this is for all the friends who have FF cng setup;
i recently purchased a car with FF CNG and a few days ago i was servicing throttle body, TPS, IAC valve and noticed that on the air filterbox end the pipe was blocked by half tin can with holes in it while on the throttlebody side of the pipe there was genuine venturi (http://nagaz24.pl/uploaded/product/mini3_924_5.jpg) already installed. I also noticed heavy sludge on throttle body and airfilter pipe also the IAT sensor was full of black thick oily stuff. So i cleaned every thing with Carb cleaner, removed the blockage (tin can) and set the CNG setup by turning the T-bolt etc.
Searching about the sludge, i found that a bad PCV valve could cause sludge, oil reduction and random smoke. After inspecting the pcv valve it was discovered that pcv valve was broken from valve cover end and the spring was not in it. After opening the tappet cover spring and its piston was found there.
A new pcv valve was available for 1200 however a kaabli one was available for 250. After servicing all above and replacing PCV valve all these problems were solved;
- no random smoke
- no oil reduction
- smooth idling
- better mileage
- better acceleration
- no rpm fluctuation
- no backfire
Just dont block the air (if you have "nasli" venturi installed) instead get your car properly tuned for CNG it will save your :-$
Broken PCV Valve;