for all those with surging idles...long
 

well, i just got to the root of my surging upon startups. i have been trying to tune everything possible in order to get rid of it. i knew my fuel pressure and timing were right on the mark...

so i then began to think that it had to be mechanical. i started to think about how i had my PCV system now then when my idle was smooth.

i had put a breather in place of the oil cap!

so then i was thinking that since i had the PCV still hooked up in the back of the intake there had to be a huge vacuum loss because i didnt have the tube that goes from the throttle body to the oil neck anymore. the PCV was just pulling air in through the breather i had put on. there was a HUGE vacuum loss!!

what i did was instead of putting the tube back on that goes to the throttle body. i just put a airflow control valve inline of the PCV. so i could keep the vacuum down so it wouldnt be such a huge loss, yet keep enough to evacuate the crankcase gasses.

that little valve solved ALL of my idle problems.
i just wanted to let you guys know because i know there are a lot of people out there that have idle problems...

hope it helps,
adam

Your problem was caused by unmetered air introduced into the engine, the result of the open oil breather.

exactly!

thanks,
adam

I just put one of those breather caps with a filter and i havent noticed any difference in performance or drivability. I left the tube on though. Are you not sopposed to put breather caps on an efi engine? I just did it because it looks cool lol.

Later,
Nick

well, thinking about how you have yours setup. you have a loss in vacuum too. because the PCV system is then open to the atmosphere and not being metered. i dont know how you are not experiencing any problems....

take care,
adam

I have tried replacing the oil cap instead of the breather to cure a surging idle problem, and it didnt change anything. Im glad this fixed your car, but I dont think its the answer for everybody.

im not saying it is, just trying to give other people ideas...

adam