Car went from being very clean to failing emissons in the last 20K
Two years ago, had the dealer replace the oxygen sensor, put new plugs,
air filter, pcv valve and this brought it into passing. This made it
pass, but it was no where near as clean as the previous test cycle. The
catalytic converter was replaced 25K miles ago at the dealer with oem
new stuff. All the emissions stuff is connected.
Car has 200k miles. Doesn't burn much oil, but does leak some oil down
the valve stems.
I don't think there are any vacuum leaks.
Car doesn't idle quite as nicely as it used to.
What is the most likely suspect causing emissions failure on this car?
Do some of you make this up to get a rise from us or has it occurred to you
all that valves are for gasoline intake and exhaust removal and unless you
have (nope) a diesel they don't DEAL with oil much? Have you got a nasty
case of blow-by? When was the last time you checked your rings? Did your
mechanic even look?
I'm mildly flabbergasted. HUH...whatever.
The engine is old and with mobile one oil, it puffs on start up only
occasionally. It depends on how long it's been parked, weather its on a hill
and that sort of thing. It's done this for ten years and is no different
Yes, it is normal for this engine with this milage. It's no different now
than when it passed emissions with flying colors.
I could use some help here instead of sarcasm. Thanks.
Steven Dinius wrote:
I don't think it's normal or you wouldn't ask? We have scads of FI 4.3
Blazer 4X4's in the area and they get beaten up far worse than yours. Don't
accept that it's the status quo. If you've got oil leaking into your valves,
it still sounds to me like your rings are worn out. ESPECIALLY at 200K.
Sarcastic, sure, but I'm only flabbergasted bcuz this seems like common
sense to me--it has to be looked after even more after 100-120K. Not to
mention it's seventeen years old. I have a 1986 2.5 four and don't I know
that (I have only 114K).
A 4.3 V6 is effectively a 350 small block missing two middle cylinders. Small
are notorious for puffing a bit on startup after sitting; it's not a
catastrophic situation, and, assuming the smoking desists after a few
moments, is not an indication of piston ring/bore wear. Rather, it
typically indicates worn valve guides/seals. Worn rings would cause oil
smoke emissions continuously and to a more severe degree with the hammer
down. Posting the ppm and %
numbers from the emissions fail report would indeed be helpful.
As for Mr. Dinius and his 'common-sense'-induced flabbergastedness,
methinks his muffler bearings are binding and causing his Johnson rods to
bang into his lugnuts, so to speak. Let's all sing to the tune of RawHide:
"Trollin', trollin', trollin'
keep them trolls trollin'..."
On Wed, 12 Nov 2003 22:40:08 -0700, Steven Dinius wrote:
On Wed, 12 Nov 2003 22:40:08 -0700, Steven Dinius wrote:
Not much on the common sence then are you MR. Dinius. Lets see, oil leaking
onto the valves. Sure, it does happen. Now Rings worn out. Yep, that will
happen too. BUT, the rings worn out CAUSING the oil to leak onto the
valves? Well, lets just say it COULD cause a little bit of that IF the
rings were worn out enough to be letting enough back pressure into the crank
case to push oil through the valve guides and seals, AND the pvc valve is
completely stopped up AND ALL of the gaskets sealed pressure 100%. So
basically, that is NOT the problem.
So basically, the little bit of smoke at startup is more that likely caused
by worn valve seals, assuming that there is only a small amount of smoke
that goes away really fast.
It would appear that Mr. Dinius' sole purpose as a new entrant into these
NewsGroups is to see how many posts he can make in the shortest period of
time. EARTH TO MR. DINIUS - We want quality of posts, not quantity of posts
in these NewsGroups!!! If you have nothing to say, please remain silent!!!
reveals that you wander around from NG to NG
irritating everyone with your asinine comments. This is evidenced by the
attached Google Link which shows 118 posts under this name alone and gawd
knows how many other trolling aliases you have! A quick view of several of
your posts says it all! A quick warning to regulars to the Group, don't
waste a lot of time reading Steve's posts because they are basically all the
same. They lack substance, say nothing, and only serve to irritate members.
