Happened for the first time after IPD 82mm plenum+TB upgrade, so i think is somehow related to this upgrade, dont think it is from the TB or plenum, but maybe vacuum related or so...

Sometimes my idle stays at 900-950 rpms as usual, sometimes rises till 1200-1400 or even higher... i have seen even 1600 rpms

Very often when shifting gears i feel the car tends to rev a lot when going through idle point, if i shift fast enough the engine can not gain rpms to give me that feeling... anyway.. when i am granny shifting sometimes i see the engine revving till 4000 or so... if i let it for 10 seconds will get back to normal for a while... if i hit the gas will go even higher rpms and then after another 5-10s will get to normal... this is driving me crazy !!!!!!

A few days ago it happened when i was waiting for the green light near a tram station and an old guy was looking at me like... man you are crazy and ridiculous, stop doing that !!! i didnt know how to explain to this guy.. i can not do anything !!!

I did some logs.. at idle the TB stays like 3.x% open...
I did a lot ( and i mean a lot ) of boost tests.. from turbos to TB, from TB to the engine... everything looks just right... car is holding the pressure... even runs like a champ 99% of the time, just that once at 5-10minutes does that...

Also did a TB calibration, double checked with my tuner.. there is no need to change tune whe doing TB upgrade

the last thing i am going to do is to put back the stock TB and see if it happens again... just wondered if anybody else had this situation before..

 

Are you running MAFLESS ?if yes this is expected when you run bigger plenum/TB.that happened to me and Todd.K@protomotive solved the issue with a retune.drivability is like stock.

 

Yes it does need a retune. The car is searching for idle.

 

I ve been told it doesnt... And yes i run a mafless tune from todd.. I will ask for a retune.. I wasnt expected to be so easy . Thanks a lot guys! Help much appreciated

 

sounds like a tune problem OR vacuum leak from a check valve on he IPD.

i can tell you this much 3% open at idle on 82mm TB is way too much. my TB idles at 1% and its a 75mm. on another note i dont know why ppl put 82mm TBs on when you can make over 1100 even 1200 on a 75mm without introducing driveability issues like these.

 

pre cat O2 sensor. Ask me how I know.

 

I'm going to add to the list of options. At idle some air flows through the checkvalve that goes to the oil tank. I know IPD apparently fixed this with an updated version of the check valve, but when I blew through the new valve it definitely flowed more than the stock one. Todd told me to reduce the line size to the check valve - which I did.


Now considering you went 82mm, I am guessing you have the 997 setup. I bet that valve flows differently again.

 

ohhh great .... Yes i have the 997 version...

At least we can all learn from my bad experience, so till now the options are :

- Boost/Vacuum Leak - already checked 3-4 times, will redo, pending
- Tune, mail sent to Todd, pending
- O2 sensor, i will check with durametric and see what i can find, i'll start with AFRs
- CheckValve


I did 82mm just because i thought it is better and has more scalability for future upgrades, funniest thing i ordered the 74mm, didnt open the pack and paid again shiping to and from US for the bigger one... i also did the 82mm to be able to bolt on the gt3 intake mainfold..

 

If you log it you will find your AFR lean at idle and partial thottle,usually when running bigger TB/plenum no need to retune if running MAF but since you are running Mafless you need definitely to retune it.

 

Any update?

 

Changed the check valve with the old one, still did those problems but only when shifting... i didnt even realise that lately it worked perfectly, but to be honest drove her WOT or very easy... the problems where exactly when shifting at 5000rpms for example

Idle is much much better 950 rpms for 99% of the time, sometimes gets up a bit 100-200 rpms... and i run the 996 intake mainfold not 997... i had to do some modifications inorder to fit