R34 Rb25Det Idle / Backing Off Issue

[mystery_kid]

Hello gang,

so for a while now my car has been doing some weird and annoying shit, it happens mostly when i back off the accelerator - it's like the throttle doesn't back off completely, it will still cruise almost on it's own before finally backing off. same when i change gears because the revs don't drop off properly sometimes it sounds like when you get back on the revs to early when changing gear

also at idle sometimes, not that often but sometimes it will just climb in revs up to like 1200 / 1400 for a while and then drop off back to 800/900

my first thought was IAV but i'm pretty sure there are a bunch of things that can f**k with idle,

has anyone has this problem in particular when backing off?

thanks

[LTHLRB]

have you got an aftermarket bov? it sounds like a vac leak somewhere

if your iac valve was shagged it wouldnt idle and just hunt flat out. once you back off the car will just die on the spot.

[mystery_kid]

yeah i have an aftermarket bov but it has never been a problem until recently

sometimes when it's playing games with me i can just rev the tits out of it in neutral to like redline and it will make it go away for a while, i do that when it's being really annoying

[34GeeTeeTee]

yeah i have an aftermarket bov but it has never been a problem until recently

sometimes when it's playing games with me i can just rev the tits out of it in neutral to like redline and it will make it go away for a while, i do that when it's being really annoying

Suspect a vac leak or BOV issue...

[LTHLRB]

Plumb back or atmo bov?

[mystery_kid]

it is an atmo bov, it was like that when i bought the car and all the inlet piping is custom from the throttle body to the intercooler so swapping back to stock is kind of out of the question

regardless i've never had any of the problems others have with atmo bov's and stalling

i think i will change all my vacuum hoses, i'm over the tacky blue ones the car came with anyway

[Ben C34]

So did it ever run nicely with the atmo bov?

That's very likely the problem, and at the least is part of the problem.

[mystery_kid]

yeh it's been fine since i bought the car back in 2011 up until earlier this year

[mystery_kid]

in saying that maybe i will investigate plumbing it back, just to be on the safe side

[34GeeTeeTee]

in saying that maybe i will investigate plumbing it back, just to be on the safe side

Its not going to hurt! My GTT hated the atmo one when i had the stealth GFB thing on it, i had to rotate it until it was basically plumb back to get rid of the issue due to the reversion etc!

[mystery_kid]

so an update, i finally go around to changing all of the vacuum hoses which was fine. changed out shitty looking blue silicon ones puts on by a previous owner at some point for black rubber ones

long story short, hasn't made any difference at all

in the past couple of weeks once it gets to the temperature where it all starts to back off and idle shit the TCS / Slip lights have been coming on sometimes and even when i am backing off down a hill the engine light comes on sometimes, when i get back on the power the engine light will turn off again. to be clear the coil packs are fine they are aftermarket items i put in myself a couple of years ago after i bought the car, it runs fine under power there is no missing. those lights can come on sometimes when i'm not even moving at a set of lights

could it be something like the AFM?

Edited October 19, 2014 by mystery_kid

[mystery_kid]

it runs really nice when it's cold, nicer now that i've changed all the vac hoses. when i finished fixing it yesterday i let it warm right up and then i took it for drive around giving it a good squirt and it was fine

i drive to work this morning which is only a 10 - 15 minute drive and like clockwork at around 65º~ it just starts being a flamin mongrel when i back off, idling high etc

[mystery_kid]

did a bit more research, it is sounding like my TPS could be the issue