high nox- won't pass 1988 240

Hi, Anyone have any ideas, I have a new MAS, had the the intake side
cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
the O2 sensor, the CO and HC are as low as could be for that car. The
car runs great (only 74,000 miles) Any thoughts would be greatfully
appreciated.

thanks

Ed wrote:
> Hi, Anyone have any ideas, I have a new MAS, had the the intake side
> cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
> the O2 sensor, the CO and HC are as low as could be for that car. The
> car runs great (only 74,000 miles) Any thoughts would be greatfully
> appreciated.

I've heard a rumor from a mechanic buddy of mine that some people have
had to install a second cat to get NOX down.

-K

Kelsey Cummings wrote:
> Ed wrote:
>> Hi, Anyone have any ideas, I have a new MAS, had the the intake side
>> cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
>> the O2 sensor, the CO and HC are as low as could be for that car. The
>> car runs great (only 74,000 miles) Any thoughts would be greatfully
>> appreciated.
>
> I've heard a rumor from a mechanic buddy of mine that some people have
> had to install a second cat to get NOX down.
>
> -K

Does that model have the Chrysler knock generator on it?
If so, google it... there are ways to make it pass.

In article <(E-Mail Removed). com>,
(E-Mail Removed) says...
> Hi, Anyone have any ideas, I have a new MAS, had the the intake side
> cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
> the O2 sensor, the CO and HC are as low as could be for that car. The
> car runs great (only 74,000 miles) Any thoughts would be greatfully
> appreciated.
>
> thanks
>
>
If the vacuum hose to the vcuum transducer on the side of the ignition
control unit is plugged the the unit is forced to go to a conventional
advance curve. The NOx will be greatly reduced.

On a similar note--exhaust emissions arer modified in two ways via
catalytic conversion. The first stage of conversion is the oxidation
stage where HC and CO are oxidized to form CO2 and water. The second
stage or reduction stage is designed to pull O off the NOx radicals to
form N2 and O2. Volvo has done this for years with a three way catalyst
built on a single monolithic honeycomb substrate inside the converter
housing. By its design in 1978, the reduction of NOx is less than
efficient, however it more than met the standards of the time that were
primarily concerned with CO and HC emission reduction. As time passsed
the NOx component got more and more regulation attention and the
standards tightened pushing the design to its limits. By the end of the
red motor run as much tinkering with the rare earth metals plated to the
substrate had reached its absolute limit. Consequently the later you get
in the production run the more likely you will encounter NOx emissions
failures during testing. The best strategy is to make sure the oil in
the motor is fresh and the converter is good and hot (run for 30 minutes
or more in mixed traffic conditions) before any emissions test is run.

Bob
--
The goal when driving is to miss the maximum number of objects.

Clay wrote:
> Kelsey Cummings wrote:
> > Ed wrote:
> >> Hi, Anyone have any ideas, I have a new MAS, had the the intake side
> >> cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
> >> the O2 sensor, the CO and HC are as low as could be for that car. The
> >> car runs great (only 74,000 miles) Any thoughts would be greatfully
> >> appreciated.
> >
> > I've heard a rumor from a mechanic buddy of mine that some people have
> > had to install a second cat to get NOX down.
> >
> > -K
>
> Does that model have the Chrysler knock generator on it?
> If so, google it... there are ways to make it pass.

Well it has the chrysler ecu so I will assume it has their knock
sensor....

User wrote:
> In article <(E-Mail Removed). com>,
> (E-Mail Removed) says...
> > Hi, Anyone have any ideas, I have a new MAS, had the the intake side
> > cleaned by a knowledgeable volvo guy, the cat is relatively new, as is
> > the O2 sensor, the CO and HC are as low as could be for that car. The
> > car runs great (only 74,000 miles) Any thoughts would be greatfully
> > appreciated.
> >
> > thanks
> >
> >
> If the vacuum hose to the vcuum transducer on the side of the ignition
> control unit is plugged the the unit is forced to go to a conventional
> advance curve. The NOx will be greatly reduced.
>
> On a similar note--exhaust emissions arer modified in two ways via
> catalytic conversion. The first stage of conversion is the oxidation
> stage where HC and CO are oxidized to form CO2 and water. The second
> stage or reduction stage is designed to pull O off the NOx radicals to
> form N2 and O2. Volvo has done this for years with a three way catalyst
> built on a single monolithic honeycomb substrate inside the converter
> housing. By its design in 1978, the reduction of NOx is less than
> efficient, however it more than met the standards of the time that were
> primarily concerned with CO and HC emission reduction. As time passsed
> the NOx component got more and more regulation attention and the
> standards tightened pushing the design to its limits. By the end of the
> red motor run as much tinkering with the rare earth metals plated to the
> substrate had reached its absolute limit. Consequently the later you get
> in the production run the more likely you will encounter NOx emissions
> failures during testing. The best strategy is to make sure the oil in
> the motor is fresh and the converter is good and hot (run for 30 minutes
> or more in mixed traffic conditions) before any emissions test is run.
>
> Bob
> --
> The goal when driving is to miss the maximum number of objects.