The only ass is U. I don't care one way or the other if you fart around
looking for my posts <hah>
Does that make you proud?
Steven Mark Dinius
416 NE 3rd St
Ontario, OR 97914
you're in Canada
I repeat U are still an ass
former tags: email@example.com, firstname.lastname@example.org, email@example.com
NO suspensions for any reasons--changed ISP and dropped accts when money was
I ain't no damned troll. I am bipolar. Diabetic. Hypertension. Cholesterol.
Arthritis. Sick of idiots hastily calling me an idiot. F--- you. Look in the
mirror while you chew on your toast. You ain't Jesus either. Bark without
thinking. You got a block setting. Use it. I am not anonymous nor did I
create a false tag that would bounce back with <550 User unknown>. And maybe
not too happy about my relationship falling apart. Sorry if it gets in the
Did you have fun?
reveals that you wander around from NG to NG
Perhaps you could inlcude the test results with this posting so everyone can
see then specific question such as HC is out of limit at idle or at certain
rpm. It is diff to offer suggestion.
December 1998 the car had 205,000 miles on it and tested out at:
HC 0.26GPM state limit 2.00 GPM
CO 2.2GPM state limit 30.0 GPM
Comfortably clean compared with limits.
In 2000 The car failed emission for both numbers I think, meaning it exceeded
2.0GPM for HC, 30GPM for CO. At that time, the car had around 214,000 miles.
At that time, I had a new O2 sensor installed, PCV Valve, plugs, oil, air
filter.. that sort of thing. The catalyst was replaced around 199,000 miles
and should be adequate. The exhaust system is in new condition and the car
garage kept. The EGR valve seemed to operate in 2000 when a vacuum was
applied but I know nothing about the condition of the ports leading through
the EGR pathway.
These repairs brought the car within state limits in 2000, but still very high
for the car compared with the previous emissions testing. I think HC was over
1.3 GPM.. As it was driven on the treadmill in 2000, the graph of HC was all
over the place from clean to fairly high.
The car now has around 226,000 miles on it. I don't know for sure what is
failing but my guess is both HC and CO are out. The paperwork is with my
nephew who has the car now. He went to get inspection and emissions.
Emissions fails. I don't have the numbers back from him yet. I don't know if
they even gave them. It failed.
I know that a little seepage down the valve guides that causes a puff
occasionally at start up is not causing the emissions failure. The car has
done this for all the time I've owned it, including during the fabulous
results in 1998. It's no worse now than ten years ago. I've used Mobile One
in this engine since 160,000 miles when I bought it. It's been serviced with
adequate oil change intervals using Mobile One. I'm confident there won't be
any significant mechanical engine wear in the last 20K miles compared to when
I got it at 160K miles.
I doubt very much that the rings are suddenly shot in 20K miles, blow by
became outrageous and other assertions that a well meaning newsgroup member
The plugs looked great in 2000, even with 50,000 miles on them. Even the
original one that had never been changed ( hard to reach) before was not
More likely, something has happened suddenly in the way of vacuum leak, carbon
in the EGR path or dirty injectors. The car has seen limited use these recent
years because I am in poor health. Perhaps fuel sitting has effected injector
I was hoping someone here has experienced and fixed the same rapid
deterioration in emissions performance and could point us in the right
direction. My nephew can't afford to drop this by Mr. Goodwrench for all new
parts. I'll try to get his readings if he has them and post them later.
The car runs good, doesn't smoke and sure has hell doesn't need a ring job.
