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[OT] Automotive emission controls

B

Beloved Leader

Jan 1, 1970
0
Ancient_Hacker said:
You might have carbon buildup on the intake valves. No simple way to
fix that.
take the highway, driving as fast as reasonable for 20 to
40 miles. That might do the trick.

GM sells this stuff called "Top Engine Cleaner." I've used it before, a
few years back, on this car. In August, the Cadillac techs felt it
would be a waste of money, but after I flunked the test again on the
4th, one of them suggested pouring in a can. I bought a can and poured
it in, following the instructions on the can religiously. Huge clouds
of smoke came out with the Top Engine Cleaner in the combustion
chambers, presumablyfrom the carbon being burned off.

The tech also said to take it out and "drive it hard." I've had some
some other non-automotive chores that had to be done, so I've haven't
got around to the brisk drive yet. I will do that.
 
D

Dave Plowman (News)

Jan 1, 1970
0
Here are the results of my latest test:
October 4, 11:17 a.m.
Idle 538-540 rpm according to the test machine's display. (Should be
550)
HC, ppm: 15 mph: limit 55; actual 59 (fail)
HC, ppm, 25 mph: limit 100; actual 79 (pass)
CO, %, 15 mph: limit 0.22; actual 0.01 (pass)
CO, %, 25 mph: limit 0.32; actual 0.04 (pass
NO, ppm, 15 mph; limit 720; actual 136 (pass)
NO, ppm, 25 mph; limit 700; actual 188 (pass)
Overall test results: fail.

Confirms my earlier diagnosis. It's running weak. Check first for air
leaks anywhere in intake system and engine breathers. Only then check carb.
 
A

Ancient_Hacker

Jan 1, 1970
0
Beloved said:
GM sells this stuff called "Top Engine Cleaner."

My auto service guy says the stuff does little or nothing.

If the stuff really removed carbon, it would be used as oven cleaner,
less dangerous than lye.

Hmmm, too bad lye is hard on aluminum, maybe a can of "easy off"
would remove the Carbon?
 
H

Homer J Simpson

Jan 1, 1970
0
October 4, 11:17 a.m.
Idle 538-540 rpm according to the test machine's display. (Should be
550)
HC, ppm: 15 mph: limit 55; actual 59 (fail)
HC, ppm, 25 mph: limit 100; actual 79 (pass)

Did you change the oil before the test? That can make a lot of difference
I'm told.
 
J

James Sweet

Jan 1, 1970
0
What specific car are we dealing with? There's many newsgroups that
cater to just about every brand of car there is, and most have many
helpful folks on them.
 
B

Beloved Leader

Jan 1, 1970
0
Dave said:
Confirms my earlier diagnosis. It's running weak. Check first for air
leaks anywhere in intake system and engine breathers. Only then check carb.

Do you mean "lean?" That would be the terminology used in the States.
How do you account for the high intake manifold vacuum and the steady
needle on the vacuum gauge?

I posed the novella about my car at the Usenet group rec.autos.tech.

http://groups.google.com/group/rec....c3639/37efb17c8d47e636?hl=en#37efb17c8d47e636

or
http://tinyurl.com/lvb9n

Thanks again to everyone.
 
B

Beloved Leader

Jan 1, 1970
0
Ancient_Hacker said:
My auto service guy says the stuff does little or nothing.

I, too, am leary of the "engine rebuild in a can" chemicals, but the
old timers all swear by the stuff. It's mostly naptha.
 
D

Dave Plowman (News)

Jan 1, 1970
0
Do you mean "lean?" That would be the terminology used in the States.

Yes. Lower than normal CO and high HC is a classic symptom.
How do you account for the high intake manifold vacuum and the steady
needle on the vacuum gauge?

Do you know what the vacuum reading should be? However, if you're sure
there are no leaks, sound like the carb is faulty. Presumably being a late
type it has electronically controlled mixture and idle speed?
 
B

Beloved Leader

Jan 1, 1970
0
Dave said:
Do you know what the vacuum reading should be?

21" with the needle steady, not wobbling, is considered good. It had
been so long since I had last used one that I had to get on the
Internet to look up how to go about using one.

How to Use and Interpret a Vacuum Gauge
http://www.secondchancegarage.com/public/186.cfm
sound like the carb is faulty. Presumably being a late
type it has electronically controlled mixture and idle speed?

No. The Oldsmobile 5L/307 cid V8 is the last of the carbureted engines.
The carburetor (US spelling) has a throttle position sensor, but
everything about the carburetor's operation is mechanical, not
electronic, unless there's something I'm overlooking.

Thanks.
 
J

Jim Yanik

Jan 1, 1970
0
21" with the needle steady, not wobbling, is considered good. It had
been so long since I had last used one that I had to get on the
Internet to look up how to go about using one.

How to Use and Interpret a Vacuum Gauge
http://www.secondchancegarage.com/public/186.cfm


No. The Oldsmobile 5L/307 cid V8 is the last of the carbureted engines.
The carburetor (US spelling) has a throttle position sensor, but
everything about the carburetor's operation is mechanical, not
electronic, unless there's something I'm overlooking.

