'90 Civic: Extremely sluggish low-end acceleration, poor fuel economy

"TeGGeR®" > wrote
Elle
> > Particularly if it's the original PCV valve, I would replace it. Just
> > one easy thing to eliminate.
>
> I fianlly replaced my original a few weeks ago. It had 14 years and
248,000
> miles on it. Didn't make a bit of difference to gas consumption or engine
> running.

By your own admission, you totally baby your car.

> New FAQ page on that saga:
> http://www.tegger.com/hondafaq/pcv-replace/index.html

Needs work.

You and I continue to disagree on this. A guzillion web sites back up my
(along with like every other regular's) position on this.

"Elle" > wrote in
nk.net:

> "TeGGeR®" > wrote
> Elle
>> > Particularly if it's the original PCV valve, I would replace it.
>> > Just one easy thing to eliminate.
>>
>> I fianlly replaced my original a few weeks ago. It had 14 years and
> 248,000
>> miles on it. Didn't make a bit of difference to gas consumption or
>> engine running.
>
> By your own admission, you totally baby your car.



That is my point. Cars that are not taken care of are the ones that suffer
from this.



>
>> New FAQ page on that saga:
>> http://www.tegger.com/hondafaq/pcv-replace/index.html
>
> Needs work.
>
> You and I continue to disagree on this. A guzillion web sites back up
> my (along with like every other regular's) position on this.



And every working mechanic I have ever spoken to about this says exactly
what I put up on that page.


--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

5-spd...I've been thinking about checking the timing for a while, but
last time I had the engine torn apart I studied the crank pulley for a
good 10 minutes in fairly good light looking for a timing mark and
found nothing.

Is it a paint mark? or a metal nub? I cleaned it off with some
degreaser when I changed my timing belt and still couldn't find any
mark.

What gives? Maybe this is just related to late-80s/early-90s Civics...
My 88 Toyota PU has a very obvious orange mark on the pulley and it's
really easy to see.

Bruce wrote:
> 5-spd...I've been thinking about checking the timing for a while, but
> last time I had the engine torn apart I studied the crank pulley for a
> good 10 minutes in fairly good light looking for a timing mark and
> found nothing.
>
> Is it a paint mark? or a metal nub? I cleaned it off with some
> degreaser when I changed my timing belt and still couldn't find any
> mark.
>
> What gives? Maybe this is just related to late-80s/early-90s Civics...
> My 88 Toyota PU has a very obvious orange mark on the pulley and it's
> really easy to see.
>
if the pulley is rusted, it's not so easy to see, but it's a tiny cut
between the alternator & a/c bands. should be painted too. you can't
see it from the side - you have to look down the gap between motor &
body near the l/h motor mount.

Well, I'm going to change the PCV just because I kind of doubt the
previous owner put in an OEM Valve, IF he changed it at all. One less
thing that could be causing my mileage problems, and it probably needs
done anyway.

But, I'd also like to check the timing... any advice on finding the
timing mark on the crank pulley? I assume it's just a little dab of
paint and that I'll have to put some white-out on it to make it visible
with the timing light, but I can't see ANY mark on the pulley. Nada.

And I need to short the contacts under the kick plate in the passenger
compartment to disable the auto-timing adjustment too, right? That
sounds easy enough, but if I can't find the mark on the pulley it's a
moot point.

Thanks guys.
-Bruce

Gotcha... should have considered that as I know you have to look down
and line up those two little pointy things on the timing belt cover to
check it. A little white-out will help me see it w/ the timing light
while the pulley's turning.

Thanks

"Elle" > wrote in
nk.net:


>
> You and I continue to disagree on this. A guzillion web sites back up
> my (along with like every other regular's) position on this.
>
>


I just tried two experiments on my own 1991 Integra just now.

-----------------------------

Firstly, I tried plugging the PCV hose shut. The idle dropped momentarily,
then climbed smoothly back up to 750 and remained there.

When I let go of the hose, the idle surged briefly, then settled back to
750rpm. As expected, the engine management system was adjusting air flow to
achieve correct idle speed.

