Random high idle problem

[EyeluvSmegma]

After my car is warmed up, driven maybe 20 highway miles and now onto side roads, I get a random high (12-1500) RPM rev up. My foots not hitting the gas and it usually happens when coming to a stop light and in nuetral or going to nuetral. It will last for 2-4 seconds and would t do it again for a few days. Anyone have a clue? Found nothing on the web other than rough idle for PCV. Thank you l in advance.

 

[Llia]

What year is your car? Mileage?

 

[EyeluvSmegma]

What year is your car? Mileage?

2013 1.4 6spd. Has 42,000 on the clock

 

[Llia]

Does it happen when the A/C or heater is running? Possibly at full blast?

 

[EyeluvSmegma]

Does it happen when the A/C or heater is running? Possibly at full blast?

I usually don't have the AC on.... Happens without it on. I know it will idle up on the seldom times I do use it, but it's a steady 100-150 rpm increase.
The issue I'm having is comparable to sitting in your car in the driveway and goosing the gas to 1500_2000 and holding it there for a second. Sometimes its quick and others I have to bump the gas pedal and it's back to normal for a few days. It's the weirdest thing really. I've changed my valve cover, MAF, detuned it, put my stock I take back on. The only thing I haven't taken off is my exhaust/downpipe. Only does it coming out of gear going to "N" or in "N" when I very first start to coast to a light or stop

 

[UltimaSanctus]

Im actually curious as to what this is cause i havethe same random issue. Usually happens when im coming to a stop and pull it out of gear at lets say 20mph it will give a slight rev as if i was going to rev match and downshift. I did hear a thing about these computers "learning" our driving styles so maybe it is trying to help rev match. Probably not

 

[EyeluvSmegma]

Im actually curious as to what this is cause i havethe same random issue. Usually happens when im coming to a stop and pull it out of gear at lets say 20mph it will give a slight rev as if i was going to rev match and downshift. I did hear a thing about these computers "learning" our driving styles so maybe it is trying to help rev match. Probably not

I'm guessing we are the only 2 with this issue?

 

[Ian_12]

I get it too. It's usually a vacuum leak of some sort. But due to fly by wire, and emissions, it could possibly open throttle briefly to reduce emissions. By vacuum leak it could be many factors like a slow response pcv.

Until the rpms hang for a while, I'm not bothered. It's a minor thing and I think it could really be emissions related. Datalog could solve the mystery.