Function of EGR Valve and Catalytic Converter used in 1991 Camry V6

[Vince]

My vehicle failed NYMA emissions inspection criteria with the
following emission inspection test result readings:

HC= 0.47 gpm (limit 0.80)
CO= 17.82 gpm (limit of 15.00)
NOx= 0.63 gpm (limit 2.00)

After replacing the EGR valve, the emissions inspection test result
readings were:

HC= 0.62 gpm, CO= 31.48 gpm, and NOx= 0.51 gpm.

The catalytic converter was replaced next, and the emissions
inspection test readings changed:

HC=2.93 gpm, CO=93.01 gpm, and NOx=0.22 gpm.

Can anyone explain why have the HC and the CO emissions inspection
test readings become progressively worse, after replacing these
(expensive) emissions control items?

Does a cat converter, specifically, the Toyota P/N 18450-62050, as
used in my 91 Camry V6, function to reduce HC, CO, and NOx emissions,
or is the function of the cat converter to filter and reduce only HC
and CO gases ? (Some cat converters do not handle NOx gasses.)

Does an EGR valve, specifically, the Toyota P/N 25620-62020, as used
in my 91 Camry V6, function to help reduce HC, CO, and NOx exhaust
gas emissions, or does a properly functioning EGR valve help to reduce
NOx gases only ?

Vehicle is 1991 Toyota Camry Sedan 2WD, V6-2507cc 2.5L DOHC (2VZ-FE)
engine, driven within the NYC metro area (Long Island). .

I do not know what "gpm" units are, but is 17.82 gpm, which exceeds
the test criterion limit by 2.82 gpm , a significant failure? Of
what component(s) ?

Any comments?

TNX.

[m Ransley]

You may want to have another test done you cant be sure of accuracy. How
much oil do you consume, When did you do plugs, wires, ck timing,
pollution equipment, etc , did a mechanic do the work. Did he use modern
calibrated test equipment .

[Vince]

Post by m Ransley
You may want to have another test done you cant be sure of accuracy. How
much oil do you consume, When did you do plugs, wires, ck timing,
pollution equipment, etc , did a mechanic do the work. Did he use modern
calibrated test equipment .

TNX for your info.

Work was done at repair shop of a local Toyota dealership.
This 1991 vehicle had 58,129 miles two weeks ago at time of emission
inspection (prior to replacing the EGR valve).

Plugs, PCV valve, Air Filter, Coolant were last replaced (as part of
dealership's 30,000 mile maintenance) when vehicle mileage was 35,347
miles in NOV 1996.

There is no indication of burning oil. Vehicle is driven on Long
Island (NYMA).

[m Ransley]

I have a 91 and my numbers at 91000 are way below maxiums I use 1 qt in
maybe 5000. You must consume some oil normaly yes. Either the test ,
mechanic, bad equipment or another problem is giving you trouble if
your motor is truely in good shape an using normal oil consumption.

Mechanics put cars on a tune up "scope" that would at the dealer show
you if you have any problems with combustion. What were the results of
that. Im sure you told the dealer of your EPA failure so testing by him
would be normal as he could sell you more repairs till you passed on his
machine. Maybe his stuff wasnt OEM But i cant answer the increase and
if its normal.

Point is the dealers mechanic may also be a hack since you brought it
in to pass.. Mark-Tag replaced parts and go back. But find out what
they want to do as what was done was probably unessecary and may have
ripped you off . But im no mechanic my point is the car failed and you
payed to make it pass

[Vince]

Post by m Ransley
I have a 91 and my numbers at 91000 are way below maxiums I use 1 qt in
maybe 5000. You must consume some oil normaly yes. Either the test ,
mechanic, bad equipment or another problem is giving you trouble if
your motor is truely in good shape an using normal oil consumption.
Mechanics put cars on a tune up "scope" that would at the dealer show
you if you have any problems with combustion. What were the results of
that. Im sure you told the dealer of your EPA failure so testing by him
would be normal as he could sell you more repairs till you passed on his
machine. Maybe his stuff wasnt OEM But i cant answer the increase and
if its normal.
Point is the dealers mechanic may also be a hack since you brought it
in to pass.. Mark-Tag replaced parts and go back. But find out what
they want to do as what was done was probably unessecary and may have
ripped you off . But im no mechanic my point is the car failed and you
payed to make it pass

Actually, a NY State DMV waiver was issued, because the vehicle failed
emissions a third time, following replacing the cat converter ! This
fact I found out only at the time of picking up my "ready" car....

