How to fix your stock PCV system and intake manifold

[mja]

Last week I was getting on the freeway. I heard an audible pop-poof and lost boost. After resetting the ECU, boost came back and all was well. Until a few days later when I threw these codes:

P0238
P1101
P2227

Indicating an air leak or vacuum leak. So I pulled the charge pipe off the throttle body, and oil was in the charge tubes. Knowing exactly what the problem is, I pulled the stock manifold and found this gem:

Another blown check valve :blankface:

I wasn't ready for the swap, didn't have all my parts for this modified manifold, so I had to rush the job and jerry-rig it.

Crank runner to the Subaru WRX PCV valve:

T-connector to the BPV solenoid vac source (this will be re-routed from a vacuum canister when parts come in)

Manifold tap to PCV inlet:

Had to make-do with the connectors and zip-ties I had since I didn't want to run a blown check-valve manifold. All codes are gone now except for a P0033 code, comes on under boost and triggers limp mode to limit boost to 6-8psi. This limp mode is standard when the BPV solenoid code is thrown.

This code is because I have the vacuum line to the BPV coming from crankcase vacuum (weak vac source at WOT), instead of a dedicated vacuum tank like the stock application (strong vac source under WOT).

Summit unfortunately back-ordered the AC-Delco S-10 vacuum tank, so I cancelled it and ordered the Dorman part # from Amazon. Should be in on Dec. 30th. Will route the proper vacuum source to the BPV, correct sized connectors, and hose clamps to clean this thing up. Once all is well without codes, I'll be checking vacuum at various locations and post the numbers here.

 

[mja]

A note about oil catch cans (OCC) as a bandaid to this problem. OCC won't help when the check valve blows. They are designed to baffle oil under crankcase vacuum conditions. When boost sees the crankcase, it blows out oil from the crankcase through the OCC. Mine only had a small amount in it when the check valve blew, and a lot of oil in the charge tubes.

 

[mja]

Final step:

Here you can see the 1/4" hose that goes from the crankcase 'T' to the input side of the S10 dorman vacuum check valve (top left)

The smaller hose runs from the strong vac/dorman vac. 'T' check valve output, to the BPV solenoid (bottom right)

There was enough room under the cowl to add some plastic screws and bolt it in. I also ran a 3/8" barb krankvent ahead of the PCV, it's the shiny valve to the left of the vacuum canister.

This picture shows it all buttoned up with the Dorman check valve installed.

Edit - when running vacuum lines, make sure they're away from heat sources, and don't leave so much slack in the lines that they could kink over time.

Good news, bad news. The good news is the thing runs like a bat out of hell. The bad news is I'm getting an intermittent BPV solenoid code which cuts back into limp-mode. Restarting the car/resetting the ECU clears this limp mode and it runs fine again.

The problem: the Dorman check valve. This is a cheap piece. When I blow into the vacuum check valve, it sometimes closes the valve and sometimes does not. That equates to the canister sometimes being under strong vac, and sometimes crankcase vac. This must be where the intermittent code is coming from as the BPV solenoid doesn't get consistent strong vac from the canister to BPV solenoid.

I'll try the cheap fix - replace the Dorman 47150 with the AC Delco 15-50568. Even this AC Delco valve has poor reviews (maybe why the S10's HVAC controls suck so much).

I may have to end up getting an older style vacuum canister with an inlet and outlet, like a Dorman 47076 and run a simple one way vacuum check valve into the canister, and line out to the BPV solenoid. This would help with consistency/reliability. Will keep this thread updated when parts come in.

 

[Llia]

Wouldn't a vacuum Tee between the check valve and the canister be the same as two ports on the same canister?

 

[mja]

Wouldn't a vacuum Tee between the check valve and the canister be the same as two ports on the same canister?

That's correct Llia. The T-vacuum check valve isnt the best. At least the Dorman one isn't. My thought was an inline check valve would be simpler and more reliable.


Update - it seems the ECU has relearned my setup even with the Dorman check valve. I have had no codes for 2 days. Hopefully it's not just due to the cold weather (got below freezing finally in Houston). I'll install the AC Delco check valve and it should be good to go.

 

[mja]

Week update - There were no codes after the ECU relearned with the Dorman check valve for 3-4 days. Then, I threw some codes. Replaced the Dorman with the AC Delco check valve, this valve functions much better from the blow-through test.

This time I reset the codes manually instead of having the ECU learn, and will update in the next few days to share how it's doing. Car seems to be running fine right now on a few engine cycles.

BTW - the vacuum tank listed in above posts, with the 2-line in & out, is much smaller, maybe half the size of the S10 vacuum tank and about the same size as our stock air bladders supplying the BPV. I will change out to this smaller one once I get the current t-valve setup working, so hopefully people can see multiple options.

 

[mja]

Changed to the AC Delco vacuum T valve, and it runs alright. I'm getting a P0238 code and intermittent P2261.

This tells me I may have a boost leak somewhere. Will pull the manifold in a week or so to check it out.

In the meantime, I'll swap out to the smaller vacuum tank and straight-through vacuum check valve. (Edit - got the car running right, so I'm in no hurry to swap out to the smaller vacuum tank)

 

[mja]

Found the issue which was causing the P0238 code.

This 5/8" vacuum hose was kinking (the one in the top left, goes from underneath manifold to the oil catch can, actually a heater hose vs the old fuel hose I used to have on there), simulating a clogged or stuck PCV valve. Tied up the hose and it runs like a champ without codes.

