My 2005 Liberty CRD is surging at idle and under power.

kevink · **Joined:** Sun May 08, 2011 8:44 am **Posts:** 5

Does anyone have any idea what would cause this surging? Power is fine, engine runs smoothly and quietly but there is this surging every 2-3 seconds. You can easily hear it at idle and you can feel a subtle surging while under light to medium power. Frequency does not seem to change whether the jeep is moving or not. I recently got the GDE eco tune installed. No codes are showing.

AZ CRD · **Posted:** Mon Jan 26, 2015 9:59 am

Mine does something of this sort when the heater's on and the fan selector is in the floor, floor/defrost, or defrost positions.

PALiftedKK · **Posted:** Mon Jan 26, 2015 10:24 am

check fuel line pressure.

kevink · **Joined:** Sun May 08, 2011 8:44 am **Posts:** 5

Thanks AZ and PA for the speedy replies.

I will check the fan thing today.

Fuel line pressure where? In supply line from tank? After fuel filter? Is there a special gauge that is needed?

KK

PALiftedKK · **Posted:** Mon Jan 26, 2015 11:59 am

im not very familiar with the crd set up, but check the pressure nearest the engine. there is most likely a write up about this online some where. if the pressure looks fine, check the injectors. replace the air filter recently?
something like this would work.
http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

papaindigo · **Posted:** Mon Jan 26, 2015 1:31 pm

What AZ CRD is referring to is the fact that the AC compressor cycles when the AC is "off" and heat is on in certain vent modes. Easy check is to switch vent mode switch, the center one, to "O" to turn the system entirely off. If "surge" goes away it's the AC compressor cycling in which case you might want to get the AC system pressure checked.

thermorex · **Posted:** Mon Jan 26, 2015 2:25 pm

PALiftedKK wrote:

im not very familiar with the crd set up, but check the pressure nearest the engine. there is most likely a write up about this online some where. if the pressure looks fine, check the injectors. replace the air filter recently?
something like this would work.
http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

As this advice would work great on a gasser, it doesn't do to much for the diesel, and I think you mistakenly thought this is a gasser question

. The easy way to test the pressure is connect an obd2 reader to the jeep and monitor the rail pressure. The gauge above would blow to pieces when you just crank the engine, as there are several thousand psi. You also can't connect it anywhere (luckily) in the Crd.

Surge can be caused by air in fuel, bad injector(s), or something on the fuel delivery. My bet is some air in fuel. Check fuel filter and fuel filter assembly (look if you have 2nd gen unit) as first gen is known for leaking air through. If you don't experience power loss though, it's not very likely to have air in fuel...

+1 to papa, this happens in the winter when ac goes on and off, as it's cold it makes a very quick cycle.

PALiftedKK · **Posted:** Mon Jan 26, 2015 2:30 pm

thermorex wrote:

PALiftedKK wrote:

im not very familiar with the crd set up, but check the pressure nearest the engine. there is most likely a write up about this online some where. if the pressure looks fine, check the injectors. replace the air filter recently?
something like this would work.
http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

As this advice would work great on a gasser, it doesn't do to much for the diesel, and I think you mistakenly thought this is a gasser question

. The easy way to test the pressure is connect an obd2 reader to the jeep and monitor the rail pressure. The gauge above would blow to pieces when you just crank the engine, as there are several thousand psi. You also can't connect it anywhere (luckily) in the Crd.

Surge can be caused by air in fuel, bad injector(s), or something on the fuel delivery. My bet is some air in fuel. Check fuel filter and fuel filter assembly (look if you have 2nd gen unit) as first gen is known for leaking air through.

+1 to papa, this happens in the winter when ac goes on and off, as it's cold it makes a very quick cycle.

true. I forgot about obd. possibly water in the tank? I know WAWA has trace amounts of water in their diesel. I know from personal experience because my last job had 3 engines down in a months time with a water filled fuel filter.

greiswig · **Posted:** Sat Jan 31, 2015 3:37 pm

Just a thought: I have a little surging in basically one area of accelerator pedal travel. To me, it feels like a worn or dirty spot in a potentiometer that might be being used as the accelerator position sensor. Hasn't gotten bad enough for me to look into it, but...

My 2005 Liberty CRD is surging at idle and under power.

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