diagnosis please : Revs stay up

[aurace]

what could be the cause of this.
If i have the foot down to highish in the rev range (5 - 7) - when i back off the revs still stay up for a second or so.

I can hear the bov working so i know the throttle has closed.. but revs still stay up.

any ideas?

 

[87vr4]

does the tacho continue to rise? or does it just hold the exact rpm u took ur foot off the juice at.

also is it the same if u hold say 6k & then take ur foot off, or is it only when ur doing quick changes?


if ur throttle is closed then u have no air, ur missing one of the fundamental elements which allow the car to rev in the first place...

check to make sure the butterfly is snapping closed, maybe the return spring isnt up to the job anymore

 

[aurace]

throttle definitely snaps shut - and bov vents. (has a big return spring and all moves freely)

tacho stays up and revs stay up audibly.

only notice when doing quick changes - but it does happen if i take it up to 5/6k rpm and take foot of accel.


im starting to wonder if it is the safc decel function which i thought does nothing on 4g63's ?

 

[JAP63]

U dont use the deccel functionat all.
Ensure ur car is set to Karman type sensor..Cylinders on 2 etc etc...
Check the freeplay in your throttle cable,check for free operation and return also.

If you think its ur SAFC.
Tell me your values and settings.
I'll compare them to mine and see if theres a problem

Maybe ISC aswell,the idle stepper motor.I dont know much about it though.
It usually only plays a roll at idle though

 

[Jayz-1]

My car was doing the exact same thing, had no idea what it could be, checked everything... then i unpluged the ISC and was driving it and it went away...
changed the ISC and throttle body and it still does it...
No idea what is causing it, started to happen when i did custom plenum...
now i just ignor it and have learnt to drive it without it soulding like im a shlt cvnt that cant drive and mis times the clutch.. haha

Just try unpluging it and then go for a drive (might not idle 100%, so you might have to adjust the idle screw), but its a easy free thing to check...

Let me know man

Jason

 

[aurace]

the safc is zero'd out.

How does the cruise/throttle setup work? i see 2 cables going into the cruise control box and 1 out. Any serviceable parts in there?