Hey guys. I have a problem that i do not have any idea what it is related with. I read the forum everbody says it is related with bov but mine does it below 2000 rpm too. When i let off the gas the air fuel ratio is increasing to the maximum on the gauge and vacuum pressure drops to -32 and shows only lines. What could be the problem?

 

AFR should go full lean, and you should see maximum vacuum when decelerating in gear. As far as the jerking, are you being smooth with the throttle? With a manual trans, you cant just chop the throttle off like you can in an auto. You have to roll off smoothly or the car will jerk..

 

lol, welcome to driving a manual car. I won't be a dick about it, but you might want to go read up on vacuum/boost pressure and AFRs, as well as how an engine works during acceleration/deceleration.

Nothing is wrong with your car, but when you're in 1st/2nd gear and you quickly let off the gas pedal (chop the throttle) it's going to jerk forward. Your car is fine.

 

This is not the first manual car i drive. I am not changing gear. I just letting off the gas pedal. It really jerks badly when letting off the pedal. Could it be related with IACV? i read about faulty iacvs and it seems like it is the problem in my car.

 

Exactly. The Evo isn't a "smooth" car. You have to very smooth with the throttle or the car will jerk when letting off.

 

It never hurts to clean the throttle body/IAC valve with some carb cleaner.

 

Do a snap throttle and see how the idle stabilizes.

 

Could also be a lightweight flywheel, or timing retarded too much in those cells

 

sounds like timing is not right could be tune, or incorrect physical timing of course a video or more info would be very helpful

 

I will place a video today to show you how the car reacts when letting off the gas

 

Hi mate, did you get your issue sorted? Mine does the same thing in drive, no matter which gear. Higher gear bit less noticeable. Does yours do this at nuetural?