Surging at idle in park.

navyCRD · **Joined:** Mon Mar 12, 2012 7:02 pm **Posts:** 15

I've read a few posts on here and they all ended up being the trans however their surge was in gear. My engine was warm and was every 8-10 seconds the engine would bog down, dropping 25-30rpm. Then if I would accelerate lightly and slowly bring rpms down to ~800rpm it would run rough until I let off or accelerated again. Sounds like fuel to me but hey I'm not expert. Anyone ever have this issue before? Thanks in advance!

flash7210 · **Posted:** Mon Oct 14, 2013 10:13 pm

Is the A/C on when its surging?

navyCRD · **Joined:** Mon Mar 12, 2012 7:02 pm **Posts:** 15

No. The heater was however. The vehicle had been on for awhile and was at operating temp. Haven't looked for it on start up yet. I just noticed it this evening.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Could be a partially clogged EGR, leading to cycling on the intake throttle. Unplug the MAF and see if it goes away.

dgeist · **Posted:** Tue Oct 15, 2013 3:41 pm

GreenDieselEngineering wrote:

Could be a partially clogged EGR, leading to cycling on the intake throttle. Unplug the MAF and see if it goes away.

The EGR is triggered at operating tempurature while the engine is idling and in park? Wow, I'm more and more glad I have "alternate control techniques" for the soot pump every day...

BTW, I'd also pop the hood and see if the idler pulley is mostly stable in its movement. A little wiggle is normal, but a sharp jerk could be indicative of a failing bearing and that might cause a sudden decrease in idle speed if it's catching badly enough.

Dan

navyCRD · **Joined:** Mon Mar 12, 2012 7:02 pm **Posts:** 15

I was told by the previous owner that the egr was disengaged. Do I don't think thats it. Idler arm looks good as well. Today it hasnt surged at all so maybe it was a fluke?

MRausch82 · **Posted:** Tue Oct 15, 2013 4:22 pm

Is the heater position set to "floor only?" If so, it is engaging the AC compressor and will cause a drop in RPM... though the rough running issue has me stumped. I agree with GDE on the EGR being stuck, that is certainly a possibility. Change your fuel filter if you have not already done so. Should be done around 15-20K in my opinion. I do mine twice a year, usually between 10-15K, but that is because I service my vehicles more often than most do...

navyCRD · **Joined:** Mon Mar 12, 2012 7:02 pm **Posts:** 15

I haven't replaced that in over a year! Yikes! Guess I know what I'm doing this weekend!

Surging at idle in park.

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