I had this problem on my 2006 innova j gas. the problem is the aircon design at the back.
Dito pumapasok yung outside fumes:
1. Yung air flapper/side vents (not sure what this is called) located sa side ng rear bumper (left and right)
2. yung bakal sa likod ng bumper. you will see this pag tinangal yung bumper. you will notice puro butas yung area na yon.
Solution from TMP c/o Toyota Pasong tamo:
1. Permanently takpan yung left and right flapper.
2. Permanently takpan lahat ng butas sa bakal.
Effect:
Hinbdi kagad masara yung mga doors dahil hindi kagad makalabas yung excess air.
Yung excess air lalabas sa left and right side ng dash board.
After 5 years I sold my innova. However, I bought another 2011 innova j gas. Surprisingly, ganon parin!
This time ako na lang gumawang solution 1 & 2. I used vulcaseal
Dito sa office namin we have 3 innova j gas and 1 innova g gas. Lahat sila has the same problem on fumes entering the cabin. Im just surprise bakit hindi ito major issue sa tsikot.