1997 Civic EX low fuel milage solution

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Marco - 07 Feb 2006 00:34 GMT

Just thought I'd pass along a bit of self-acquired wisdom. It may apply
to more than just civics.

My 1997 Civic EX (SOHC V-TEC)[D16Y8] was averaging between 24 and 26
mpg. I knew there had to be a problem somewhere since it should have
been much better.

Changed out spark plugs, wires, air filter, fuel filter, AT fluid, etc.
None of it worked, so I said the hell with it..

A month went by, and then I decided to have a go at it again. I scanned
the honda newsgroups and I can't remember who suggested it to someone
else, but it ended up being the PCV.

The PCV! A $2.75 part boosted my milage to between 31 and 33 mpg.

I had a hell of a time finding it on my car. On a 97 Civ EX, you have
to get under the car and look above the oil filter a few inches towards
the passenger side. Even the picture in the haynes manual is vague.

Another milage tip: Keep your tires inflated to the pressures shown on
the sticker on the driver side doorjamb.

-Marco

Reply to this Message

Elle - 07 Feb 2006 00:52 GMT

Good work. A few questions for the archives, since this has been a bit of a
contentious issue in the past here, with some saying PCV valve
malfunctioning won't affect mileage noticeably, and others saying oh yes it
can. (I replaced mine on my 91 Civic in 2003, and the mileage shot up
10-20%. The old PCV valve was chock full of waxy buildup but may have worked
had I cleaned it thoroughly.)

How many miles are on your car?
Did you do the test where you pinch shut the tube attached to the PCV valve
and listened for the "click"?
Did the old PCV valve appear clogged with anything?
Where did you buy this valve for the bargain price of $2.75?? Is it OEM?
One of my favorite online parts sites sells it for ~ $12.

I remember reports of at least one 1990s year of Honda having a hellaciously
located PCV valve. For the record, many other years have much easier to
replace PCV valves.

> I scanned the honda newsgroups and I can't remember who suggested it to
> someone else, but it ended up being the PCV.
[quoted text clipped - 4 lines]
> get under the car and look above the oil filter a few inches towards the
> passenger side. Even the picture in the haynes manual is vague.

Reply to this Message

Marco - 07 Feb 2006 02:36 GMT

> Good work. A few questions for the archives, since this has been a bit of a
> contentious issue in the past here, with some saying PCV valve
> malfunctioning won't affect mileage noticeably, and others saying oh yes it
> can. (I replaced mine on my 91 Civic in 2003, and the mileage shot up
> 10-20%. The old PCV valve was chock full of waxy buildup but may have worked
> had I cleaned it thoroughly.)

I'm no auto genius or anything, but I've done my share of major work on
my own cars. The only thing I did was change the oil, filter, and PCV
this time, and I noticed much better milage right away. I'm still
looking to see if I can get even better milage somehow.

> How many miles are on your car?

It'll click past 129,000 miles in a day or two.

> Did you do the test where you pinch shut the tube attached to the PCV valve
> and listened for the "click"?

Never heard of that trick.. Nope.

> Did the old PCV valve appear clogged with anything?

It appeared clean. I didn't see any sludge or anything on it, and I
shook it around to see if it was loose, and it was. I didn't look
closely, but I thought it seemed to stay open..? I can't verify if it
was actually clogged or not.. sorry there.

> Where did you buy this valve for the bargain price of $2.75?? Is it OEM?

I got it at Advance Auto Parts.

I'm now kicking myself (I completely forgot), because I refused the part
that they tried to sell me because it looked nothing like what I pulled
from the car. The guy at the counter went back and found 2 valves that
looked just like it, and I picked the one that was as exact as I could
tell. If I can find my receipt, I'll post the part# here.

Now I'm wondering if an OEM PCV will make it get even better milage.
I'm gonna do it.

> One of my favorite online parts sites sells it for ~ $12.

For common items I'll go to the nearest auto zone or advance auto. Like
oil, filter, air filter, fuel filter, plugs..

For everything else I'll go to the honda dealer. Like ATF, cam cover
gasket, oil pan gasket, water pump, t-belt, etc..

I haven't bought parts online yet, but from seeing the links at
Tegger.com, I'll be doing that from now on unless I 'gotta have it now'.

> I remember reports of at least one 1990s year of Honda having a hellaciously
> located PCV valve. For the record, many other years have much easier to
[quoted text clipped - 8 lines]
>>get under the car and look above the oil filter a few inches towards the
>>passenger side. Even the picture in the haynes manual is vague.

Reply to this Message

Elle - 07 Feb 2006 02:52 GMT

> I'm no auto genius or anything, but I've done my share of major work on my
> own cars. The only thing I did was change the oil, filter, and PCV this
[quoted text clipped - 4 lines]
>
> It'll click past 129,000 miles in a day or two.

Good data point.

