2 part question

i have a 93 civic lx (engine = D15B7) that was not manufactured with
an EGR valve, which is weird to me cause i thought all modern
vehicles had one (since the late 70's). I failed california smog 4
times with twice the legal limits of NOX but everything else was fine,
i'm assuming the catalytic converter is the only thing that fixes this
right, as it is likely a 3-way cat?

also does anyone know is using a PCV catch can (oil catch can) is smog
legal in california? i know they are sticklers when it comes to
anything emissions related, as most things need to have a CARB
approved # stamped on them, but since the catch can only catches the
oil and does not stop the air from recirculating and burning up as
intended i dont see why it would be illegal, lowers emissions right?

i know high nox is due to high combustion chamber temps, besides
de-carbonizing the piston tops what else would lower nox on a non egr
vehicle?

 

maybe a bad O2 sensor? any codes set on the ECU?

 

That's about the size of it - the NOx stage of the cat is bad... assuming it
is a 3-stage cat. The absence of EGR makes me think that is so.

Make sure the timing is correct. Advanced timing will raise the NOx level,
but AFAIK a 3-stage catalytic converter hides that as long as it is working.

Mike

 

thanks guys... the O2 sensor was replaced by a shop the last time it
failed (in july 04) and it failed with harder NOX and a higher amount
of HC, though it was still in the legal limit....

no ECU codes...

might install a magnaflow direct fit replacement, if i can get them to
confirm it is california smog/noise legal...

sort of stumped cause i have another inspection coming up in june or
july.... i am now using the proper OEM NGK plugs, did some intake
cleaner throught the booster, idles much better, drives smoother...
cleaned a lot of carbon off the pistons.

you guys know what effect a PCV catch can would have on emissions? i
know it wouldnt do squat on NOX, thats temp related....but any others?

 

You're correct: A 93 Civic LX does not have an EGR system,
according to my Chilton's.

This seems like a helpful site:
http://www.aircare.ca/index.php?repinfo-glossary.php . See
especially
"Causes of Excess Emissions."

It puts a lot of emphasis on an improperly functioning EGR
system causing
high NOx , but it lists a few other causes, too. None are
the PCV valve.

http://www.interro.com/techgas.html#anchoreleven states
similar.

An improperly functioning PCV valve may cause high CO, which
you don't have.

What is a PCV valve "catch can"? Did you remove the PCV
valve?

 

thanks for checking the chiltons, i only have a haynes and it's not
very specific about that... PCV catch can is just a can more or less,
you take the hose that comes off the PCV valve and it connects to a
can, then another hose goes from the other side of the can and goes
back to where the PCV hose originally went, it just sits in-line of
the PCV hose to catch all the oil blowby so it doesnt gum up the
intake/valves etc... still allows the gasses to go by and get burned
up...

what are the other causes of high nox? high combustion chamber temps
due to carbon buildup is one but im not sure of any others

 

I can only guess:
defective rings
defective muffler
defective cat. coverter
valves not adjusted correctly
timing set incorrectly
defective plugs or plugs not gapped correctly

If you hook the engine up to a computerized engine tester--it should
discover the source of the problem. I show a recent post where someone
replaced all of the parts of his engine that might have caused his engine
to stall on a regular basis. It makes more sense to use testing equipment
to discover the exact cause of a problem instead of replacing a bunch of
parts that are working great.
Jason

 

Technically, the causes are high temperatures and rapid cooling, which
causes the NOx to "freeze" instead of decaying as the gases cooled.

Since the expansion time is pretty much determined by engine speed, that
leaves combustion temperature as the factor we can control. Carbon really
isn't an issue directly, but it can cause preignition which has the same
effect as advanced ignition timing. The two big culprits are ignition timing
and mixture. Advanced timing increases combustion temperatures, and a leaner
mixture at high throttle settings (when it should be rich anyway to
forestall detonation) does the same. EGR reduces the temperature by diluting
the mixture without affecting the air/fuel ratio.

Mike

 

good post. yes, check timing and mixture. mixture can be assisted by
running a couple of tanks with injector cleaner through the vehicle.
timing should be set with the maintenance jumper connected. and it
should be dead-on, not just close. regarding egr, it's often addressed
these days by increasing the overlap between exhaust and inlet valve
timing, so make sure the valve clearances are correct.

to the op, no, an oil catch can is illegal in california.

 

why is a catch can illegal?

good advice guys, someone from another newsgroup claims that the car
DOES use an EGR and said to go to

http://www.smpcorp.com/web_app/catalog/publicweb_bg.asp

then put in part # EGV551


i can see a mount near the valve cover where one WOULD go, but i think
the only cars of this era that had one are the ex and vx ?

may have to adjust the valves, it's pretty tough to get the timing
dead on considering the rpm's go up when the fan kicks on to cool the
engine, and finding 650rpm's EXACTLY on the tach is just a guess.

 

btw, rockauto.com is also coming up with the same product for the
D15B7, and that mount area is on the backside of where the valve cover
is, looks like where it would bolt on, only theres no opening into the
engine there, or is there supposed to be?

 

because vapor still vents to atmosphere. you have to operate a closed
crank case in ca.

that's a honda egr valve ok. but if you don't have one, you don't have
one! they're only on the automatics.

two things:

1. unless the spec is changed for the 92-95, the d15 idles at 750 +/- 25
rpm. look up the procedure for adjusting idle correctly, then leave the
engine management computer to do its job. /it/ controls idle speed -
/you/ don't!

2. the timing set-up procedure requires the use of an electrical jumper
which tells the ecu to keep ignition timing locked back. when you
examine the timing under strobe with the jumper installed, the timing
marks are very steady.* if the jumper is removed for normal operation,
the marks jump about because the ecu is always electronically adjusting
timing.


*. if the timing marks are /not/ steady with the jumper connected,
re-tension the timing belt - it's not been set correctly.

 

theres a screw on the throttle body to adjust the idle, i've never
messed with it so i should try again and get it as close to spec as
possible then try again, 750 rpms is canada, 670 is usa

yeah i did the jumper, then started the car (was hot already)

they seem to be steady until the cooling fan kicks on then the rpm's
get higher and the mark moves toward the back of the car

 

but i am usa. and that screw is not to adjust the idle. try it. it'll
not make any difference once the iacv valve compensates. the screw is
there to allow correct idle setup, and that's it. after that, it's the
iacv all the way.

then something's wrong. the timing stays steady if the jumper is
connected properly.