# Hissing from around PCV stuff 2.0 aeg



## AbuNigel (Jul 11, 2009)

I have been having a bouncy idle and chronic CEL for quite some time now.

I have a cracked coilpack that needs to be replaced and with that i'm going to do spark plugs and wires as well. I replaced all that stuff less than a year ago but just went to pepboys for everything so sure enough the coilpack crapped out on me and i don't particularly trust the wires either. Back on my old cracked for now but like i said i plan to refresh all that stuff with good quality parts soon.

That said, i've also been dealing with another trouble area that i think could be contributing to my car's illness.

I noticed there is a good amount of oil/grime around the heating element at the joint of the pcv breather tube and the throttle body intake tube that comes right after the maf.

There is also oil on my valve cover.

Also, i have noticed a slight hissing noise from around the pcv breather tube area.

So i just ordered and replaced the oil filler cap, the pcv check valve, the pcv breather tube, and the line that goes from the throttle body back to the pre-throttle body intake tube, right below the main breather tube, where the heating element is.

Before i replace that thinner line i noticed it seemed cracked and when i covered that area the hissing seemed to stop.

However i put new line in, but the hissing persists. It goes away when i squeeze that line though.

I'm not sure if this hissing noise is just a noise the pcv system makes normally, or if there is a leak somewhere i still haven't found. Could the joint with the heating element, where the breather tube and that thinner line meet the intake tube be faulty? Could the oil on and around it be an indicator of that? 

I hope not, that intake tube is like a 200$ tube if i recall correctly : /

In addition, i'm noticing a lot of oil that seems to be leaking from my valve cover. Not sure if that is related to anything or not.

Pic of said joint right before the throttle body.


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## Vwsythe1 (Feb 8, 2009)

i have the same problem with the hissing sound that comes from the area you speak of. but i found that my brakebooster vacuum line is damaged so that may be it.


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## Anony00GT (Mar 6, 2002)

Hard to say without hearing the noise.

What fault codes do you have, if any? Do you have access to any scan tools? A vacuum leak will show in lambda (fuel trim) data.


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## AbuNigel (Jul 11, 2009)

I have to get an up to date read on my codes. No scan tools available atm but i could potentially looks for someone in the area.

The times i've scanned i often got bank # system lean and that kind of thing, along with others like misfires, maybe an o2 sensor one as well.

I'm pretty sure my valve cover gasket is well over due to be replace. There is a good amount of grime around all the cylinder holes and i'm wondering if that could be affecting my ignition performance.

I figure i'll replace that gasket along with the intake manifold one and change spark plugs wires and the coil pack all in one go, since i think that stuff needs to be handled regardless.

I'd like to check my maf condition and clean it as well but it's in with the most ridiculous, 5 point star with a security center screws. Got them out with vise grips once but it wasn't fun...

Anyway, i'll check my codes tomorrow.


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## AbuNigel (Jul 11, 2009)

So i scanned for codes earlier, but I'm going to wait to see what comes back before I post up, because I think some came from my troubleshooting.

That said, I was listening for the location of the hissing just now and i'm pretty puzzled.

Like I said, when i squeeze the line that goes from the tb back to the inlet pipe the hissing stops. But considering I just replaced that line I feel like the leak has to be coming from the inlet pipe itself, possibly just the joint where the two pcv lines and the heating element attach. That would make sense as to why it has a lot of oil around it. I'll remove it when I get the chance and do a thorough inspection with it off the car. 

What doesn't makes sense to me though is that if that air inlet tube has a crack or leak why would it seemingly stop when i squeeze this one line? It still has air/vapor moving through it via the air intake and maf, and the pcv breather tube that comes from the valve cover. So why does the hissing stop when just one of these three inputs is restricted?

Is the line that cycles air back through the tb much higher pressure than these other sources?


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## AbuNigel (Jul 11, 2009)

After driving a little while CEL came back on, I scanned and then cleared the one code right away. All I got was a P0134.

Maybe my 02 sensor is bad?

Of course idk what that would have to do with the hissing issue, but maybe that in addition to my worn out coil pack could be the cause of my shakey idle. I think the shake is worse once the car has been running for a little while. It may just be my imagination, but I find it to be the worst when I come to a stop right after getting off the highway, like at the off ramp. I'm assuming my engine is particularly hot after highway driving so maybe that is a clue into this.


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## AbuNigel (Jul 11, 2009)

So after a little over a day my CEL came back, just scanned it and got a p1128 and p0134.

That's the second time I got the p0134 as an initial code so the idea that my front o2 sensor needs to be replaced is seeming more likely.

Also I'm finding that on cold starts it doesn't fire up quite as quickly as it should. I think this is my coilpack on it's last legs.

As I mentioned before I intend to change the valve cover gasket, along with the intake mani gasket, spark plugs, wires, and the coil pack. Maybe my old coilpack is the sole culprit of my shaky idle, although I don't have my hopes up.

