an empty tank...lol.

Author:	rancherman [ Mon Dec 15, 2014 11:28 am ]
Post subject:	Re: Serious but brief misfire?
[/quote] - also installed the Cummins Filter-minder in the air box - indicates dirty air filter, plus any unauthorized non-sanctioned full-throttle acceleration events, if you can ascertain my meaning, eh.....................[/quote] 'unauthorized full throttle" ... ie; you have kids too that drive your lib? I flew my son to New Braunfels Tx. to pickup my Lib, and drive it home... From New Braunfels to just north of Ft. Worth, he said it was Banzai type driving conditions! (yah, sure it was!!!)

Author:	gmctd [ Mon Dec 15, 2014 1:01 pm ]
Post subject:	Re: Serious but brief misfire?
No fuel aeration - the fuel manager is pressurized by the Carter in-tank lift pump, just like on the big Rams - the fuel-air separator in the CP3 takes care of any small amount that gets thru, dumping it back into the tank to exit next time the fuel cap is removed - Those big 200gph Air Dogs and such, designed for 15 liter 18-wheeler systems, really aerate the fuel by continuously dumping 170gph back into the tank, not to mention pressurizing the tank - FYI: My big 3500 Cummins Ram returns ~24-26mpg at 50mph If I drive 50mph for one hour, fuel consumed at 25mpg in 50 miles is 2gal Fuel consumed per hour is therefore 2gph - 10mpg would be only 5gph What is the thinking behind the universal Dodge forum claims that my truck needs a $700 200gph fuel lift pump system, or it will never ever run right again? 200gph at 50mph = insanity $700 = dementia To wit: a 15psi 15-35gph lift pump is more than suitable for my big Cummins, and for the smaller KJ 2.8L, being half the 5.9L displacement of the Cummins Bigger ain't always better Also, the KJ, and most Diesels, fuel cap is vented for +/- 1psi, 2"hg - it is very important for Diesel fuel systems to vent excessive pressure as well as excessive vacuum because of aeration, those tiny bubbles you see (and many you can't see) in Diesel fuel - we want some vacuum in the tank to reduce surface tension on the fuel, allowing the below-surface aeration to coalesce and emerge from the fuel - IIRC, API states that ~75% of all Diesel fuel is aerated, bad for pumped injection systems - too much vacuum reduces efficiency of the lift-pump - so, 2"HG, or -1psi, vacuum is required - outside BARO is 15psi, in-tank is (15psi - 1psi) = 14psi, or 2"hg vacuum Those big 200gph systems tend to keep the fuel tank under pressure - as do any lift pumps over 35gph - very conducive for aeration

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Author:	gmctd [ Mon Dec 15, 2014 7:49 am ]
Post subject:	Re: Serious but brief misfire?
ns_buck wrote: Sorry for the lack of sig info. There's about 8k miles on the filter. And yes, I suspect "low-side" fuel restriction/starvation to cause this condition. If it were a "high-side" fuel issue there would have been a code or two. The 11mm lives in the back for such emergencies. Lots of options when it comes to fuel pumps for our delivery systems. May do the in-tank pump setup next. But for now the "factory" setup works most of the time. Unless you climb a steep grade with an empty tank...lol. I would type 'no problemo', but reading thru your posts, it appears as tho the problemo is escalating from 'on grades-low fuel' to flat-lander in drive-thru - might behoove you to up-schedule your planned maintenance, after verifying the fuel filter isn't dirtier than it should be, sooner than it should be - too bad DCJ didn't spec the combo WIF\vacuum switch to indicate plugged filter, like GM did with the 6.5L fuel delivery system FYI, the DCJ Cummins\Carter in-tank LP cured the fuel problems in my KJ, and up-graded to the Cummins\Fleet-guard fuel manager while I was at it - a little more bulky, but did not need the manual primer, and is a top-loader - plus, can visually inspect the drop-in filter element for dirtier than should be, sooner than should be - also installed the Cummins Filter-minder in the air box - indicates dirty air filter, plus any unauthorized non-sanctioned full-throttle acceleration events, if you can ascertain my meaning, eh.....................

Author:	ns_buck [ Mon Dec 15, 2014 11:50 am ]
Post subject:	Re: Serious but brief misfire?
Yeah, I loaned the Lib to my dad about a month ago. I had the pleasure of fixing and driving his 04.5 HO Cummins 6spd for about a week. He calls me from work one morning... "Hey your check engine light came on this morning... I had to pass about 4 cars going to work, so I just stood on it; and after I passed em the light came on!!" I laughed when I saw the code...Over-boost...lol. What he doesn't know is I did a little drifting in his long box high output! Ever gone thru 6 gears sideways?? Guess that unauthorized deal works both ways! Hows the fuel aeration with the Cummins Lift Pump?? My only concern is that it may be fuel supply overkill....i.e. aerated fuel. Any one tried a air/water separator?? Like an AirDogg?

Author:	rancherman [ Mon Dec 15, 2014 1:11 pm ]
Post subject:	Re: Serious but brief misfire?
ns_buck wrote: Yeah, I loaned the Lib to my dad about a month ago. I had the pleasure of fixing and driving his 04.5 HO Cummins 6spd for about a week. He calls me from work one morning... "Hey your check engine light came on this morning... I had to pass about 4 cars going to work, so I just stood on it; and after I passed em the light came on!!" I laughed when I saw the code...Over-boost...lol. What he doesn't know is I did a little drifting in his long box high output! Ever gone thru 6 gears sideways?? Guess that unauthorized deal works both ways! Hows the fuel aeration with the Cummins Lift Pump?? My only concern is that it may be fuel supply overkill....i.e. aerated fuel. Any one tried a air/water separator?? Like an AirDogg? well, the aeration problems on the Rams is usually caused BY the airdog, fass.. but they also 'cure' it too. There are now tons more 'return' back to tank, which whips up the contents. When the tank is lower than, oh say 1/4, foamy supply is whatcha get. This is where the airdog or fass shines; they do a good job at fixing the problem they've created. You probably noticed when you fill it with fuel, how easy diesel foams?? Our jeeps suffer from poor fuel line engineering, and the aeration is from 'leaks'. Unfortunately Both kinds of aeration end up causing the same type problems.

Author:	ns_buck [ Mon Dec 15, 2014 3:03 pm ]
Post subject:	Re: Serious but brief misfire?
Thanks for the input guys. I like the idea of air separation and I think the Cummins/Carter pump is a little overkill for the application. I might go back to an inline. 4-7psi seemed to work just fine and even when the cheap p.o.s. died it it didn't cause a restriction due to its flow-thru design. The dumb thing is it didn't die... Had the wires pulled too tight and they broke where they enter the pump. How much does a Cummins/Carter setup run??