MIL questions

Hondarinos:

This is a follow up to my P0420 catalyst code. Luckily the Honda dealer
confirmed the malfunction and a new cat. has been ordered and covered with
the 8/80k emissions warranty. So now my MIL lamp is cycling on and off, in
about ~100 mile intervals. Ideally I would drive another car but this is my
only one and I need to get to work every day. Is this the kind of MIL that
puts my car in limp mode? Can I aggravate anything by driving it this way?
I don't feel any problems with drivability but I've been keeping it ginger
with the MIL glaring at me. I need to keep driving and I even had vacation
plans for a long weekend. Can I drive ~600 miles with the MIL? Thanks.

 

Since the cat is going to be removed anyway, don't worry about it.

About the only thing you'd ever damage in the short term is the cat itself,
and even then only if the engine is running extremely rich with a gross
failure of some kind.

What I *would* do is to go back to the dealer and make sure the code stored
is still P0420, in which case it's the old error come back again. As far as
I know, the engine does not go into open-loop with a P0420 code.

 

Since the cat is going to be removed anyway, don't worry about it.

About the only thing you'd ever damage in the short term is the cat itself,
and even then only if the engine is running extremely rich with a gross
failure of some kind.

What I *would* do is to go back to the dealer and make sure the code stored
is still P0420, in which case it's the old error come back again. As far as
I know, the engine does not go into open-loop with a P0420 code.

 

Thanks Tegger, makes me feel better about driving around. I have been extra
observant of running conditions, fuel economy is still consistent and there
is no extra soot collecting in the tail pipes. On other car boards, the
racers with high flow cats and no cats live with the code day to day, I
couldn't stand the constant MIL, doesnt feel good at all!

 

Thanks Tegger, makes me feel better about driving around. I have been extra
observant of running conditions, fuel economy is still consistent and there
is no extra soot collecting in the tail pipes. On other car boards, the
racers with high flow cats and no cats live with the code day to day, I
couldn't stand the constant MIL, doesnt feel good at all!

 

Speaking of extra soot, what are the usual causes of this?

I've got a fair bit of soot, but just this week replaced my plugs,
wires, and distributor cap and rotor with OEM. There was a fair bit of
corrosion on the terminals inside the cap, and on the rotor arm contact.
The plug electrodes were worn, the gap was quite wide, and there was
carbon on the plug threads (not unexpected given the tailpipe!). The
"arms" (what's the right term for the tab that curves around an provides
ground for the spark?) are somewhat white, which I think means they were
running too hot--I suspect this may have resulted from the engine
overheating I experienced with a stuck thermostat a couple of months
ago. I have a PCV valve in hand, but haven't done it yet.

What else should I be considering?

 

Excess soot is from running rich, burning oil.

But your tailpipe is always going to be sooty black as a normal condition
anyway. The good ol' days of a light grey tailpipe coating disappeared when
leaded gas was phased out.

Watch your gas mileage and oil consumption, that's the best way to tell how
well your engine is running.

You'll get carbon on the plug threads anyway. That's normal. You should see
your piston tops. They'll be jet black. Shine a flashlight into the spark
plug hole and you'll see.

The "ground electrode". The other one is the "live electrode".

Plugs running "too hot" is indicated by blistering on the ceramic
insulator. White ground electrodes *without* insulator blistering is
normal.

 

"weak" oxygen sensor is a prime candidate for this.

secondary candidates include [not in any order]:
timing - valve & ignition
air filter
injector fouling
bad gas
coolant sensor/coolant level
thermostat
egr valve

 

Thanks, Tegger. I know I'm buring oil, but I haven't been organized
enough yet to clock how much. I was shocked on a recent trip, though, to
find that the dipstick was dry. Added a quart, and it was still about a
half-quart low. Thanks goodness I didn't lose the engine!

OK, good. No insulator blistering.

Shit. Some little kid in my building has a recorder (the flute-thingy)
and is blowing on it with his/her as-yet completely undeveloped musical
talent... oy.

 

Hmmm. Is there a way to test the O2 sensor? I recently replaced the air
filter and thermostat, and ave run a couple of bottles of injector
cleaner through recently as well. Plan to check the timing when I can
lay my hands on the equipment. Seems to be running pretty darned good
after the new wires &c., so I may sit on it for a while and see how it goes.

 

check pcv valve!!! ignition timing can make a difference here too.

 

i don't know a convenient way. all i know is that it can make a huge
difference and a new sensor, while not cheap, pays for itself in terms
of much improved performance and better economy. i experimented with
some different oxygen sensors a while back and found after-market
sensors to be highly inferior. they get you through smog, but the car
doesn't perform. you can find nearly-new sensors in junk yards if
you're lucky.

 

Better get on the ball, or you WILL lose the engine. Then again, if the oil
is off the stick, the oils' been overheated and has lost much of its
effectiveness already. It needs to be changed ASAP.

In any case, if you're burning that much oil, your engine *may* be on its
last legs. Fill the oil up to the full mark. Drive 500 miles and check it.
Go from there.

IMPORTANT: As jim beam says, check your PCV valve. And the crankcase
breather hose. Pull the intake tube off the throttle body. Is it full of
oily gunge? If so, your PCV system is clogged, and the primary reasons for
this are 1) worn rings, and 2) sludge.




I've got an amateur drummer behind me. His musical talents are similarly
prehistoric.

 

Gadzooks! $175 at Majestic. That would have to be a pretty significant
improvement in economy. On mostly long trips with some city driving I've
been averaging just over 30 mpg. Have seen it as high as 32.1, and as
low as 27.6. How does this stack up to other manual tranny 94 Civic EX's
with ABS? That's the 1.6 liter engine.

 

Tell me about it--as I said, shocked. I don't quite understand how it
got that low--didn't realize it was burning that fast. I'm keeping a
close eye on it now. Thanks for the tip about overheated oil being less
effective.

I'll do that. I've already got a new PCV valve in hand.

Incidentally, some time ago there was a link to a page about sludge and
its removal. You recall where that was? It was pretty good, as I recall.

My sympathies. At least the kid goes to sleep at a reasonable hour...

 

if you're cruising at 90, that's ok. if you're cruising at 60, that's bad.

try the junkyard abe. you'll get all kinds of goodies there from
vehicles where the previous owner had just spent $175 getting a new
sensor, then forgot to check the oil...

 

whoops - not specific to you abe! sorry. i meant /any/ random
expensive failure like oil, coolant, thrown rod, anything that could
write off the car just after someone had spent a bunch of cash on it.

 

That's OK, jim, I'm LMAO over here... ;-)) Hey, I know when I've screwed
up bad and am man enough to admit it. Very little ego-involvement here.
Hell, I'm feeling *really* lucky my engine is still going right now, and
going fine.

As for speed, yes, cruising around 85-90, though my speedo looks to be
about 10% high.

Any tips on figuring out which O2 sensors are the ones replaced just
before the car was junked? I.e., what distinguishes a good one from a
mediocre one? I've got an ohmmeter.

 

i just went for the ones that looked the newest. i got one that i think
must have been in less than a month. pristine. the factors i use are
lack of oxidation/coloration on the exterior casing, clean wiring, and
on removal, minimal residue on the interior casing. you'll figure it
out pretty quick when you see a few different ones. /only/ go for oem
nippon denso though abe. the others suck. or you can be a guinea pig
and try a few different ones just for giggles.

 

You think I have time for that?? Hah! Thanks for the tips--if/when I
find time to hit the junkyard I'll be in good shape.