I want to get the block rid of all the old oil and grime that has accumulated around the cylinder openings when I do this. Any tips for doing this safely without getting dirt in any open engine cavities? I was wondering if I can use a degreaser and compressed air to clean it with all the components still put together, maybe remove the plug wires for more access. Is there a proper way to do this? Last time I was changing spark plugs I was struggling feeling for the threads not to scratch any grime into the cylinder holes. If I'm gonna have the intake manifold and valve cover off to replaced gaskets and all, I want to clean as much as I can and do a seamless plug install while I have the chance..


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## Anony00GT (Mar 6, 2002)

P0134 is no activity B1S1, P1128 is lean multiplicative.

Fix whatever vacuum leaks you've got (hard to help there without physically seeing the car), then re-evaluate the O2 sensor and check the MAF.

Have you done any diagnostics on the coil or are you just assuming it's bad? (Didn't you have another thread not too long ago about replacing your coil?) Fix the fuel trim issues, then see how it runs before going after ignition components.


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## AbuNigel (Jul 11, 2009)

well I have inspected it and it's got quite a few cracks. It will have misfires issues occasionally after rain or moist spells.

You're correct about a previous thread. It was about swapping in a new coil pack and having cold start misfires only a month after. The cylinder 1 plug post was failing and not making a proper connection with the cylinder 1 wire. The problem went away when I put my old cracked coilpack in. This was due to it being a crappy pepboys bought brand, I'm quite sure.

My plugs are 3 prong bosch platinum i believe and my plugs are pro start brand, or something like that. Neither are ideal from what I hear so I figured replacing all that stuff with good quality parts from GAP would be a smart move regardless. But is it not?

This could be way off the mark, but I've been suspicious that inadequacies in my ignition system could be contributing to unburned fuel etc. and possibly be the root cause of my fuel trim issues. That might not be how this stuff works though...Still learning!

I'll pull a spark plug today and see the condition. I checked one a while back and it was black (carbon fouled, i believe?) Which would lead me to believe something isn't igniting properly. That might have been back when i had the pepboys coilpack in and had the regular misfiring, so like I said I'll check again to see how everything looks.

Today I'm going to swap the intake tube (between the maf and tb) in from my friend's 2.0 to see if that fixes the hiss. I might try swapping his maf in as well to see if that helps anything.

I'll also search around for vacuum leaks although to be honest I'm not particularly confident in my ability to identify those..


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## AbuNigel (Jul 11, 2009)

I also intend to change the fuel filter.


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## AbuNigel (Jul 11, 2009)

So i put in a new valve cover and intake manifold gaskets, cleaned up the block and installed the new and oem plugs, wires, and coilpack. It does feel smoother but the hiss, shaky idle, and codes (p0134, p1128, and one other) are persisting. I didn't expect this latest maintenance to fix though, but it would have been nice..

While everything was apart i also inspected the throttle body inlet intake pipe and saw no abnormalities on the inner walls, and i finally found the special bit and was able to take out and clean my maf. It looked perfectly clean to begin with though...

I was able to give a general look over of the 2 vacuum lines that are at the rear drivers side of the engine bay and nothing looked out of wack.

I used a paper towel tube to try and better hear the intake hiss' location. It seems to be coming from the tb-back-to-intake-pipe line, right near the input barb for the air line that connects to the fuel rail.

But it still holds true that, if i squeeze the line that comes off of the tb and goes back to the intake pipe the hiss goes away.

But this is newly replaced line and the hiss was there before i replaced it when it was an oem line with a one use clamp as well, so i don't feel like it is an issue of clamping quality.

I'm clueless... But i'd like to think that a leak of some kind in this intake pipe could be the source of my fuel trim issues and if i find it maybe everything will be solved. But i can't know if that has any truth or not if i can figure out where this stupid hiss is coming from!!!!!


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## Anony00GT (Mar 6, 2002)

P1128 is lean multi, probably not a vacuum leak. A bad O2 sensor (P0134) could cause this though. What kind of scan tool are you using, and does it have data capability?

Make sure the wires and connections to the O2 sensors are good and tight. If so, replace the upstream O2 sensor, direct-fit Bosch or OE from the dealer only. Then re-test.

I think the hissing might be normal, not sure without hearing it.


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## AbuNigel (Jul 11, 2009)

Yea i've been thinking of just replacing the front o2 sensor.

All i have available right now is a 15$ code scanner, no data reading.

Would a bad front o2 sensor be a logical cause for the shaky idle though?

Another bit of info is, paying closer attention lately i find the shake is at its worst when the engine is very hot. I think it's completely absent when the secondary air pump is doing its thing. But when i come to a red light at a highway off ramp or something where i come to a stop from long continuous throttle, between 3k and 4k rpms, the shake is noticably worse.

I got that third code i mentioned before last night, it's a p0422.

So a mix of p1128, p0134, and p0422.


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## lazylu (Sep 17, 2010)

Mine was also brake booster tube

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## AbuNigel (Jul 11, 2009)

lazylu said:


> Mine was also brake booster tube
> 
> Sent from my LG-P925 using Tapatalk 2


But would that be affected by pinching the line from the tb to the intake pipe?


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## lazylu (Sep 17, 2010)

No the brake booster line is near the wall of engine on driver side

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