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-   -   DASC Smog Failure, what does PCV do? (http://www.318ti.org/forum/showthread.php?t=39271)

Artem 10-15-2013 12:57 AM

DASC Smog Failure, what does PCV do?
Hey guys,

Failed smog today, prematurely before the inspection deadline to get it fixed by then. HC/CO were totally fine, so I am suspecting a good cat/O2. My intake system is all sorts of screwed though.

As a result, I want to sort out all/any possible air leaks going on in the engine, and I will machine an ICV/TB combination for that.

However, for the final leak detection - What does the crank case valve do? I want to replace it as I do not like the stock DASC method of sealing it, and I want to know its specification to find a suitable replacement for it possibly one with built-in nipples for easy attachment of hoses.


PS - did any one of you ever have a misfire issue with the COP conversion? Mine throws a code on 4th cylinder and I am wondering what it can be or whether I should just throw a different coil in there? I got plenty of spares.

pdxmotorhead 10-15-2013 07:34 AM

Use a standard Chevy PCV valve and a hose to the inlet side of the blower.. Done..
Its typically a one way check valve that allows a vacume to be built in the crank case.


Artem 10-15-2013 07:45 AM

Thanks Dave!! Much appreciated advice, I'll grab one at Kragen or something.

New throttle body coming in tomorrow, going to try and drill + tap vacuum fittings in there as-is and see how big of a hose I can put on there, that should sort out the idling issue.

pdxmotorhead 10-15-2013 07:50 AM

There are a couple,, but the one you want is a early style chevy that pushes into the rubber grommet on the chev valve cover.. You should be able to either use the exisiting hose connection, or add a hole and use the GM grommet.. Works on most race cars.. :)


Artem 10-15-2013 08:09 AM

1 Attachment(s)
Awesome, sounds like a plan. I will use that one, hoping to attach the PCV directly to the valvecover and the DASC intake elbow.

So far I was able to machine a sweet Ti piece for the smog pump (attached, braggin rights). But it did take a couple hours of turning it and milling it, so I am hoping to avoid that in the future - so trying to get 'off the shelf' parts.

Artem 10-21-2013 05:34 AM

ICV Description + ICV Relocate plates
5 Attachment(s)
Hey everyone (whoever's reading this thread) - I got some progress, great IDLE now, with TB fully closed, misfire all around, tons of CEL codes thrown, going to have to do something about all of that, but in the meantime - here are some progress pics with info.

I had 2 spare ICVs so I took them apart, and I realized that most of the used ones are most likely not good (read - crap). Most common failure is the O-ring on the ICV which is in the middle of it. Attached are pictures of me machining the idle control relocation plates and pieces of the ICV.

ICV is basically a weird looking shutter with pretty tight tolerances. The plastic housing is a two-part piece and one of them (one with an electrical connector on it) houses the electromagnetic piece which has two positions, open wide (cold start) and open partially (normal warm idle). The TB is fully shut during normal operation and ICV lets the air pass.

The second plastic housing piece has a press-fit and molded over shaft which has two grooves in it which are equidistant from both edges of it (Im guessing for simpler manufacturing). The main shutter element is a rare earth magnet which is epoxied or plastic molded together with the L-shaped metallic piece that actually acts as a barrier for airflow. And there is a tiny roller bearing press fit into the metallic side of it, which has a washer between the plastic housing and the bearing.

Now - the two plastic housing pieces are connected together using a bayonet type connection with a special groove for a sealing o-ring in between the two. There is a metal bushing that is likely heated and pressed to lock the two halves of the ICV connector in place. All 3 ICVs that I have (2 spares and one on the car) had bad O-rings, which is typical - the rubber hardens and it's typically a relatively high pressure differential area where the engine always wants to suck air in, so over time air passes through along with all the dirt and oxidizes the stuff inside, which is no good. Best course of action if an ICV is giving you problems is to take it apart, clean it out with IPA or something similar that takes most of the rust off, and reseal using a new O-ring, preferably covered in vacuum grease. (I believe the O-ring size is 27mm X 2mm, but I will check by trying some in there, didnt buy a replacement yet).

