Hi members,

My 05 CRD suddenly developed a cycling engine surge at idle. It races up and down a few RPMs, not noticeable at the tach, just a slight movement of the needle, if you look at it very carefully, at more or less one second intervals. It is more noticeable in Drive, Jeep not running, and almost gone on Neutral or Park. There are no codes, nor CEL, on the dashboard. The injectors appear to be working correctly, audible symmetrical pulses evenly for the four of them, no loose connections to any of the sensors, no leaks that I could visually check. I have not notice any changes in the performance, either in city driving nor on the highway, up to 50 MPH. No exhaust smoke either. The only item that I have not notice before is visible white(blue) smoke up from the oil fill cap (cap off) mixed with the crankcase venting.

I had the oil changed day before yesterday and the symptoms disappeared for the rest of the day, but yesterday they were back. Also, last Sunday, coming back from the Outer banks in NC, I stopped for a refuel on VA near US 17 and the diesel fuel pump was label #2 diesel. I put about 16 gallons and drove the rest of the way back to home without noticing any thing out of order. Just in case, I had my mud tires on and Monday was raining and the wheels started to loose traction so I setup the 4 wheel fulltime at the transfer case to drive safety. I have my four seasons tires back again.

I am scheduled to start a long (5,000 miles +/- ) trip tomorrow and would like to have a peace of mind with the jeep.

Any ideas?

Thanks in advance.

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Sergio05CRD

Is the AC on when you are noticing the idle surge?
That would be the most likely culprit.

The voltage regulator in the alternator is another possibility.

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U.S. Army Retired

Thanks flash7210,

The A/C was off, actually the air handling system for the cabin was off.

I have not checked the voltage regulator, and is a good candidate as it is the factory alternator (12 years, 196,780 miles)

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Sergio05CRD

When I replaced my voltage regulator, I was not able to diagnose it with voltage tests.
The symptoms included intermittent flickering headlights.
So I took a chance and replaced the regulator and all was fixed.

Also, a bad alternator pulley can also cause problems.

_________________
U.S. Army Retired

I did a voltage test and checked OK keep 14.34 volts at idle fluctuating between 14.33 and 14.34 volts at the rate of 2 to 3 seconds.
How do you replace the voltage regulator? It is not an integral part of the alternator? I have not driven at night, so I do not know if I have flickering headlights.

I have a new alternator pulley installed July 2016, it is sealed and filled with oil. the outside diameter is about 1/64 " smaller that the original, but in my book that is OK because it just increase the rpm's of the alternator slightly. It does not show any sign of leakage and or vibration. The accessory belt runs smoothly.

Well, started to rain here and my driveway mechanics have stopped. I will keep a vigilant eye during the trip and see what happens.

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Sergio05CRD

my 05 is doing the same thing, but in addition sometimes when I start it runs extremely rough and stalls. It otherwise seems fine, not down on power at all. I'm planning to take it to my mechanic in the next week or 2 ( I only drive it on weekends) ill let you know what he finds. Its winter here , so not using AC and my headlights aren't flickering at all.

Check wiring at temperature sensor (behind the thermostat). Check temperature sensor too.

Unplug it and see if the problem gets worse. If it does get worse then you know it's not that sensor and if doesn't get worse than most likely it is that sensor.

The sensor on the side of the airbox is also notoriously sensitive to being bumped or even unplugged. Maybe a wire cracked or the plug is just not seated properly.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

Thank you all,
I added Marvel Miracle Oil to the fuel tank at the rate of 4 oz per 10 gallons at the beginning of the trip, and by my first stop about three hours latter at interstate speed the engine surge had disappeared. I continue the use of the additive for the rest of the 5,400 miles and no signs of the problem. Back home now and even though i do not know the cause, I am glad that is not there any more.

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Sergio05CRD

MMO is good stuff! I add a few ounces to fuel at every fillup and engine oil on every oil change!
Helps keep everything nice and lubricated...

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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

What is it? The more I hear people on hear talking about it the more I wanna try it because it seems to solve everything.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

While it will not solve everything; (man I wish it would), it will add some very valuable additional lubricity to both the oil and fuel!
I mix a few ounces of MMO along with about 3/4 Qt. of cheap Walmart 2 cycle motor oil and then add a few ounces of Diesel Kleen + Cetane Boost to top off the mix and add it to the fuel tank at every fill up. Been doing this for several years now! This mix keeps the CP3 and injectors well lubricated as today's low sulfur fuel lubricity properties is extremely poor. And we all know what the price of a new CP3 or injectors run!!!

As to the engine oil, I add a few ounces of MMO to the engine oil at every oil change and I can attest as others on LOST have proclaimed, the engine does seem to idle more smoothly with slightly less audible noise.....

I also add these same additives to my Dodge Cummins in higher proportions due to the larger oil and fuel capacities....

Kinda sold on them until someone can convince me otherwise!

But I never fault anyone if they do not agree, to each his own, it's your vehicle!
I would suggest before anyone starts throwing stones at the above items, try it, judge for yourself and draw your own conclusions....

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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

I have not used MMO in the diesel fuel until this time, I have used other additives and cetane boosters on several occasions in the past, but i did used it frequently in my '62 TR-3 and my '69 TR-6 when the lead was removed from the gasoline. That is, until I got hard valve seats and new type valve valve guides installed on them. They still run with the original engine. Not that often since I got my CRD and started going in offroad trips. MMO works, did work from me then, and did work for my now.

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Sergio05CRD