Hey yall,

I posted one of my KJ woes in this thread here: viewtopic.php?f=5&t=74930&p=785708#p785708

But I haven't figured out the fix for it yet, and have had only one response thus far as well, so I began searching the internet for "Engine Surging" problems and found a few interesting reads. I'm worried that unplugging my MAF is what is causing my engine-surge issues at stops, but I'm not sure since so many people say to simply unplug the MAF to engage ORM (without repercussions of engine surging).

Check out these articles and let me know what you think: http://www.autoserviceprofessional.com/ ... rge?Page=5
"Funky MAF

A malfunctioning MAF sensor can cause a wild up/down engine idle speed (say, 0-2,000 rpm). This might be caused by a loose harness connection or by a damaged or contaminated sensing wire.

The MAF sensor measures the amount of air flowing through the throttle valve. The ECM uses this information to determine fuel injection time and to provide the necessary air-fuel ratio. Inside the MAF meter is a heated platinum wire which is exposed to the flow of intake air. By applying a specific current to the wire, the ECM maintains a specific reference temperature at the wire. The incoming air cools the wire (and an internal thermistor), affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the MAF. This voltage level is proportional to the airflow through the sensor. As a result, the ECM uses this to calculate the intake air volume.

The circuit is constructed so that the platinum hot wire and the temperature sensor provide a bridge circuit. The power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined wire temperature.

If there is a defect in the sensor (or an open or short in the MAF circuit), the voltage level deviates from the normal operating range. The ECM interprets this as a malfunction in the MAF meter and sets the DTC.

P0101: This indicates high voltage (engine speed less than 2,000 rpm, coolant temperature 158 degrees F or higher and voltage output of the MAF is more than 2.2V); or low voltage (engine speed is more than 3,000 rpm and MAF voltage output is less than 0.93 V).

P0102: MAF circuit low input (less than 0.2 V). Detection is based on an open in the MAF circuit for three seconds or more. The MAF may be faulty or simply disconnected or the MAF may be dirty/contaminated (NOTE: If the engine is equipped with an aftermarket “oiled” air filter, it is possible that an over-oiled filter may be causing this).

P0103: MAF circuit high input (more than 4.9 V). This usually indicates a short in the meter circuit. The MAF may be disconnected or damaged.

P0104: The MAF circuit is incomplete (poor connection, wiring broken or frayed or poor connector connection. This might also indicate an intake air leak.

Diesel surge

Diesel engines (we’ll cite Ford’s 7.3L, 6.0L, etc., as examples) typically feature a dedicated high-pressure oil system that operates the fuel injectors. The high pressure side typically runs at about 500 psi at idle, 1,200 psi at about 3,300 rpm and about 3,600 psi under full-load acceleration.

This system involves a high pressure oil pump and an IPR (Injection Pressure Regulator). Sticking (or wear) problems with the high pressure control regulator can cause engine surging (most commonly noticeable at lower rpm and at idle), as well as intermittent engine shut-off during low speed braking and/or when approaching a final stop.

If the engine cuts out during a stop, with the transmission placed in neutral or park, the engine fires up again, but dies again when approaching a final stop. Other symptoms can include intermittent difficult starting, a slight stumble when the accelerator pedal is nailed while the engine is turning around 1,000-1,500 rpm and/or annoyingly extended cold-cranking in freezing temperature. Granted, various injector issues could cause some of these problems, but if a customer’s truck enters the shop with the surging/intermittent shut-off issues, definitely inspect the high pressure oil system.

I’ve owned several Ford F350s with the 7.3L Navistar turbo diesel, and have experienced this identical set of issues (most notable on my 2003 model). When these drivability problems began to appear, the “off-the-cuff” reaction was to replace the fuel filter, suspecting that it was moisture-contaminated.

While it’s imperative to regularly replace diesel fuel filters anyway (especially in cold climates), if the first few filter changes don’t solve the glitch, suspect the high pressure oil control valve or regulator. The high pressure oil system runs at very high pressure, and any interruption in pressure flow will cause the ECM to attempt fuel enrichment changes.