If we go ahead and assume (dangerous, I know) that the car failed on HC,
CO or both, as before, we know that the most likely culprit is a fuel control
problem. EGR is probably not an issue, as this would likely either be causing
low power complaints (stuck open) or a NOx failure (stuck closed). If I
further assume (I'm not getting into deeper trouble, am I?) that this is a TBI
car, we're dealing with a speed density system. A vacuum leak in
theory should only increase the idle speed--the system should meter
additional fuel to compensate (ever had a Saturn come in because it was
idling at 3000 rpm, only to find the culprit was a disconnected PCV hose?).
High CO typically indicates over-rich mixtures, high HC should be
accompanied by high oxygen content as indication of a misfire (if the
fuel ain't burnin' at all, neither is the oxygen). Misfires can lead to
a vicious circle; the unburnt oxygen from the miss is read by the O2
sensor as a lean condition; we then go richer, foul the plugs worse, and
may continue misfiring and going richer until the cat goes Chernobyl.
This should, of course, be noticeable to the driver ('trailer-hitching'
sensation) before things get this bad.
Excessive HC can also be
traced to carbon buildup in the chambers--carbon acts like a sponge; it
soaks up fuel, preventing it from burning, then when the exhaust valve
opens, it releases the HC into the exh stream. The carbon forms, of
course, from rich mixtures, so something else would be going on in this
case. Of course
this isn't set in stone, as tailpipe readings can be distorted by the
converter (by its function or lack thereof). High HC and CO reading could
also be caused by testing the car while it is cold.
If I was faced with making this diagnosis, I would first do all the obvious
stuff, such as checking the air filter, looking for
broken/damaged/disconnected wiring, and read the plugs. Check for an
exhaust leak at the manifold; if the exhaust scavenging pulses are
pulling outside (fresh, oxygen-bearing) air into the exhaust upstream
of the O2 sensor, the sensor
will misinterpret the ambient oxygen as a lean condition and increase
pulsewidth to richen up the motor. I would watch the O2 sensor's output
with a scope or graphing multimeter as well (assuming you can get access
to one). If you can do this, artificially altering the mixture by
indtroducing propane into the TB or inducing a vacuum leak should get a
response from the sensor. The ECM should immediately correct, returning
the sensor to its appropriate "drunk on a bridge" waveform, of course,
but a short, immediate anomaly should be observed from the O2 sensor.
The converter is also a distinct possibility, especially if another
failure has caused an over-rich condition; excessive raw fuel in the
exhuast cooks cats. Apart from the rotten egg smell (sulfur dioxide)
that may accompany a
failed converter, I'm always hesitant to blame a (pricey) converter
unless I have the luxury of using OBD II's downstream sensor as a
comparison (no such animal on an '84).
Now that I have babbled on after making assumptions, let's hear some
Best of luck,
On Thu, 13 Nov 2003 15:29:58 -0700, no one wrote:
I'm not going to venture a guess about mechanical or electrical problems
but I will tell you this. I had the same problem on three different
(high mileage) vehicles and it cost me $2 to fix. I just flushed the
engine with Gunk 5 Minute Motor Flush, changed the oil and filter and
then drove on the interstate for about 30 miles (voila' - problem
solved). It works for me but will it work for you? Only one way to
Thanks for your detailed answers. You seem to understand the issues better than
those here saying the engine is shot and similar comments. I have some more
including the recent emissions report now and I'm not sure how this would effect
your conclusions and advice. If you have anything to add, I'm keenly interested.
Concerning the other post about an oil motor flush I think its a bad idea to
disturb any grunge that might have collected inside the valve covers where it
could get loose and block an oil passageway in this high milage engine. I think
it might be a good idea to change the oil before retesting though, and maybe go
to 10W- synthetic in place of 5W- to reduce seepage past the valve guide. BTW,
the seepage and puff at start up is a very occasional thing which and happens
the car is parked on certain slopes and restarted 30 minutes later. There is no
smoke on wide open throttle or any other time.
I believe all the vacuum lines are connected okay. We've not looked for manifold
leaks, intake or exhaust. The air pump is connected. All the emissions stuff is
intact. I never saw any reason to detach these devices.
