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Catalytic Converter


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#1
vol940

Posted 19 February 2005 - 11:20 AM

vol940

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Hi All,

Any idea to check the clogged/plugged Catalytic Converter without
dismantling it ?

--------------------------

#2
glock19

Posted 20 February 2005 - 03:12 PM

glock19

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If it's clogged, you can't unclogged it either, need to replace. To
check, I think can only compare it (layman's style) by parking it against
another similar car and 'feel' the pressure from the exhaust of both.
However if the cat is blocked, maybe the Lambda sensor can give some
pressure variance and light up one of the lamps on the dash ?

#3
kaminski

Posted 20 February 2005 - 05:55 PM

kaminski

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I think if you remove the o2 sensor and see a small improvement in
performance then it indicates a partially blocked cc...can I ask you why
you think its blocked?
On BMW's..I know from experience that if its blocked the car will go no
faster than 90/100mph...and after a long run and idling a whiff of sulphur
(bad egg smell) will emit from the exhaust every now and then.In
addition,fuel consumption increases.
Fuel consumption increse can also be caused if the cc has been
poisoned,ie,contaminated by coolant leakages into the exhaust system,if
you remove the cc and see white beach type sand in it then its been
poisened!If its sooty and black then chances are its partially blocked.
Its worth noting that some fuel additives accelerate/shorten the life
span of a cc,as do certain chemicals found in various engine sealants and
cements.

#4
vol940

Posted 22 February 2005 - 12:29 AM

vol940

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Glock19,

Your idea is very original, the problem is I am not so sensitive enough
to "feel" the difference pressure from the exhaust ... hahahah ... sorry
laaah I am old enough ... need other sensitive ppl to help me .... Smile

Glock, I think that lambda sensor has nothing to do with the pressure,
just measure the oxygen concentration in the exhaust gas then comparing
with the ambient oxygen concentration. This difference oxygen
concentration which create the difference potential and send to ECU.

--------------------------------------

kaminski,

Reasons : FC is getting higher .... loss power at 3000 to 4000 rpm.

Your idea to remove the oxygen sensor gives me some inspirations, yeah
remove the O2 sensor and plugged with Pressure Gauge.

Constraints :

1. Accessibility the O2 Sensor on 940
2. Need special tool to open
3. No Data for Maximum Back Pressure.

Anyway, many thanks for your ideas, I'll try to find out some methods to
test it.

#5
kaminski

Posted 22 February 2005 - 01:42 AM

kaminski

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Found this at
swedish bricks.com.

Using a Fluke Digital Multimeter with the 80T-IR/E Extended Range
Temperature Probe, you can easily and quickly assess catalytic converter
efficiency. For this test, first run the engine until the engine is warm
and stabilized. (For engines with electric cooling fans, let them cycle a
few times prior to the test) Then shut off the engine and disconnect a
spark plug wire on one bank of cylinders. (Note for V engines: If there
are dual converters, you will need to perform this procedure on each bank
of cylinders.
Restart the engine and block the throttle to maintain 1000 RPM with the
one cylinder not firing. Measure the inlet temperature of the converter
and compare it to the outlet temperature. You should see a differential
of 50 degrees F. or more if the converter is working properly. If the
temperatures are less than 50 degrees apart, then the converter needs to
be replaced. Before replacing a converter, be sure to determine why it
may have failed. If it is a very high mileage vehicle, it is probably
just expired. If it is low mileage, you should perform a thorough check
of the vehicle to determine the cause. For normal engines with a
misfiring cylinder at 1000 RPM, you can expect that the temperatures
observed will be in the 600 to 900 degrees F. range

To make it quicker diagnosis why not use one of those point and record
digital thermometers! If you know someone at Tractors Malaysia I am sure
you could borrow there Cat digital thermometer!

#6
vol940

Posted 22 February 2005 - 02:02 PM

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kaminski,

Woouuw ... bro... that is very high-tech ... laaaaar!!!

FYI, mine has already 380k km.

It seems that this method is to check wether CC still function properly
or already damaged (kaput), coz the different temperature in the inlet
and outlet CC indicates that there is still exhaust gas conversion
(combustion) in the CC.

The clogged CC (due to carbon deposit) will effect on back pressure, so
the methods shall be directed/focused on pressure measurement. So just
simple measurement on pressure, we could identify that the CC clogged or
not.

It is ofcourse that the presence of carbon deposit will reduce the
functionality of the CC (also effecting the back pressure) and the
checking method which you described above is very usefull.

BTW, thanks for your helpfull information, I'll keep in my maintenance
book.

#7
vol940

Posted 23 February 2005 - 09:59 AM

vol940

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Kaminski, glock19,

Bingo, got already the simple method to check clogged CC without removing
it.

1. For vehicles equipped with Turbo/Boost Gauge : Start the engine and
wait up to 10 minutes. The Turbo needle gauge will stabilize at 10
o'clock. Then increase the RPM up to 2500, If the boost gauge needle
remains at 10 o'clock, means that the CC is not clogged. But If the boost
needle shift to 10.30 to 11.00 o'clock (on 940), means that the CC is
already clogged.

2. For N/A vehicles, use Vacuum Gauge connected to vacuum line/hose on
intake manifold (Brake Booster or PCV or Pressure Regulator Vacuum Line).
Start the engine and let idle for 10 minutes. The vacuum gauge will
stabilize at 21 or 20 or 19 Inche Hg. Increase the RMP up to 2500, when
the vacuum gauge reading remains at 21 or 20 or 19 Inche Hg, the CC is
still in good condition. But if the vacuum gauge indicates 15 Inche Hg or
less, then the CC is already clogged.

When CC clogged, the exhaust back pressure increased, part of exhaust gas
will enter into combustion chamber, reducing the intake Volumetric
Efficiency (VE) - less air intake enter into combustion chamber, decrease
the vacuum as a result. Big Smile

#8
vol940

Posted 23 February 2005 - 10:05 AM

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Try to remove CC today and replace with 2.5" straight pipe from DP to
First Silencer ..... very sorry not to replace back with CC, the badget
is already for TT Kuantan.Crying

#9
cap48

Posted 23 February 2005 - 11:13 AM

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Can refit when the budget allows mah! Hmmm...another flying 940 for the
Kuantan trip???Approve

#10
vol940

Posted 23 February 2005 - 11:08 PM

vol940

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cap48,

Not flying 940, dino turtle 940 mah !!!, after fixing the straight
exhaust pipe, tried to clean the carbon deposit in combustion chamber,
the un-noticeable leakage on exhaust (turbo - manifold joint) became
visible, another problem bro...

Anyway, after removing the CC, acceleration boleh tahan laaaah ... laju
skit but FC remains the same due to leakage on turbo-manifold joint. To
compesate the running rich condition, I put another air cold intake
(small size) connected to PCV to dilute the fuel vapor before entering to
intake manifold, yang ni ... boleh tahan ... senang potong kereta hehehe.