Rev hang question

[Savir04]

hi guys

I have a question, I am experimenting with the oem maff housing coupled with a cone filter on a stick....I understand the maff configuration on this car is super tricky

heres a pic of my intake (still a work in progress) (disregard the random turbo lol)

MY question is, if i let off the gas anywhere UNDER 3k rpms, I get nasty rev hang, seems like the Thottle Body does not close completly...only happens anywhere under 3k rpms....if i let off the gas anywhere over 3k rpms for example, let say i rev up to 4200 rpms and then let off, the throttle body closes, engine goes into "gargle/backfire" mode and rpms drop down quikly, like it's suppost to

with the maff sensor unplugged, i do not get any rev hang what-so-ever in any given RPM, BUT my fuel trims all go to shit with it unplugged

so my question is, If i am getting rev hang letting off the gas under 3k rpms, does this mean that the maff sensor is measuring too much air or too little air than whats actualy going in?

 

[nashbar]

vacuum leak. you probably broke that little EVAP/brake booster check valve thing.

 

[eod69usn]

yup...check all lines and valves for broken/cracked fittings

 

[//GTI_Fast07]

When I had a rev hang issue it was after getting a aftermarket intake where the MAF stuck out far like yours does. My GTI is an 07 and when I bought a new intake the MAF plugged in more flush with the pipe and the issue was gone. I guess the positioning of the plug's depth can make a big difference.

 

[Savir04]

my maf sensor is in its OEM housing

 

[NJdubber]

That screenshot of your engine bay scares me.. check your vacuum lines, intercooler lines, DV, THAT PCV setup you got going on and check for codes... Last but not least, LOG!

 

[ricewithsticks]

How long does the rev hang? When I let off the gas in my car the engine revs a little, kind of in sync with the blow off of the intake. Is that rev hang?

 

[razr]

i also have rev hang but just for a second and then it drops down. vacuum leak? i was thinking stuck throttle body?:iono::iono:

 

[Wabbit1]

Could this be an exhaust leak causing the same rev hang issue?