Thanks.

The only use for a throttle position sensor(TPS) is to electronically
control the engine. If only the ignition timing,which will affect
emissions.

Are you sure it's a carburetor and not just a throttle body with single
port injection? Is the TPS wired up? Maybe somebody put the wrong carb on.
 
Beloved said:
Dave Plowman (News) wrote:
Here are the results of my latest test:
Idle 538-540 rpm according to the test machine's display. (Should be 550)
HC, ppm: 15 mph: limit 55; actual 59 (fail)
HC, ppm, 25 mph: limit 100; actual 79 (pass)

CO, %, 15 mph: limit 0.22; actual 0.01 (pass)
CO, %, 25 mph: limit 0.32; actual 0.04 (pass)

NO, ppm, 15 mph; limit 720; actual 136 (pass)
NO, ppm, 25 mph; limit 700; actual 188 (pass)

Can you also post the CO2 and O2 readings? I won't know what they
mean, but someone will.
The only manual I have for the car is a Haynes manual, the one for
full-size GMs. There is a Haynes emissions manual, I think, but I don't
have it. I am within two miles of a Cadillac dealer and within four
miles of a community college with an automotive program. The community
college has a library of factory manuals and loads of CDs too. I'll be
able to pick a lot of brains if need be, but I want to do as much of my
own homework as I can first. Virginia's DEQ office is a local call.

I once glanced at the Haynes emissions manual and found it to be little
mroe than a rehash of the emissions chapters from other Haynes books.
It lacked the hundreds of pages of diagnostic tables found in the
Mitchell and factory manuals. That community college may not only let
you see the books but even fix your car at low cost, but don't be
surprised if they want to keep it for a few days.

Are you using only GM ignition parts -- AC plugs, wires, rotor, and
distributor cap? Some plugs don't substitute well, even when they're
supposed to, and trick wires (magnetic supression, as opposed to
resistive supression) can cause problems. I wouldn't even try AC
Rapidfires, simply because they're not factory original equipment.
Some brands of rotors and caps are made of bad plastic that cracks from
high voltage. I realize you changed all the vacuum hoses, but did you
check for vacuum leaks at the intake manifold gaskets and base of the
carburetor by spraying there with choke cleaner?
I did turn down the idle from its initial ~800 rpm to the specified
550. At this rpm, the engine sometimes stalls. I'll probably have to
turn it back up after I've passed the test.

Try injecting propane or choke cleaner into the air intake (leave air
filter and cover in place -- prevents fires in case of spit back) for a
few seconds. If the idle (set to about 550 RPM) smooths out (injecting
chemicals will make it speed up by as much as 200 RPM), suspect a
vacuum leak or a carburetor problem. The idle mixture solenoid has
been troublesome in some feedback carbs. I don't know if there's any
kind of idle speed regulation (throttle air bypass valve, throttle
kicker or motor), but a carburetor problem may be completely unrelated
to your high HC.

By the way, run the air conditioner compressor for at least 10 minutes
in a row each week, even during the winter, to keep the shaft seal from
drying out. You have a Freon R-12 system and don't want any of that
gas to leak out, and you don't want to convert to R-134a the wrong way
(cheap, quick conversions don't perform well and have high failure
rates).

I don't see the purpose of top engine cleaner here, and I'm surprised a
dealer mechanic would recommend it, at least not without first reading
out the CCC data stream during engine operation to find any
abnormalities (temperatures, barometric and manifold pressures, oxygen
sensor voltage, throttle position, fuel mixture solenoid duty cycle,
etc.).
 
D

Dave Plowman (News)

Jan 1, 1970
0
No. The Oldsmobile 5L/307 cid V8 is the last of the carbureted engines.
The carburetor (US spelling) has a throttle position sensor, but
everything about the carburetor's operation is mechanical, not
electronic, unless there's something I'm overlooking.

Then presumably has an adjustment for the idle mixture?
 
B

Beloved Leader

Jan 1, 1970
0
Jim said:
Are you sure it's a carburetor and not just a throttle body with single
port injection?

Totally, absolutely, positively, one hundred thousand, million,
billion, trillion percent. The carbureted 307 was last used in the
1990-model cars. In 1991, GM replaced it with the FI 305.
Is the TPS wired up?
Yes.

Maybe somebody put the wrong carb on.

Not a chance. The car has been in the family since new. It has the
factory carburetor.
 
B

Beloved Leader

Jan 1, 1970
0
Can you also post the CO2 and O2 readings?

No. The test equipment in use by the Commonwealth of Virginia does not
test for CO2 or O2. I've provided all that I've got.
I once glanced at the Haynes emissions manual and found it to be little
mroe than a rehash of the emissions chapters from other Haynes books.

I'm not surprised by that.
It lacked the hundreds of pages of diagnostic tables found in the
Mitchell and factory manuals. That community college may not only let
you see the books but even fix your car at low cost, but don't be
surprised if they want to keep it for a few days.

