Engine shuddering and unresponsive to throttle input

SBosco · **Posted:** Tue Jul 22, 2008 8:11 am

I was driving to work this morning at about 20 mph or so and suddenly the engine dropped to idle and started shuddering severely and erratically.

I tried feathering the throttle a bit but there was no response.

Tried shifting into neutral, same thing.

I then pulled over, and took a peek under the hood. Everything seemed to be in order so I figured maybe it was an air in fuel line issue.

I gave the system a number of pumps from the fuel primer (while still idling and shaking erratically). No difference.

Then I got back into the Jeep and turned it off. Started back up and it immediately continued to shudder, and still failed to respond to throttle input. So I shut it off again.

On the second restart, it ran perfectly and didn't miss a beat the rest of the 20 minute ride to work.

Any ideas?
Anything like this happen to anybody else?
All input would be greatly appreciated. Thanks.

dieseldawg · **Posted:** Tue Jul 22, 2008 9:12 am

I had the same thing happen. Exactly as you described it. I was leaving for a camping trip with a 1000 lb trailer behind the CRD. I think it took 3 restarts for mine to go away, but then ran fine for the 1.5 hour drive to the campsite, not issues at all. It hasn't done it again since. Mine happened back in early April. I wondered if it was water in the fuel that got through some how. Just a rough WAG though. I'd be curious to hear if anyone else has had this happen. I have the Cummins fuel pump and my fuel pressure gauge was showing the normal 9 psi during this event, so I don't think it had anything to do with fuel quantity, maybe just quality.

Craig

SBosco · **Posted:** Tue Jul 22, 2008 9:27 am

What I don't understand is why the engine immediately returned to normal after several restarts. If it was a fuel quality problem, wouldn't it be more progressive? Not to mention, the engine should have responded to throttle input...bad fuel aside, more fuel=more combustion. Unless the ECU/PCM sensed the bad fuel and sent the Jeeps into limp mode.

Hmm, I hate blaming it on gremlins, but it seems as though there may be no logical explaination?

ATXKJ · **Posted:** Tue Jul 22, 2008 9:32 am

If you do a search on Limp mode - you'll get a lot of information, but no conclusive answers - I think it's a fuel problem and It would be interesting if anyone has had that after they installed a lift pump.

SBosco · **Posted:** Tue Jul 22, 2008 9:44 am

dieseldawg has the cummins lift pump and it happened to him as well.

ATXKJ · **Posted:** Tue Jul 22, 2008 10:08 am

I missed that - although it tends to eliminate the most common theory of air in the fuel.
(mine occured after a bad batch of fuel so water in fuel would still be consistent)

SBosco · **Posted:** Tue Jul 22, 2008 10:33 am

Could it have been a clogged injector? That would make sense with regard to the shuddering...one cylinder was not igniting and the engine was therefore imbalanced. Maybe the depressurizing and repressurizing of the fuel rail/system on shutdown and restarts dislodged the clog?

That's my best guess so far.

dieseldawg · **Posted:** Tue Jul 22, 2008 10:52 am

It seems like a clogged injector could have been it. I am also running the CAT2 filter setup. So I am missing a "true" water separator. You would think that an engine even if it lost an injector would still be able to rev some. When it was happening to me, I could put the pedal to the floor and no change in RPM and the shuddering would continue. This problem started as I took off, but then the restarts and what not were all while pulled over on the side of the road. I just chocked it up to a brain fart and continued on. Water was my only guess, but seems like I would have had more problems later if water was the issue.

Craig

Bill.Barg · **Posted:** Tue Jul 22, 2008 11:13 am

SBosco wrote:

dieseldawg has the cummins lift pump and it happened to him as well.

It looks like his shudder problem happened befor he installed the pump?

SBosco · **Posted:** Tue Jul 22, 2008 11:15 am

I still have the stock filter setup, and I had the same exact result with the full throttle application and no change in rpms. Yes it is possible for an engine to run and rev without the operation of one cylinder.

My mother has a restored 1974 Chevy Nova and, with the old engine, it was running on 6 of the 8 cylinders. We occaisionally drove it around like that for months before the engine swap.

Anyway, my point is that while it is technically possible for the engine to run and rev while not firing on all cylinders, the ECU/PCM may not let it. It seems like a logical safety feature because as the revs increase, so does the potential for permament damage.

SBosco · **Posted:** Tue Jul 22, 2008 11:19 am

Bill.Barg wrote:

SBosco wrote:

dieseldawg has the cummins lift pump and it happened to him as well.

It looks like his shudder problem happened befor he installed the pump?

