gokus-eg2

Recently my cars been idleing real low like 100 to 200 and sometimes even stalls out when I try to take off, only at times tho when I come to a complete stop, other than that it rides perfect,I have been noticeing my gas mile age going a bit down...its not throwing any cells or anything ....would a bad , stuck open or stuck shut pcv valve cause this, I have done everything from replacing cap and rotor,thermostat,all new wires n plugs,there's no vaccum leaks anywhere,I cleaned out both aicv and fitv, I need to get this fixed this week cuz my smog is due,hopefully someone can help me out ....thanks ahead of time

techtalk

Hey man,

A faulty PCV valve may stick or not close properly, thereby allowing an excess of oxygen to enter the combustion chamber. Excess oxygen dilutes the air/fuel mixture ratio, causing a rich fuel mixture. This rich mixture can lead to a build up of back pressure in the exhaust system, which can cause engine stalling and a decrease in overall engine performance. So your PCV valve could be bad.

Another prominent indicator of a bad PCV valve is oil deposits found on the air filter, which may result in greater fuel consumption and the need to clean or replace the air filter prematurely. Have you noticed this issue with your ride?

If you need to replace the PCV valve on your Del Soul here's the rundown on the part: OEM part # 17130-PM6-003- $14 - $19, depending on where you source it from.


P.S: I forgot to mention that oil leakage could be a sign of a bad PCV valve. When a PCV valve malfunctions it causes crankcase pressures to increase, forcing oil through seals and gaskets. Look for excessive oil consumption and/or leaks!

gokus-eg2

Yea I actually have noticed a performance decrease on it , even with all the new ignition parts, that should have made it ride smoother and better ,I also just noticed the pcv is kind of ghetto rigged from the previous owner they put a after market looking one in the middle of the hose rightby the throttle cable..... But yea it makes sense I'm sure thats the problem , there was oil on my filter last night when I was checking it ....thanks a lot man ill get right on it when I get home.....incase that wasn't my issue what other possibilities could be causing my low idle and at times stalling? Would dirty connections to sensor s cause anything?

strategy400

Wouldn't extra oxygen introduced into the intake cause a lean mixture not a rich one? Unless somehow the ECU is detecting lean and enrichening or something..

Manual says to carefully pinch PCV hose between manifold with a rag and pliers and PCV valve and make sure there is a click noise from the valve.

Also appears the entire circuit is after the air cleaner so oil on the air cleaner seems unlikely.

I'd also think the crankcase pressure does increase with a clogged PCV valve, but only because of an absence of the manifold vacuum (not really extra pressure but reduced vacuum). The PCV valve is opened to varying degrees by varying manifold vacuum.

I think the throttle position and RPM also throw variables into the whole operation. I notice when I coast down the mountain on the way to work with my foot off the throttle for around 5 minutes at 80 mph the temp gauge goes way down. I used to think this was an absence of combustion but now I also think the manifold vacuum must be high and the PCV valve is wide open drawing in cool air from the intake tube througout the crankcase as well as subsequently into the combustion chambers, exhaust, etc.

Former User

I don't think a bad PCV valve will have much of an effect on gas mileage, though it can affect idle control. The O2 sensor should be able to adjust the air:fuel ratio to compensate for any air intake effects of a bad PCV valve.

Have you checked the ignition timing with a timing gun?

Did you install the same NGK spark plugs recommended in the owner's manual?

fleabag

Well you would be wrong. A bad PCV should be well known for causing a measurable performance decrease and fuel consumption increase whilst putting the car at risk of burning oil thanks to the increase in crankcase pressure.

Former User

Provide some reliable evidence (as your comments are often misinformed) and also give some plausible explanation for how you think a bad PCV valve would have a dramatic effect on gas mileage. And don't turn this into an argument. Just state the facts, if you have any.

Also explain how a clogged PCV valve would substantially increase crankcase pressure. Before any significant pressure could build up, it would be relieved through the breather hose, right?

fleabag

http://www.moparmagazine.com/2011/ma...ance_tips.html

go into any search engine, type "PCV valve fuel economy" and I'm sure you'll get a very long list.

As for WHY a clogged PCV valve would increase crankcase pressure....? Because the PCV valve is right at the breather box which is on top of the crankcase, if the buildup in gasses can't escape that valve, then it will find its way through any other passage, including the grommet in which the PCV valve sits in which is why you'll commonly find grime on top of old PCV valves. Just because there is a breather hose at the valve cover, it doesn't mean that the gasses will vent because you still have that clogged PCV valve. Imagine sucking on a steel water bottle, all you're going to do is create negative pressure which is not what you're suppose to be doing but instead having a flow of fresh air running through the engine block back into the intake. Do you need me to post the diagram of the breather system from the helms manual?

I've done actual testing of before and after the installation of PCV valves and the fuel economy benefit is usually in the range of 10-30% improvement. There is also a noticeable performance difference after replacing the valve in engines that are running optimally. Obviously a worn engine will benefit less from a clean PCV valve than a newer engine thanks to the less tight seals in various places, especially in the rings.

I've seen cars run extremely poorly when they had clogged PCV valves but after replacement, it was like nothing had ever happened. The way the problems manifest themselves when you have a clogged PCV valve will vary greatly which is why this item is always up for replacement. I can't believe I really have to substantiate claims such as this which I thought were common knowledge, especially on a message board such as this...


I think the better question for you is, do you keep track of your fuel economy and have you ever replaced your pcv valve?

Former User

Reminder: I'm looking for reliable and relevant information.

How is MOPAR (Chrysler products) relevant to Civics?

Why do you think crankcase pressure could not be relieved through the breather hose if the PCV valve is clogged? What you say in a long paragraph really makes no sense.

You did a scientific test for the effect of replacing a clogged PCV valve on Civic gas mileage? Please give more details. Did you replace something else at the same time?

You do understand that the PCV valve is purely a device to reduce emissions, right? For 5th generation Civics but not generally 6th generation Civics, a clogged PCV valve can cause a low idle speed. But that's about it.

gokus-eg2

I replaced the pcv valve and got a new hose to and my idle problem went completely away , my ride idled like a brand new car , I'm gunna commute to work in it tommorow so ill see if there was any performance difference or improvement, but the idle problem is completely gone thank god, I spent about $100 bucks replacing cap and rotor spark plugs thermostat and wires , when all it was , was a $2 valve, for those with older cars n trying to figure out wether to replace it or test it over a idle issue like mine they can't figure out , just replace it , its $2 dam dollars...thanks everyone

ne0tas

Hm interesting..I might try this. My car sometimes has an idle problem and never thought of checking the pcv valve

Van Helsing

I replace my PCV valve on my 2001 Civic DX sedan and it made a huge difference in performance and overall drivability! The car had 174,000 miles on it. I also had replaced the AIC and that helped some, but the PCV replacement smoothed out everything. I'm wondering now if the AIC even needed replacement! doh!

clkupai

Hi
this sounds like a similar issue i have with my idle. anyone direct me to a how to change your pcv valve write up??? i cant seem to get mine off!
cheers

strategy400

^this

If there is any pressure exerted on the seals or gaskets it would be from the forces of excessive blow-by from worn engine components (rings).