Oh, yes, I do get to look at the library. I'd also like to talk to some
of the instructors there. I still want to do the repairs myself, being
of the "if you want the job done right, you've got to do it yourself"
mentality. I also feel that I'd be a more meticulous mechanic than the
18- and 19-year olds taking the courses at the local CC.
Are you using only GM ignition parts -- AC plugs, wires, rotor, and
distributor cap?
No.


Try injecting propane or choke cleaner into the air intake (leave air
filter and cover in place -- prevents fires in case of spit back) for a
few seconds. If the idle (set to about 550 RPM) smooths out (injecting
chemicals will make it speed up by as much as 200 RPM), suspect a
vacuum leak or a carburetor problem.

I can try that, using an unlit propane torch. Bear in mind that the
idle's not rough, just low. Nonetheless, I find it hard to argue with
such a sterling reading on my vacuum gauge. For the record, I'm getting
my vacuum reading from a port that leads to the vacuum chamber for the
car's vacuum-actuated cruise control.
By the way, run the air conditioner compressor for at least 10 minutes
in a row each week, even during the winter, to keep the shaft seal from
drying out. You have a Freon R-12 system

Ice cold, baby. The real deal. The good stuff.
I don't see the purpose of top engine cleaner here, and I'm surprised a
dealer mechanic would recommend it, at least not without first reading
out the CCC data stream during engine operation to find any
abnormalities (temperatures, barometric and manifold pressures, oxygen
sensor voltage, throttle position, fuel mixture solenoid duty cycle,
etc.).

The oldtimers like the stuff. Remember that the CCC system is ancient,
being of the same vintage as 8088-based computers. It is way obsolete
compared to OBD II. There is no such thing as a CCC data stream. It
does not provide the sort of information you mention. My code scanner
does no more than short two terminals. By so doing, I can count flashes
on the "check engine light" that direct me to any suspect sensors. The
CCC system does not, as I have learned, make note of vacuum leaks.

I'm getting more responses at sci.electronics.repair and
sci.environment than I am at rec.autos.tech.

Thanks for writing, one and all.
 
B

Beloved Leader

Jan 1, 1970
0
Dave said:
Then presumably has an adjustment for the idle mixture?

Yes, but they're sealed. Federal law and so forth. I mean, no one would
ever know, but to get at the idle mixture adjustment screws, I'd have
to take the carburetor off and drill out the sealing plugs. There are
quite a few connections to the carburetor, so its removal is a major
undertaking.
 
D

Dave Plowman (News)

Jan 1, 1970
0
Yes, but they're sealed. Federal law and so forth. I mean, no one would
ever know, but to get at the idle mixture adjustment screws, I'd have
to take the carburetor off and drill out the sealing plugs.

On UK cars with this feature (for export to the US, etc) it's much easier
than that to remove the plug.
There are quite a few connections to the carburetor, so its removal is a
major undertaking.

Yup. Other thing to check for if the mixture is 'lean' at idle while
otherwise ok is air leaks round the buttefly spindle bushes. Smear some
grease round the outside for a temporary 'cure'. If the idle speed then
goes to normal you've got the reason.
 
H

Homer J Simpson

Jan 1, 1970
0
By the way, run the air conditioner compressor for at least 10 minutes
in a row each week, even during the winter, to keep the shaft seal from
drying out. You have a Freon R-12 system and don't want any of that
gas to leak out, and you don't want to convert to R-134a the wrong way
(cheap, quick conversions don't perform well and have high failure
rates).

What about http://www.duracool.com/ ??
 
J

Jim Yanik

Jan 1, 1970
0
Totally, absolutely, positively, one hundred thousand, million,
billion, trillion percent. The carbureted 307 was last used in the
1990-model cars. In 1991, GM replaced it with the FI 305.


Yes.

Well,what do you think the car does with that data?
 
B

Beloved Leader

Jan 1, 1970
0
Jim said:
Well,what do you think the car does with that data?

The data from the throttle position sensor is sent to the ECM, along
with the data from all the other sensors. The ECM uses that data to
control, in accordance with a look-up table in the ECM's memory, the
setting or position of a variety of actuators.
 
E

Eric Swanson

Jan 1, 1970
0
[email protected] wrote:

I can try that, using an unlit propane torch. Bear in mind that the
idle's not rough, just low. Nonetheless, I find it hard to argue with
such a sterling reading on my vacuum gauge. For the record, I'm getting
my vacuum reading from a port that leads to the vacuum chamber for the
car's vacuum-actuated cruise control.

You didn't mention the mileage on the engine. Consider that older engines tend
to have trouble with valve guide seals, which harden with age. A bit of extra
oil will seep past into the intake and may add to your HC emissions, especially
at low speeds when the throttle is almost closed. Also, your rings may be
allowing some oil into the cylinders. One final point to check, if you haven't
already done so, would be your PCV valve, which should close at high vacuum,
but may be so dirty or worn that it is not doing so, thus allowing excessive
amounts of gas into the intake manifold from the crankcase.
 
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