Minor annoyance, but lately as I come to a stop the idle dips down, then a second later picks up. Will also do this with change in engine load (e.g. fans kicking on). It acts like it has a dirty idle air control, but of course this engine has no IAC. I've cleaned the throttle body and there's no sticking issues there. Only seems to do it when the engine is hot. Anyone run into this? No issues otherwise. No odd fuel trims.

Thanks,
-Michael

 

Going from memory here, but it seems to me that I had something similar to this as a sign that my MAF sensor was about to pack it in. Eventually it did, and I replaced it, and haven't had this issue in awhile. Which is good, because it is keeping me busy in other areas...

 

If your O2 sensors are original, it may be time to replace them. They can start going bad with age without throwing codes.

Otherwise, I would say you have an air leak somewhere, but you say your fuel trims are good.

 

TPS?
Suggestion: Have you tried resetting your accelerator pedal as if you were doing so after a battery disconnect?

 

I don't see how TPS could cause it. There's a minimum target for revs.

It can cope with TPS of zero...

 

My apologies....I had an erratic idle when I forgot to reset my throttle after a battery disconnection which went away when I pressed the pedal through the détente to the floor a few times with the ignition on but the engine not started? My situation must have been different or just a coincidence...

 

There's no harm doing that - the PCM just watches and stores any min or max outside the values it already had.

It then treats those in effect as 0-100% internally.

 

Thanks for all the replies.

Ayavner, that jogged my memory and I remember the same thing happened to me as well--but I replaced the MAF sensor with a new OEM 10k miles ago. Hopefully this is not bad again or some intermittent electrical issue.

Front O2 sensor were recently replaced with OE. I left the rears for what it was worth. I did check on the fuel trims again, and sitting there at idle they just bounce around 0% with the most excursion to +/- 3%.

My throttle body is going on 124k miles and 13 years, maybe it's just getting worn out enough to cause this minor issue.

 

Did you find a resolution to this issue?

 

No, I'm decided to move on from this car, haven't looked into it any further.

 

I'm sorry to hear that Michael, I hope you have another X350 in mind, because you have been a genuine font of knowledge for us in electrical matters!

 

I had that happening about a year ago. Looked at the throttle body and even cleaned it (and throttle plate) with no avail. A road trip to Flagstaff and back and it hasn't happened since.
FYIW...