NOTE: While it’s certainly easier to replace a sticking control valve, the high pressure control valve is usually rebuildable (basically just disassemble, clean and reassemble). Also be sure to check the high pressure oil rail and its connections for external leakage (which will not only make an oil mess at the rear of the intake manifold, but will cause pressure drops).

It’s also important to remind customers that only specified engine oil should be used in diesel applications, in part because of the special anti-foaming additives in the oils, critical for maintaining an adequate and constant pressure to the injectors to prevent aeration and sub-par injector spray patterns (these anti-foaming agents can break down in the 3,000- to 5,000-mile range). Citing the Ford examples, several oils are appropriate and should carry an API rating of CF-4/SH or CG-4/SH or higher. One example is Shell Rotella-T 15W40."

http://www.fixya.com/support/r7995890-d ... ges_stalls (and look at the end where it describes the following: "Manifold Absolute Pressure Sensor failure symptoms: Engine will rev or surge suddenly, possibly causing the engine to sputter and die. May also surge while idling, such as at a stop light. You may also notice the engine idles rough when the car is on but not driving down the road."

Does this apply to our Jeep Liberty CRDs as well?

Any insights would be appreciated.

thanks,

Sarma.

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2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.

Sorry, but people here have been doing this for years here with no surging issues. It is the "ORM" in the Newbie guide.

However, ORM is now known to be much less effective than was once thought in terms of reducing EG ingestion/soot in oil.

DOC

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2005 KJ CRD Ltd Detroit TrueTrac Bilsteins G2 GDE "HOT" ECU GDE TCM "Tow Tune" "euro" TC SEGR Weeks Elbow New HG at 130K ARPs Clean CAT aFe Filter Magnaflow Exhaust EHM Cumminos In-Tank Lift Pump Hayden Fan Clutch Nylon Fan VH Enabled with GDE lower shutoff point Recalibrated Temp Gauge Tekonsha Prodigy Sears P-1 ZDDP

Thanks Doc,

I figured that was the case, since so many people reinforced unplugging the MAF.

I guess I'm going to have to go back with a fine toothed comb and check all the work the mechanic did (and things I've done) to try and figure out what might have caused these symptoms to start (or combination of doing the work may have loosened up something / caused something to malfunction).

Mechanic did:
* new Timing-Belt/Water-Pump kit
* new Thermostat and Thermostat Housing Assembly
* new Intercooler
* new Glow Plugs & Controller Unit
* new Fuel Filter
* new Oil filter
* Front & Rear Differential fluids changed
* Transmission fluid changed and Transmission filters (guess there were 2 different filters) replaced
* Grease/Lube the sway-bars
* (5) new Tires and Stems, alignment, rotation, & disposal fee
* new Engine Mount installed

Items I did:
* Researched the symptoms, and learned about the dreaded "air-in-the-fuel-line" problems with this CRD - and was able to determine that it does have the 2nd generation Fuel Filter Head (heater plug housing differentiation).
* Cleaned the MAP Sensor
* Bled a lot of air out of the fuel line through the primer nipple, routinely
* Put in a new higher performance Air Filter

I've researched about the ECU/TCM update-flash from the stealership, and this helped fix someone else's engine-surging issue, yet I'm not sure if it will fix mine.

We'll see.

Thanks again for your perspective.

Sarma.

_________________
2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.

Neither one of the explanations for surging in your quote from the article apply to the CRD, because it doesn't use MAF rate to calculate fuel injection quantity like a gasser does, and doesn't have a high pressure oil pump like some diesels do.

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05CRD: GDE Hot ECU & TCM tunes, Provent, Cat filter, Facet lift pump, TransGo kit, Florida TC, Samcos, stainless brake lines, HDS thermostat, Renegade light bar,
RL super sliders, Bilstein adjustables, Al's Gen 4.5 Arms, 235/85-16 Duratracs, DTT rear, Elocker front, EVIC+TPMS, Turbo timer, McNally pillar gauges, Weeks Stage II kit.

Thanks CATCRD for the 411 ... that is a huge relief.

I can stop going down that research line now.

HURRAY!.

Now to figure out why the KJ is doing this at stops (when it is cold).

Hopefully the mechanic finds something definitive, and fixes it free of charge.

*crossing-my-fingers*

Thanks again for the information.

Sarma.

_________________
2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.