I considered that until I read more carefully:

dieseldawg wrote:

I had the same thing happen. Exactly as you described it. I was leaving for a camping trip with a 1000 lb trailer behind the CRD. I think it took 3 restarts for mine to go away, but then ran fine for the 1.5 hour drive to the campsite, not issues at all. It hasn't done it again since. Mine happened back in early April. I wondered if it was water in the fuel that got through some how. Just a rough WAG though. I'd be curious to hear if anyone else has had this happen. I have the Cummins fuel pump and my fuel pressure gauge was showing the normal 9 psi during this event, so I don't think it had anything to do with fuel quantity, maybe just quality.

Craig

Bill.Barg · **Posted:** Tue Jul 22, 2008 11:29 am

Sbosco is right. Hmm,

dieseldawg · **Posted:** Mon Jul 28, 2008 9:09 am

Well guys,

It happened again. I was sitting at the yield sign on a fairly steep hill in PA, and when it was clear for me to go, hit the pedal, and it took off slightly, then went into the stutter mode. This time I did have a little throttle response so I continued to drive it. I'm beginning to think that it was missing on one cylinder. During this driving though, no excessive smoke out the tail pipe or anything other than just the feeling of a miss. I had full fuel pressure from my lift pump and no other instrument lights on. I drove for about two miles and found a parking lot. Shut it off for 10 seconds, restarted, and it has been running fine ever since. Odd part now, both times it has happened, I was on a grade. First time was facing downhill, this time facing up hill. Do we have any sensors for roll over that might be tripping or anything like that? This also rules out my idea of water in the fuel that I had last time, because the water would have worked its way out after two miles of driving. I think the computer makes some weird adjustment on the fuel timing that throws it off and until the restart, the problem doesn't go away. Just a rough wag though.

Thanks for listening,
Craig

SBosco · **Posted:** Wed Jul 30, 2008 8:58 am

Fuel timing seems like a plausible cause as well. It might be difficult to determine what is causing it though.

gmctd · **Posted:** Wed Jul 30, 2008 12:15 pm

Altho I only drive the mule for testing\proving purposes, the only thing I've seen similar is that I automatically assume the auto configuration while driving the mule: lf on brake, rf on go (don't work so good in the big 6sp manual trans Ram, don't you know!) - several occasions on go the mule stumbles, go pedal becomes dead\insensitive (takes a lotta pedal to get any action), very scary WTF????? - turns out it's due to lf not totally releasing brake while go is demanded - placing lf firmly on floorboard restores go

That's my story, and I'm stickin' to it...............................

Oddly enuff, you guys got '06's, with 4wd ABS Traction Control, which the '05's got none of.

danoid · **Posted:** Thu Jul 31, 2008 1:37 pm

dieseldawg wrote:

Odd part now, both times it has happened, I was on a grade. First time was facing downhill, this time facing up hill. Do we have any sensors for roll over that might be tripping or anything like that?

I don't think so, 'course I have an 05 without ESP.

It happened to me once, pulling out of a parking lot onto a street. All flat, no grade, wasn't even driving more than 5-10 mph. I have done no modifications to my fuel system other than electrically disabling the heater (and I've never had any known leaks or issues). Happened in October of 06 and never since.

SBosco · **Posted:** Thu Jul 31, 2008 1:49 pm

I have an '06 and was on a relatively flat road when it happened.

The common thread seems to be the occurance of the condition when throttling up from idle.

msilbernagel · **Posted:** Thu Jul 31, 2008 3:36 pm

I've had it happen a couple of times in the past (model year 05), but haven't seen it since the filter was changed (back then). Since, I've added the pump-enabled sending unit so it's under positive pressure.

I wonder if the air-in-system gets the CP3 cavitating under certain conditions -- and a restart is necessary to clear it, or if the ECM just gets confused. It's happened to so many, although infrequently, and the circumstances are fairly similar.

Mark
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SBosco wrote:

I have an '06 and was on a relatively flat road when it happened.

The common thread seems to be the occurance of the condition when throttling up from idle.

Topan · **Posted:** Fri Aug 29, 2008 2:54 am

msilbernagel wrote:

I've had it happen a couple of times in the past (model year 05), but haven't seen it since the filter was changed (back then). Since, I've added the pump-enabled sending unit so it's under positive pressure.

I wonder if the air-in-system gets the CP3 cavitating under certain conditions -- and a restart is necessary to clear it, or if the ECM just gets confused. It's happened to so many, although infrequently, and the circumstances are fairly similar.

Mark
-

SBosco wrote:

I have an '06 and was on a relatively flat road when it happened.

The common thread seems to be the occurance of the condition when throttling up from idle.

Hi Mark,
What filter did you go for? The OEM?
Because this bug just happened to me twice in 2 weeks....start getting annoying.
I also have a 2005, allthough European, so i am hoping your setting could solve my problem.

Thanks
Blaise

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

If this were some kind of limp mode, why no code? If the engine is noticing anything funny and trying to react to it-- it should set a trouble code. Every person who as had this has not had a code. I have not had anything like this since the lift pump install, but have had it before. Always no code.

Engine shuddering and unresponsive to throttle input

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