Bob, excellent information, thank you. This is what I've done already:
It failed on the first test (29.usd) I got one free retest, so I got
it up on the highway, drove around town a bit, took it in and got it
down to 3.65 grams per mile-- unfortunately the limit is 3.00, that
failed me, put a can of "guaranted to pass" and a couple of tanks of
premium did the same routine and got it down to 3.05 that cost 29.usd,
had the mechanic do the aforementioned, (75.usd) and just drove it
from his place to the emissions tester and it was up to 4.10 gpm
another 29. usd, the same thing happened at the last testing and the
garage put a new cat in it..... that was only 15,000 miles ago, this is
ridiculous.

ed

In article <(E-Mail Removed). com>,
(E-Mail Removed) says...

> Bob, excellent information, thank you. This is what I've done already:
> It failed on the first test (29.usd) I got one free retest, so I got
> it up on the highway, drove around town a bit, took it in and got it
> down to 3.65 grams per mile-- unfortunately the limit is 3.00, that
> failed me, put a can of "guaranted to pass" and a couple of tanks of
> premium did the same routine and got it down to 3.05 that cost 29.usd,
> had the mechanic do the aforementioned, (75.usd) and just drove it
> from his place to the emissions tester and it was up to 4.10 gpm
> another 29. usd, the same thing happened at the last testing and the
> garage put a new cat in it..... that was only 15,000 miles ago, this is
> ridiculous.

Well then, just put something solid in the vacuum hose going to the
vacuum capsule to stop it up, reconnect it so that it looks correct and
retest. We don't use the I/M 240 test here, but the two speed dyno test
for preOBDII cars like yours generate %CO, HC ppm and NOx ppm. Typically
on a 240 in good operating condition you would see CO% ~0.1%, HC 20-30
ppm and NOx arouund 1200ppm. After changing the advance curve by
plugging the vacuum tube thereby restricting ignition advance to about
33*BTDC max, the NOx falls to 400-600ppm depending on the condition of
the converter. The fail spec for NOx differs for each year here but
hovers right around the 1100-1400ppm range. I would assume that your
results should a similar percentage reduction in gms/mile.

The only way to reduce NOx formation is to cool the combustion
temperature. The two methods most commonly used are to reintroduce
exhaust gas (EGR) or to retard the ignition timing.With the Chrysler/MPG
system, as the car starts to move, first retartds the timing to 5*BTDC
and then rapidly advances the timing to a maximum of 52*BTDC and retards
the timing across the board in 19* steps per engine revolution once the
knock sensor "hears" a ping. Once the ping stops it advances the timing
again in 2* increments per revolution until it reoccurs, then repaeats
the process. Consequently the ignition advance and combustion
temperature remain artificially high, the motor wrings out marginal
extra HP from the gasoline and just pukes NOx. If you were to side by
side test a 1982 with Bosch ignition (standard advace curve) with your
car the '82 with higher compression and much less efficient fuel
injection, would have slightly higher CO and HC numbers but even with
essentially the same converter as yours had originally would produce
passing NOx numbers.

Bob

--
The goal when driving is to miss the maximum number of objects.

User wrote:
> Well then, just put something solid in the vacuum hose going to the
> vacuum capsule to stop it up, reconnect it so that it looks correct and
> retest.

fyi, if you choose to 'experiment' by *temporarily* plugging the line
(because we all know that to operate the vehicle when modified that way
is illegal in many states;') be sure the plug seals completely. I
'tested' this once and the plug leaked. Darn near rattled the pistons
out of it...

In article <M1gkg.50677$(E-Mail Removed)> ,
(E-Mail Removed) says...
> User wrote:
> > Well then, just put something solid in the vacuum hose going to the
> > vacuum capsule to stop it up, reconnect it so that it looks correct and
> > retest.
>
> fyi, if you choose to 'experiment' by *temporarily* plugging the line
> (because we all know that to operate the vehicle when modified that way
> is illegal in many states;') be sure the plug seals completely. I
> 'tested' this once and the plug leaked. Darn near rattled the pistons
> out of it...
>
If the plug leaks then it works ;ike the delay valve that was initially
put in the line. If the engine rattled then you had either poor fuel
delivery from the injectors or the engine was running at too high a
temperature while the knock sensor was not sending the proper signal to
the fuel control unit. Plugging the advance signal hose does nothing
more than force the control unit to behave as it it were a later EZK
system minus the fancy individual cylinder retard control.

Bob
--
The goal when driving is to miss the maximum number of objects.

Heh Bob, I did your fix, you're a genius, it worked like a charm.

Ed
User wrote:
> In article <M1gkg.50677$(E-Mail Removed)> ,
> (E-Mail Removed) says...
> > User wrote:
> > > Well then, just put something solid in the vacuum hose going to the
> > > vacuum capsule to stop it up, reconnect it so that it looks correct and
> > > retest.
> >
> > fyi, if you choose to 'experiment' by *temporarily* plugging the line
> > (because we all know that to operate the vehicle when modified that way
> > is illegal in many states;') be sure the plug seals completely. I
> > 'tested' this once and the plug leaked. Darn near rattled the pistons
> > out of it...
> >
> If the plug leaks then it works ;ike the delay valve that was initially
> put in the line. If the engine rattled then you had either poor fuel
> delivery from the injectors or the engine was running at too high a
> temperature while the knock sensor was not sending the proper signal to
> the fuel control unit. Plugging the advance signal hose does nothing
> more than force the control unit to behave as it it were a later EZK
> system minus the fancy individual cylinder retard control.
>
> Bob
> --
> The goal when driving is to miss the maximum number of objects.