93 Honda Civic VX horrible fuel economy

[benfrogg]

Well, I'll investigate the car later tonight. I'll follow the whole line from crankcase to IM and get back to you.

The diagram shows #16 and #6 as though they were similar parts for the same location. Perhaps year to year they used one set and another in another year. #16 looks exactly like #2, #15 looks exactly like #6.

I've had a pcv valve in this location before. I replaced it with the stock elbow after about 500 miles. I noticed no significant change in FE or how the engine runs.
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[theholycow]

Originally Posted by *************

no no no! That's not how the PCV system works! Did you buy that Buick new or used? The guy at the autoparts store tried doing the same thing to me! He tried to sell me an elbow instead of a PCV valve!!! I told him that an elbow is not a PCV valve and then he brought out a PCV valve instead. I think there is a serious issue of people not understanding the purpose of the PCV valve and so are replacing them with elbows..

Nobody had any record of a PCV valve to sell me. I finally found some info (in the car's manual, that should be the final word, I'd think) and special-ordered the PCV valve. It doesn't fit the hole where the elbow plugs in, nor does it fit the elbow.

My grandfather bought it new but in the 25 years before I ended up with it I can't say what kind of maintenance was done. With only 35,000 miles by then, there's a good chance nobody ever touched the PCV system. The elbow was covered in a thick layer of grime and appeared to never have been disturbed.

I wanted to put one in but I don't think one exists.

[benfrogg]

Don't I hate being wrong...
So, look at the image from majestic. #2 which is not listed in the list but is in the diagram.


This is a straight one way valve. It has a very weak spring inside. Mine was nasty before I cleaned it. It has p07 in the part number, so it's factory.
The green part is the one way side of the valve. It lets pressure out of the crankcase and into the IM. Before cleaning, mine let air into the IM but didn't keep it all from going the other way. We'll see if this changes anything.

So, *************, you win!
This valve is buried deep under the IM going into the breather box.
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[benfrogg]

HC-
Look for a straight union type piece in your Buick. This one looked like just a barbed plastic piece to get into the breather box. Turns out it houses inards. Maybe your idle issues are related to this part!
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[add|ct]

Wait wait wait...guys...is there some sort of place where an ACTUAL PCV "VALVE" is, and the thing we THOUGHT was the "VALVE" was actually just an elbow the entire time?!

ADDED: Okay from the manual on "Maintenance Schedule"

Every 60k miles "Inspect" Positive Crankcase Ventilation Valve"

How to determine?: If clicking sound is heard as you pinch the PCV hose between the PCV valve and intake manifold, valve is OK.


Is it alongside the runners at another rubber hose, then ben?

Also, what is your take on items 15 and 16 from the Honda Automotive Parts site in the diagram? For other models of the Civic?

[benfrogg]

addlct-
It's located under the IM. In the picture, it's number 2 which plugs into the breather. Follow the hose from the 90 we though was the pcv. If you reach under the 90 you can feel the hose headed towards the passenger side of the block. At the end of the line is a clamp and this little guy stuffed into a rubber grommet on the side of the "breather assembly." I'll take some photos of the spare motor tomorrow so we can have some reference.

You won't hear a click when you shake it. It's just a one way type valve with a single spring. I cleaned it up, used some q-tips and carb cleaner. Then I let it dry. Then I used my mouth to make suction/positive pressure. It worked flawlessly once it was clean.

I haven't driven the car since fixing this guy. Mine was pretty crudded up and didn't seal well when I first pulled it.

I'd say some models of this car had the component in the elbow. That's why 15 and 16 are different in the photo. Most auto parts stores list two different pcv's for the car. I found one that looks just like this one from advance auto.

So yes, in fact, there is, a PCV valve on the VX. It's just a pain to find/replace.
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[add|ct]

Wow, thanks for clarifying. I'm going to check it out first thing tomorrow morning. I bought a replacement for the 'elbow' when I first got this vehicle over a year ago, but I believe mine will be a straight 'in-line' guy like you pulled. So, any old Gumout, TB cleaner, brake parts cleaner will do to clean it up? I want to take mine off tomorrow and clean it.

Also, do you think its worth it to ever have to replace the grommets that the valve and the PCV valve(the actual one) seat into? The one at the elbow I noticed was fairly loose(though it never comes out during operation).

[benfrogg]

Yes, any cleaner will do. Use q-tips so you can get inside of it. I used probably 10 to clean mine.

You can replace the grommets if they are needed. To determine, let the engine warm up and idle nicely. Spray the grommets with TB cleaner (to protect the rubber don't use carb spray). Listen for changes in idle. Vacuum leaks will cause changes in idle. (sometimes subtle) If they change, replace the grommets.

We should post a new thread about this PCV discovery. Maybe even update the other vx/info links on the site.
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[add|ct]

I agree completely, thanks for the tips. I'm having to go over another thread to correct some advice I gave regarding it being an 'elbow' only system.

[imzjustplayin]

Originally Posted by add|ct

Wait wait wait...guys...is there some sort of place where an ACTUAL PCV "VALVE" is, and the thing we THOUGHT was the "VALVE" was actually just an elbow the entire time?!

ADDED: Okay from the manual on "Maintenance Schedule"

Every 60k miles "Inspect" Positive Crankcase Ventilation Valve"

How to determine?: If clicking sound is heard as you pinch the PCV hose between the PCV valve and intake manifold, valve is OK.


Is it alongside the runners at another rubber hose, then ben?

Also, what is your take on items 15 and 16 from the Honda Automotive Parts site in the diagram? For other models of the Civic?

Just re-read his posts where he discovers where the PCV valve is. The vacuum hose you found with the elbow, follow it both to the intake manifold and to the engine. Where the hose plugs into the engine is where the PCV valve is. Apparently the valve in this civic is a straight valve instead of an angled one like on my D16y7 engine.


The D16y5/Y8 use a straight valve just like all the D series engines for '92-'95 and I think it has to do with the intake manifold design. The Y7 uses a downdraft manifold while the 92-95 d series and the D16y5/Y8 use a sidedraft manifold. Side-draft manifolds are superior but Honda choose the down draft manifold to same money by not having to cast as much aluminum like on the older side draft manifold design. In 2001-2005 Civics, they're all downdraft manifolds and in 2006+ with the R18A1 engine, Honda reverted back to the side draft manifold but this time the entire manifold is plastic. This is getting way off topic but I felt I should share this cause I noticed the evolution of Honda's intake manifolds and can surmise the reasons Honda choose the manifold design that it did. To go full swing, this design impacts the design of the PCV valve.