Why does my Intake Air Control Valve keep on failing? - Page 3

93specv · 05-10-2009, 10:53 PM

idle frustration accross the country!!! oh man. searching i found this thread, a few things stand out to me, most suggestions ive already done. i have realtime, conzult, bla bla...must go to bed though. 4am comes early! i will be back! upcoming questions will include: no cold idle, MBC has no effect on boost psi, and no idle with BOV vac to IM. only idles to the TB. i will be back to pick brains!

93specv · 05-12-2009, 12:02 AM

in scratching my head tonight, i realized im boosting my crankcase. i have the widely discussed shooting dipstick issue. i will start there 2mrw on my day off. another something to inquire is pcv....delete? or reroute to another source of air? my buddy suggested running the hose to the intake before the turbo. also, my tial wastegate is routed to the pvc hoses. that will be changed tomorrow along with the air regulator. i too tonight attempted adjusting the idle with the screw on the valve near the oil filter. warmed up, i put it in timing mode in conzult, unplugged the tps and "screwed" around. the idle did nothing different. another thing is i have a breeather on the valve cover instead of routed to the intake before the turbo. to my understanding though, that would affect idle at all temps, not just cold.....?

mindmineral · 05-12-2009, 05:53 AM

THANK GOD!

!! FIXED !!

goneturbo
Thank you for all help but it was something which I should have clocked onto time ago!

Solution
Longer pipe between turbo and MAF.

The MAF has a sensor in there to detect temperature. As the MAF was too close to the turbo - it was picking up the heat from the exhaust. Upon deceleration it didnt have enough cold air so the engine would keep on plumeting till it found enough cold air - at which point went way too far below base idle causing the engine stall.

I tried this solution when i first got the car and completely forgot I did this.
Thanks to all those that helped - I hope this post helps others.

Peace

93specv · 05-12-2009, 03:08 PM

seems to idle cold now. i have to wait to cool down and try again later. routed WG to intake mani, ran hose from VC to intake before turbo after MAF (draw setup) and switched air regulators under intake runners. also bumped my cold timing from 15 to 17 in tunerpro. seems to like it. seems i lost a couple lbs of boost though. not really sure, i didnt really get to open it up. unfortunaletly doing multiple things at once, im not sure exactly what fixed my cold idle...but then again, we'll see in a few hours if it didnt just magically unfix itself. i also found a slight boost/vac leak. so we'll see whats up later with the cold idle, and get it on the highway and open her up. if all goes well, i will tee the MBC back on and see if it works now.

although, adjusting the idle with the screw, and/or in tunerpro still has zero effect on my idle. only way to adjust my idle is with the throttle cable itself. theories?

93specv · 05-12-2009, 07:56 PM

WTF!!!!!!!!
nope, no cold idle still. just got home to try and nothing. SIGH!

93specv · 05-31-2009, 12:12 PM

horaay for me! problem solved! IACV! i swapped it with the old dirty, grimey, sludgey, crappy ass one from my old motor...idled as soon as i turned the key! the old saying: if it aint broke dont fix it holds true here. when building my motor, i "cleaned" the IACV that i just swapped out. apparently in "cleaning" it, i did more harm than good. there was a little smoke on initial fire from the build-up burning off. but after that, she runs awesome now! im stoked! cross another one off the list!

93specv · 06-18-2009, 11:39 AM

problems persists!!!!! it came back only a couple days later. new theory is i am not running an oil catch can. the blow by may be clogging my iacv? i was planning on caleaning the rusty pos, re-painting, and reinstalling...just never got around to it and didnt see any problems in not doing so. well, maybe this is one major issue! hopefully it works. im running outta ideas.

I_Like_Hardware · 09-04-2010, 08:16 AM

I don't mean to bring back an old thread, but I recently had the same issue with the dive-bombing idle after downshifting and the stuttering from 2k rpms - 3.5k rpms.

My current fix for the diving idle was swapping out an IACV from another vehicle(I mainly did this because the idle adjust screw on mine was frozen and I stripped the head). However, after I did swap the IACV, I ended up having an abnormally high idle, (even when I set the idle during base timing mode, which is when you set it I believe?) which would slowly go from ~1400 to 1000 and then down to ~800rpms when sitting at neutral.

So how I fixed the idle was, in-part, helped by this thread. I took the advice in spraying down the EGR line from the header where it connects to the BPT valve. But there was one other thing I noticed, and I'm not sure if this is vital... or if it just got wedged in there somehow, but there was a small piece of metal that was mid-way in the hose from the BPT to the hard-line. I removed the peice(more or less the hose just fell apart...fail

) and robbed a hose off another motor. I'd get a picture of it, but it's too small for my crappy phone camera.

In addition to that, I shut the car off and backed the idle screw most of the way out and started the car again to go back into timing mode. When I did that I could get it down to the right rpms so I could time it.

Whatever that little metal thinger was, it was doing something that wasn't good. Since then I now don't have stuttering! My only hope is that it stays this way.

I just want to know what that metal piece was now!

Also, sorry if this doesn't make sense. It's 7am, I'm feelin' a little stupid.

goneturbo · 09-04-2010, 09:06 PM

Cleaning or replacing the EGR valve and tubing, does wonders on these engines for studders and idle issues. I am not sure what a plug on the BPT may do to performance.

Getting a highport into timing mode is near impossible, I have always needed to use a laptop and a conzult interface and program to set my idle. I'd recommend the conzult setup if you continue to have issues or have to smog the car at any point.

I_Like_Hardware · 09-06-2010, 08:09 AM

I've had no problems with getting into timing mode, so far as I know. I've set timing multiple times with no issues and set idle speed as well now.

However, I notice I have a very slow idle drop down: Rev up and drop off, rpms drop to about 1500 for a second, then sit at 1100 for a while(~10s-15s), and then after that it will finally drop to around ~850.

Then there's a whole other deal with my car, which is why it takes forever to reach operating temperature, which also affects the idle. Unless my car is completely warmed up, my idle won't drop below 1k rpms.

Luckily this won't be my winter car. Takes about 20 mins just to hit C on the temp guage. Will also drop below C if I drive at all. ._.