Re-simulated the kink just to make sure, and the same P0238 code was thrown. Will be replacing the majority of this heater hose with either pipe or braided fuel line in the future.

 

[Blue Moon Sonic]

This thread should be a sticky. This whole thing idea could be made into a mold for a cast aluminum intake manifold with the revised PCV routing. Just make sure to have a thermal coating to act as a heat barrier.

 

[greg51]

Hose-5/8"

You can use an inner hose coil support. Earls Performance stainless coil goes inside hose so it does not collapse on suction . Its like $10 from Summit, -10 size fits inside 5/8" hose. greg

 

[Llia]

I found some aluminum 5/8" tube on amazon. I picked some up for my catch can and some 5/8" compression fittings to 1/2 NPT that I can connect a brass barbed fitting to.

 

[tainopayute]

I found some aluminum 5/8" tube on amazon. I picked some up for my catch can and some 5/8" compression fittings to 1/2 NPT that I can connect a brass barbed fitting to.

Can you post a link?

Sent from my SM-G920T using Tapatalk

 

[Llia]

Can you post a link?

Allstar ALL40186 5/8" Diameter 25' Aluminum Coiled Tubing Fuel Line

 

[tainopayute]

Allstar ALL40186 5/8" Diameter 25' Aluminum Coiled Tubing Fuel Line

Thanks for posting the link. I had to copy and paste it on the amazon search bar because it didn't want to open for me but I saw the tubing that you were talking about. [emoji106]

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[Blue Moon Sonic]

I actually am just using 3/8 transmission line to connect the corrugated tubing to my catch can and loop back to the turbo inlet. Doesn't collapse like heater hose.

There could be a simpler way to fix the PCV check valve issue where you just get a one way check valve and run it inline with the PCV line from the manifold to the turbo inlet. Now if you are running a catch can, You may not even have to run a PCV check valve at all. I know with VW 2.0L FSI engines running a catch can or a front PCV block off plate plate, you can actually remove the check valves from the system entirely with no adverse affects.

 

[greg51]

pcv

there already is a check valve in the 5/8" line to the turbo, you will notice its made of stiff plastic tube--does not crush like hose. When i hooked my oil catch up when the motor was idling it would suck the heater hose flat, was worried that after time it would stay that way thats why i put the Earls coil inside mine 5/8 hose. g

 

[mja]

there already is a check valve in the 5/8" line to the turbo, you will notice its made of stiff plastic tube--does not crush like hose. When i hooked my oil catch up when the motor was idling it would suck the heater hose flat, was worried that after time it would stay that way thats why i put the Earls coil inside mine 5/8 hose. g

That is not a PCV valve. That hose houses a valve at the inlet of the turbo, a check valve. The PCV valve is necessary or the engine won't operate correctly.

Update - I tried to re-route piping to take care of the high speed kink/restriction that was developing, if too many 90 deg. bends are present then not enough vacuum is present. Will go back to the old setup shown here in the thread...without the WRX PCV valve, and just usethe krankvent (PCV) valve. Also, there is little difference from the through-style vac. tank vs the single inlet. Just use the correct straight through vs vacuum fitting.

I noticed a thread on the cruze forums after posting this which uses the throttle body spacer instead of tapping the manifold for manifold vac source. Either design will work, however the cruze mod doesn't address the BPV vacuum tank check valve and gunking up the BPV solenoid line with oil over time.

 

[mja]

There could be a simpler way to fix the PCV check valve issue where you just get a one way check valve and run it inline with the PCV line from the manifold to the turbo inlet. Now if you are running a catch can, You may not even have to run a PCV check valve at all. I know with VW 2.0L FSI engines running a catch can or a front PCV block off plate plate, you can actually remove the check valves from the system entirely with no adverse affects.

I wish that were the case. Unfortunately our intake manifolds have a chamber which connects the intake mani vac/boost source through the runner into the head. This is where the PCV valve/poppet is located. It seems many members overlook this in relating the system to a traditional external PCV system.

 

[Blue Moon Sonic]

I wish that were the case. Unfortunately our intake manifolds have a chamber which connects the intake mani vac/boost source through the runner into the head. This is where the PCV valve/poppet is located. It seems many members overlook this in relating the system to a traditional external PCV system.

That is why you have it routed the way you have it. You are right too With a normal PCV system. Normally, one could do a VTA (vent to atmosphere) setup where the PCV contents just get dumped and the car wouldn't mind at all. You try and do the same thing on the sonic and the car acts like it wants to die all the time because of the lack of vacuum.

Still say when you have the finalized product and testing is done, Have it made into a mold to make an aluminum Intake manifold without the runner flaps. Pretty sure there was demand for them at one point in time.

 

[mja]

I'd really love to have an aluminum version of this thing. Something reliable that makes more power would be awesome.

Update - turns out my codes weren't from the modified manifold at all. I was throwing a p0106 & p0107 and couldnt track it down for the longest time. I checked everything and was so frustrated thinking it was a vacuum leak or restriction, so bought a new stock manifold to try. Nothing, same codes.

So I started checking the wiring and came up short in voltage in one of the wires supplying the MAP sensor. I knew my MAP sensors are good, I have like 3 of them. The wire was cut halfway inside the actual plug, so had to rip the wire out and cut up the plug to solder in a new section. All is well now and Turbo is back online. Will reinstall the modded manifold soon and get the final update on this manifold madness .....finally.