The test in December 1998 at 205,000 miles showed
HC 0.26 GPM state limit 2.00 GPM
CO 0.26 GPM state limit 2.2 GPM
NOx .5 GPM state limit 3.0 GPM
I think that is a pretty good showing for a car with this milage. I'd buy
if they still made them.
I think the car got a new catalytic converter around 190,000 something miles. I
had the converter replaced then becuase it was plugged. I believe it was the
original converter too. The result was the car had no power at wide open
throttle. I guess that is what you mean by "trailor hitching" effect. The car
then felt like it was towing a tractor trailor behind it. It plugged rather
quickly and dramatically too. From 160,000 miles to 190,000 miles the car passed
with the original converter.
From the 160,000 miles point until 200,000 or so, the car would ping at light
engine loading and cold weather after an hour of freeway driving. It would
bring the check engine light on after an hour of highway driving. I think the
computer code reported EGR issues on the primitive computer as read using the
"paperclip" method. I'm not sure, because the error message for codes was
different on each web site I looked at for this information. I don't have the
shop book. I don't recall the codes read out on the dash lamp now. Might have
been 32, and 43 but my memory fades. They either were MAP sensor or EGR
depending on the web site. There are no codes in the computer now.
In 2002 the car failed emissions. I had a new O2 sensor put on, new plugs, air
filter, pcv valve and new plugs. The old plugs looked great too. There was no
significant oil, carbon or deposits on them and no cracked insulators. I had
change them previously at 160,000 miles. One plug seemed to be original to the
car. It seems most cars have one of these plugs that are too difficult to reach.
My friend had smaller tools and got it wapped. I did the work at 160K and my 1/2
inch socket set that could not reach the one plug.. and the others look pretty
good so I had reached a point of diminishing returns I thought. That original
plug really looked good for the age too. In fact, they all looked better than
15,000 miles old plug on my old 350 cubic inch 68 Firebird. There is a
(temperature?) switch on the EGR valve, and it's wiring was loose, so I had this
swapped out too when things failed in 2002.
Anyway, in 2002 the car passed marginally at about 60% of the state limits, which
compared with the '98 readings tells me there was still a problem. I still need
to get those readings, the paperwork is somewhere. But pass is pass and I drive
very infrequently, so it didn't interest me much The car no longer pinged or
brought the check engine lamp on after an hour's driving.
The new test is run now 15mph and 25 mph. The readings are as follows:
15 MPH HC 105 (pass) state limit 108
25MPH HC 137 (fail) state limit 106
15 MPH CO 0.06 (pass) state limit 0.61
25 MPH CO 0.12 (pass) state limit 0.12
15 MPH NOx 1389 (fail) state limit 823
15 MPH NOx 1457 (fail) state limit 750
My nephew didn't know to drive the car on the highway a bit before driving to the
test station, so he jumped into the car and drove right over. The catalyst was
probably not up to working temperature when he got there. D'oh! It probably
wouldn't have made the NOx pass anyway though. I think the HC would have been
sneeked through had the car been warmed up instead of being driven less than ten
minutes in traffic.
My friend who has the same engine in his GMC Jimmey says that he rebuilt the
throttle body with a GM kit and his passed afterwards. He also said that the EGR
passages become blocked with carbon with these high miles. He had 140,000 miles.
I've read around the net that high NOx means the mixture is burning too hot and
that failure of the EGR circuit can cause this... along with catalytic converter
and some other issues. The HC is a bit high too and I think that means it's
running rich. I think that 15 and 25 mph are fast enough to try to open the EGR
path. So perhaps that is the issue.
My friend with the GMC is planning to visit to clean and reassemble the injector
TBI assembly. I'm open to more suggestions before he comes next week. We really
need this to pass on the next go w/o spending lots of dough. If it needs a new
converter, we'll buy one. On my truck, I've replaced the cat and it made very
little difference though. The engine has to be working right first.
Thank Mark and others who contributed thoughtful ideas!
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.