Oh and forgot the most annoying thing - there is a wave spring that keeps the two halves under pressure against each other so that it doesnt rattle around, so watch out for it. Kind of annoying when the magnet wants to attract it, as it is fairly basic steel. Overall a very nice design for a basic part that all cars use, one of the more complicated ones that i've seen so far.

Just sharing some info with the group :)

Artem 10-21-2013 05:49 AM

Oh and also - does anyone know where I can get 1/2" and 3/4" hose that doesnt kink? Its fairly relevant to my smog pump and idle control woes.

hodge 10-28-2013 01:25 AM

Great work!

So you are making your own ICV relocation adapters for the DASC? Would you be willing to make more of those? Im debating keeping my DASC kit (which is on an M42) and putting it in my wife's ti (which is an M44) and I know the ICV needs to be relocated. I haven't called Downing yet to see if they happen to have any laying around. I have no way of making my own.

Shoot me a PM!

Artem 11-14-2013 12:29 AM

Hey thanks guys. Good talking to you earlier, Tyler!

I got an odd thing now, no CEL, but computer keeps on saying its not ready. I scanned the codes with my OBDII scanner and it comes up at P1174, which means a disagreement between a real fuel/air mix and an expected ratio based on a fuel map. I am trying to figure out what the hell is going on - going to try taping all the possible leaks and throw that old school chevy PCV valve in there (already bought a couple).

Having said that, I'm trying to understand why it is not throwing an actual light when its getting a P1174 code and its flashing red on my reader. Is there anyway to force the computer to get ready? I am convinced that the tailpipe emissions are good now that all the work is complete - I just want to get the reading from the sniffer and call it good (since all the emissions components are in place, operating as they should and my cat is good). I need a pass in december so I can re-register it.

pdxmotorhead 11-15-2013 08:46 AM

did you disconnect the power from the car and let it sit then reconnect yet?

ECU may just need reset..


Artem 11-15-2013 08:59 AM

Naa, I used a reader to reset it, I'll try disconnecting tomorrow. Good call, thanks!


hodge 11-15-2013 04:24 PM

Good talking to you too Artem.

Like PDX said, try disconnecting the battery for a half hour or so, so it clears. I need to try that on the ti too.

Artem 11-16-2013 05:24 AM

Hello again guys,

so that disconnecting thing must have done the trick, because right after disconnecting and leaving it alone for a while, when I reconnected the battery it started running like crap. I cleaned that MAF and replaced the intake boot with a silicone unit that I cut up out of a long right angle piece to try and see if that helped, and it didnt, not much of an improvement. The ICV lines arent blocked or kinked and it was idling pretty much perfectly right when i parked it before disconnecting the battery. The only possible thing I can think of is the damn PCV that I still havent replaced - Im using a 'replica' of a DASC adapter and a stock pancake CCV, which may be leaking.

For now what happens is every time I come off the throttle it just runs the revs up and down from what it feels like its about to stall out to 1000+ RPM and back down in an oscillatory fashion.

What Im suspecting is a vacuum leak between the MAF and the engine, Im not sure if it would be after the throttle body or before it, although I did just replace a boot in there, so...

Anyway, would be interesting to see if anyone ever experienced a similar issue.

I'll try to come up with some sort of a crank case system in the meantime. What is this catch that everyone speaks of when putting another valve in there? or does it even need a one way valve if theres a catch can?

pdxmotorhead 11-16-2013 08:36 AM

look for things that would change th eair volume between the meter and the throttle body. When the boot cracks on my 95 it raises hell with the way it runs. Any vacume leak on the thing will..


Artem 11-19-2013 07:11 AM

GUYS! AWESOME!! Dave, you're a life saver!! I threw that standard PCV in there and that seems to have done the trick, I dont know if it will not throw codes for sure, but the oscillation and hesitating is GONE!! I used a standard chevy PCV 348 for reference, just stuck it in there, trimmed some hoses so that it would be tighter and put some clamps on it, it worked great!


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