Intermittent Surging at idle

DieselJeepLuvr · **Posted:** Tue May 23, 2017 1:26 pm

I am having intermittent surging / lope that occurs while in park during my turbo cool down period. Doesn't happen all the time so it's hard to troubleshoot. I tried to pull the codes but maybe I'm doing it wrong. I was told to turn the ignition on 3 times then watch for the pattern of flashes on the dash but I don't see anything. Suggestions?

mass-hole · **Posted:** Tue May 23, 2017 1:48 pm

Is your A/C on? Even it the A/C button is not pushed, I believe it is automatically engaged if you have it in any of the last three positions on the vent selection knob(the defrost settings in particular).

DieselJeepLuvr · **Posted:** Tue May 23, 2017 2:51 pm

Can't remember what vent settings were being used. AC was not on though. How could the AC compressor affect idle quality?

cerich · **Posted:** Wed May 24, 2017 11:44 am

the ac compressor is run on the accessory belt, so when it engages (has a clutch) it puts a load on the engine

Mountainman · **Posted:** Wed May 24, 2017 2:25 pm

A little air in fuel, or an injector acting up are my guesses. I have an injector that was only doing that when it was cold, to now it's starting to act up when warm. It acts like it isn't firing, so I'm going to start by seeing which one returns the most fuel...

papaindigo · **Posted:** Wed May 24, 2017 3:35 pm

Can I assume your RPMs fluctuate when it does this? If so how much?

Doubt it's the AC at least I've never noticed compressor kick in/out having much impact but it might be worth turning AC on to see. Compressor cycles in all, or most all, vent positions but bilevel even of AC switch is off.

mass-hole · **Posted:** Wed May 24, 2017 5:56 pm

DieselJeepLuvr wrote:

Can't remember what vent settings were being used. AC was not on though. How could the AC compressor affect idle quality?

As it cycles it would load and unload the engine which means the engine would need to compensate which is not instantaneous. Watching torque pro my engine might be at 15% load at idle with A/C off but around 30% with it on. When the engine goes from A/C off to A/C on the rpms will momentarily dip slightly and when the A/c goes from on to off the rpms will jump slightly.

The A/C light wont be on if the button is not pressed, but it is in fact on if you are in one of the defrost settings, so sitting in the car it would not be obvious it was engaged.

DieselJeepLuvr · **Posted:** Thu May 25, 2017 11:41 am

AC was off. Selector was in the vent position. Only did it after engine was hot and in park during turbo cool down period. lope was about every second like a big cam race car. Started from negligible to almost stalling the engine in a matter of about 20 seconds. As soon as I bumped the throttle it would stop then gradually start again. I have not been able to duplicate this recently but have been using the AC so my guess is if there is a load on the motor such as the AC or it being in gear the lope will not occur.

Just for reference I have just purchased this rig (my second CRD Libby), cleaned the MAP sensor, did the EHM and unplugged the MAF.

APC9199 · **Posted:** Thu May 25, 2017 12:09 pm

I like to start with the basics. Do you have the new version fuel filter head installed? How old is the fuel filter that is currently on the vehicle? Do you have a lift pump installed and is it IN or OUTSIDE the tank?

That type of behavior sounds to me like intermittent fuel starvation or air in fuel. The problems above (or the solutions thereto) are good preventive maintenance and longevity enhancers, so I would recommend considering them either way, if they have not been implemented already. If those have all been taken care of, then we'll consider the next option...

DieselJeepLuvr · **Posted:** Thu May 25, 2017 12:30 pm

Sorry should have added that. Yes, appears PO had new filter head installed. No idea on age of FF but considering it was a Dodge dealership loaner vehicle for 2 years I'm assuming it's been kept current. I do plan on replacing it next oil change.

APC9199 · **Posted:** Thu May 25, 2017 5:06 pm

DieselJeepLuvr wrote:

Sorry should have added that. Yes, appears PO had new filter head installed. No idea on age of FF but considering it was a Dodge dealership loaner vehicle for 2 years I'm assuming it's been kept current. I do plan on replacing it next oil change.

There's your problem right there!

usa591 · **Posted:** Fri May 26, 2017 8:57 pm

I, too, am having this problem--sounds eerily similar.

Engine runs fine for the first 20 minutes or so, then when I'm idling at a stop sign after it warms up, it starts to "run rough", "lope" or "chug".

No CEL.

I installed the in-tank Cummins pump and the engine doesn't "lope" as hard, but it still does it. Before the pump was installed, it was bad enough that I had to put it in neutral or I was afraid of it stalling.

New fuel filter, new head. Primer pump is now hard as a rock with the lift pump.

Even though I've been running the EHM/ProVent mod for many miles, I was going to clean the MAP sensor this weekend to see if it helped anything.

Ideas? The dealership too a look at it and had no idea (didn't even know they made CRD's). They said they would have to contact Chrysler for guidance...forget that.

Any ideas?

rankom · **Posted:** Fri May 26, 2017 9:39 pm

disconnect , battery , and remove ECM harness then check and clean it , possibly one of injector harness connectors loosing connection .

GordnadoCRD · **Posted:** Fri May 26, 2017 10:22 pm

If it sounds like it's a single cylinder weak or missing, carefully pull the electrical plug from one injector at a time, then plug back in before pulling next one.
If you find one that makes little to no difference, or that the intermittent problem becomes constant, then you've found the problem cylinder. you can also do this with a cylinder kill test if you have a scanner with that function.

A bad or incorrect torque on an injector, missing or damaged chamber gasket, low compression, excessive valve lash, flat lobes on camshafts could all cause a miss.

Actual versus desired fuel pressure too far apart; map the actual fuel pressure vs. the set point pressure, if erratic and there is no air in the system, it may be a bad Fuel Quantity Solenoid (fuel control actuator, MPROP, etc). If you have a fluctuation over 500 PSI this can cause a surge. Fuel contamination can cause the Fuel Quantity Solenoid to become sticky and erratic.

Turbo VGT system leaking vacuum, sticking, that's more low speed than idle though.

WWDiesel · **Posted:** Sat May 27, 2017 10:49 am

With it only showing up when engine heats up at idle, I would suspect a wiring or connectivity issue or an injector trying to go bad...
Try jiggling the wires and wiring harnesses in the engine bay area when it starts doing it and see if it makes any difference.

Locate a good diesel injection shop in your area and seek their professional help and advice! :wink:

Stay way away from dealers as most are clueless on this engine! :banghead:

See this website:> https://oregonfuelinjection.com/

DieselJeepLuvr · **Posted:** Sat May 27, 2017 12:31 pm

Thanks! Good advice and it makes sense it being electrical due to it being intermittent. Just dawned on me if it is a poor quality connection it would be more prevalent when the engine is idling since it "shakes" more.

DieselJeepLuvr · **Posted:** Tue Jun 13, 2017 12:34 pm

Update: Last week I changed the oil / fuel filter and headed out for a road trip. Then my tranny failed... Brought it back home with a new tranny and installed the Weeks stage 1&2 EGR delete kit and cleaned about a pound of soot buildup out of the intake manifold. Also reloomed a bunch of wiring on top of the engine that had gotten brittle exposing wires (one having a bare spot). Now I don't seem to have an issue anymore though it was intermittent before so only time will tell. It may have a very slight lope now but then again maybe it's just my imagination... So IF it's fixed it it was either the fuel filter, 2/3 intake restriction, bad wiring or whatever. I'll keep you posted.

Intermittent Surging at idle

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