My 91 Civic's was at about 138k miles when I took it off and inspected it
for the first time. I think it was due sooner. I wasn't paying close
attention to fuel mileage back then. My Civic's owner's manual says to
inspect the PCV valve every 60k miles/4 years. (I know: Doh.)

Now I take it off and soak its guts in PB Blaster for a minute about once a
year. It stays very clean.

>> Did you do the test where you pinch shut the tube attached to the PCV
>> valve and listened for the "click"?
[quoted text clipped - 7 lines]
> I thought it seemed to stay open..? I can't verify if it was actually
> clogged or not.. sorry there.

Is your valve mostly plastic looking?

I ask so as to try to ascertain wear rates.

My 91 Civic's PCV valve appears to be all metal parts.

>> Where did you buy this valve for the bargain price of $2.75?? Is it OEM?
>
[quoted text clipped - 8 lines]
> Now I'm wondering if an OEM PCV will make it get even better milage. I'm
> gonna do it.

I don't recall reading reports on whether OEM matters for the PCV valve. I
was just curious. At least we can tell the poor college kids coming here
that, if they're really low on cash, they could buy a cheap-o PCV valve at
Autozone et al.

By contrast, there is a wealth of anecdotal reports that one should put only
the plugs listed in the owner's manual into one's Honda. (NGK in my case.)

snip but comments noted

> I haven't bought parts online yet, but from seeing the links at
> Tegger.com, I'll be doing that from now on unless I 'gotta have it now'.

A friend of mine and I are both finding our new, local Honda dealer to be
way more competitive than dealers in the past. Not on everything, but on
some parts.

Here's my site on better gas mileage, FWIW:
http://home.earthlink.net/~honda.lioness/id11.html

Reply to this Message

Marco - 08 Feb 2006 02:31 GMT

>>I'm no auto genius or anything, but I've done my share of major work on my
>>own cars. The only thing I did was change the oil, filter, and PCV this
[quoted text clipped - 11 lines]
> attention to fuel mileage back then. My Civic's owner's manual says to
> inspect the PCV valve every 60k miles/4 years. (I know: Doh.)

Yeah. I changed mine out about 2000 miles ago, and I still stand by the
better mileage in my case..

> Now I take it off and soak its guts in PB Blaster for a minute about once a
> year. It stays very clean.

Sounds like a good technique.

>>>Did you do the test where you pinch shut the tube attached to the PCV
>>>valve and listened for the "click"?
[quoted text clipped - 13 lines]
>
> My 91 Civic's PCV valve appears to be all metal parts.

The old PCV was made of 2 different color plastics. Black and Red.
Dunno if it was OEM or not.

The new one is all black plastic.

>>>Where did you buy this valve for the bargain price of $2.75?? Is it OEM?
>>
[quoted text clipped - 16 lines]
> By contrast, there is a wealth of anecdotal reports that one should put only
> the plugs listed in the owner's manual into one's Honda. (NGK in my case.)

I couldn't find the receipt for the new one. I called Advance Auto, and
they said that the purchase won't show in the records unless it was a
warranty item. So, no luck there.

Well, I'm going to get a new OEM PCV. I figure I can reasonably assume
that it will get at least the same milage or better. But, its just a
simple valve.. and so I'm not counting on anything.

> snip but comments noted
>
[quoted text clipped - 7 lines]
> Here's my site on better gas mileage, FWIW:
> http://home.earthlink.net/~honda.lioness/id11.html

Excellent site! Looks sharp and has some great info.

I wish I had a camera when I changed out the engine in my sister's '87
Civic (4 door sedan). Carbeurated. 800,000 vacuum hoses. A nightmare.
Many stories to tell, and many lessons learned.

-Marco

Reply to this Message

Elle - 08 Feb 2006 05:42 GMT

> Elle wrote:
>> My 91 Civic's was at about 138k miles when I took it off and inspected it
[quoted text clipped - 4 lines]
> Yeah. I changed mine out about 2000 miles ago, and I still stand by the
> better mileage in my case..

... and so suggesting aftermarket PCV valves have drastically shorter lives?

This should be an interesting multi-year experiment.

> I wish I had a camera when I changed out the engine in my sister's '87
> Civic (4 door sedan). Carbeurated. 800,000 vacuum hoses. A nightmare.
> Many stories to tell, and many lessons learned.

I'll bet. Wal-Mart sells a perfectly good Kodak digital camera for $99. :-)

Reply to this Message

SoCalMike - 08 Feb 2006 06:18 GMT

> I wish I had a camera when I changed out the engine in my sister's '87
> Civic (4 door sedan). Carbeurated. 800,000 vacuum hoses. A nightmare.
> Many stories to tell, and many lessons learned.

i vaguely remember replacing a carburetor on my moms '77 accord. i
imagine they did they best they could, considering the era. LOTS of
hoses hooked up to banks of little vacuum doohickeys on the firewall.
after 14 years, i doubt any of em worked.

Reply to this Message