just started yesterday evening- applying part throttle results in a "surging" or jerky accelleration. WOT is smooth and idle is smooth. Taking car in to dealer tomorrow- any thoughts on what it might be?
The surging / jerky effect is slight but very noticeable.

 

It could be bad gasoline. Did you fill up recently?

 

yep, but it did not happen the day of fill-up - about 2 days later. Was thinking bad gas too, but it's the same place I always fill up at.

 

Hmm. I still wouldn't rule out the gas, especially if it had ethanol. I'm no expert on this topic, but my understanding if that if there is too much water in the tanker delivering the ethanol gas, it can be the cause of sluggish performance.

 

I never buy gas from a station when the tanker is there filling up the underground tanks. Also, about twice a year, I add dry gas to my gas tank.

Harvey in MD

 

A somewhat common issue to some 05 and 06's and has something to do with the drive by wire and throttle plate...this has been discussed here and on Rennlist many times.

 

Mass air flow sensor? WOT is a open loop map and wont rely on the sensor so that could be a reason why it works fine wide open but poor at part throttle.

 

Thanks guys- I agree, MAF and TP were on my list of suspects. If it were the MAF, wouldn't idle be erratic as well? Time to flex that warranty first thing in the a.m. - I'll post back what the outcome was.

 

I'm curious to see if your dealer will have anything to say about your exhaust, plenum and intake in regards to your warranty and your jerky acceleration.

 

We'll never know- I presently have stock mufflers on and took out the RSS today. KN stays, that would be pretty weak on dealer's part to blame the intake. but we'll see.

 

This happened on mine too,it could be the flow of my exhausts and high flow cats. I am going to replaced the orig cats back to try.

 

^ fyi I experienced issue with stock exhaust / cats so that may not be it.

 

took car in to dealer today. it did not do the jerky thing at all driving over, ran perfectly fine. Of course this was the first drive after removing the RSS plenum yesterday (didn't want dealer to give me crap), so if they do not find any faults i'll put the plenum back in and see if it happens again.
Oddly I noticed the inside of my plenum is rough / unfinished bare aluminum, i'll have to ask Greg about that.

 

The surging issue occurs infrequently to some 997's, usually on a partially full tank. It never leaves a check engine light. Cures for this, posted on the rennlist forum, were to fill up the gas tank or remove and reset the fuel filler cap. Nobody has ever provided an authoritative explanation. The dealers do not acknowledge it.

 

Thanks for your insight Michael- If it comes back I'll try the suggested fix. Dealer is not finding anything wrong.