-----------------------------

Secondly, with the car fully warm, I unplugged the PCV valve hose at the
pipe where it enters the intake manifold, so the PCV intake was completely
open as a massive air leak into the intake downstream from throttle plate.

The idle dropped momentarily, then began smoothly surging between 1,000rpm
and 2,500 rpm. As expected, the engine management system, crude as it is,
was attempting to adjust the mixture to be correct. The air leak being too
great, however, it was unsuccessful in doing so.

(Interestingly, air flow from the PCV valve itself stopped dead, suggesting
that ambient air pressure was keeping the valve shut. IOW, crankcase
pressure was lower than ambient.)

I then plugged the PCV intake pipe with my thumb, mimicking a plugged PCV
valve. The idle returned to a smooth 750rpm and stayed there.

I discovered that I could uncover up to a quarter of the PCV intake pipe
before the idle began surging again, the severity of the surging directly
related to the amount of exposed intake pipe.

-------------------------

Conclusion: Cars with engine management systems do not suffer noticeable
problems from a plugged or stuck-open PCV valve unless an extremely unusual
situation is present.

History:
I once had a 1975 Toyota Corolla with a carburetor and no feedback system.
This car would not idle at all with the PCV valve removed. Unlike the
Integras's feedback system, the carburetor was unable to compensate for the
excess air. I discovered this quite by accident when an aftermarket PCV
valve came apart on me.

--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

"Bruce" > wrote
> Well, I'm going to change the PCV just because I kind of doubt the
> previous owner put in an OEM Valve, IF he changed it at all. One less
> thing that could be causing my mileage problems, and it probably needs
> done anyway.
>
> But, I'd also like to check the timing... any advice on finding the
> timing mark on the crank pulley? I assume it's just a little dab of
> paint and that I'll have to put some white-out on it to make it visible
> with the timing light, but I can't see ANY mark on the pulley. Nada.

Like Jim said, it is hard to see. You should go at it from the top, and with
a flashlight, using the directions he gave.

That degreaser you applied may have helped shorten the life of the pulley's
timing paint marks. The marks are mechanically etched into the pulley,
though, so they should still be somewhat visible.

You do realize it's four marks, all within about 10 degrees (too lazy to
think about the exact degrees apart they are), right?

There was a photo online of the c. 90 Civic's timing marks at a certain site
that I'm trying to pull up now. My Chilton's has a drawing and photo, so
Autzone.com and probably the UK site should have at least the drawings, too,
under "ignition timing." I'll post a link if I find it.

> And I need to short the contacts under the kick plate in the passenger
> compartment to disable the auto-timing adjustment too, right?

Yes.

"Elle" > wrote
> There was a photo online of the c. 90 Civic's timing marks at a certain
site
> that I'm trying to pull up now. My Chilton's has a drawing and photo, so
> Autzone.com and probably the UK site should have at least the drawings,
too,
> under "ignition timing." I'll post a link if I find it.

FWIW, go to http://www.honda.co.uk/owner/ConcertoManual/index.html , and
click on Engine Tune-Up, then "Ignition Timing... " at the bottom for some
drawings of the engine and its timing marks. Check out the CRX manual's
drawings, too, at the UK site. They are slightly different.

www.autozone.com has the drawings and photo (under its free repair guides;
"engine performance and tune-up"; "ignition timing") too. I have been having
error messages when I accessing some of Autozone's sites from home, but I
found that repeatedly refreshing usually clears this up.

> > And I need to short the contacts under the kick plate in the passenger
> > compartment to disable the auto-timing adjustment too, right?
>
> Yes.

Ignore the UK site's steps on this. The c. 1990 Concerto and CRX have a
different set up for disabling the automatic ignition timing adjustment.

Bruce wrote:
> Gotcha... should have considered that as I know you have to look down
> and line up those two little pointy things on the timing belt cover to
> check it. A little white-out will help me see it

indeed, but don't make the mark too big - even 2 degrees out made my 91
crx hesitate.

> w/ the timing light
> while the pulley's turning.
>
> Thanks
>