Your point is well taken about oil consumption. I should have said
that there is no indication of oil burning from exhaust pipe. The
vehicle is driven less than 5000 miles each year, and it has been
routine for me to have oil & filter changed at time of annual NYState
inspections. In between, at the random times that I check the oil
level dip stick, there has been no abnormal oil level indicated.

I am not a mechanic and have been relying on the dealership repair
shop since buying this Camry for repair service and also for service
on my wife's 93 Corolla. It has been years since I did minor
maintenance (oil, filters, PCV valve, wires) on my '66 Mustang 289 or
my '71 Ford Torino.

Having gone over the papers here this morning, I see that the PCV
valve and air filter are overdue for replacement (approximately 22,000
miles driven since those were replaced). I will look into doing that
myself, if I can locate the PCV valve, and I have an idea of where the
air filter is located.

There was no mention of any "scope test results". No computer repair
codes were reported. Only (an inaccurate) report that reason for the
initial Emission Inspection failure was excessive NOx. (I finally
obtained the Inspection Rejection Notice from their repair shop
yesterday by FAX. It shows that the CO level exceeded the test
criterion limits prior to replacing the EGR valve and that the NOx
levels never exceeded the test limit criteria). Their diagnosis
report was that a bad EGR valve was found. I was advised after the
EGR valve replacement that the catalytic converter needs to be
replaced.

m, is your '91 a V6 engine? What area are you located within?

Can you / anyone point me to information about the repair codes for
this 2VZ-FE V6 engine ?

TNX.

[j***@gmail.com]

Did you ever find out what the problem was?
I have a 91 having the same problem but the carbon monoxide it way up at 115.3 and its suppose to be 12.00 the nox is way under.
with new cat and was going to do egr and also the regulator. have already done the pcv.
now the car has 86k miles and has spent its life in the garage since noone can figure it out.

Post by Vince

Post by m Ransley
I have a 91 and my numbers at 91000 are way below maxiums I use 1 qt in
maybe 5000. You must consume some oil normaly yes. Either the test ,
mechanic, bad equipment or another problem is giving you trouble if
your motor is truely in good shape an using normal oil consumption.
Mechanics put cars on a tune up "scope" that would at the dealer show
you if you have any problems with combustion. What were the results of
that. Im sure you told the dealer of your EPA failure so testing by him
would be normal as he could sell you more repairs till you passed on his
machine. Maybe his stuff wasnt OEM But i cant answer the increase and
if its normal.
Point is the dealers mechanic may also be a hack since you brought it
in to pass.. Mark-Tag replaced parts and go back. But find out what
they want to do as what was done was probably unessecary and may have
ripped you off . But im no mechanic my point is the car failed and you
payed to make it pass

Actually, a NY State DMV waiver was issued, because the vehicle failed
emissions a third time, following replacing the cat converter ! This
fact I found out only at the time of picking up my "ready" car....
Your point is well taken about oil consumption. I should have said
that there is no indication of oil burning from exhaust pipe. The
vehicle is driven less than 5000 miles each year, and it has been
routine for me to have oil & filter changed at time of annual NYState
inspections. In between, at the random times that I check the oil
level dip stick, there has been no abnormal oil level indicated.
I am not a mechanic and have been relying on the dealership repair
shop since buying this Camry for repair service and also for service
on my wife's 93 Corolla. It has been years since I did minor
maintenance (oil, filters, PCV valve, wires) on my '66 Mustang 289 or
my '71 Ford Torino.
Having gone over the papers here this morning, I see that the PCV
valve and air filter are overdue for replacement (approximately 22,000
miles driven since those were replaced). I will look into doing that
myself, if I can locate the PCV valve, and I have an idea of where the
air filter is located.
There was no mention of any "scope test results". No computer repair
codes were reported. Only (an inaccurate) report that reason for the
initial Emission Inspection failure was excessive NOx. (I finally
obtained the Inspection Rejection Notice from their repair shop
yesterday by FAX. It shows that the CO level exceeded the test
criterion limits prior to replacing the EGR valve and that the NOx
levels never exceeded the test limit criteria). Their diagnosis
report was that a bad EGR valve was found. I was advised after the
EGR valve replacement that the catalytic converter needs to be
replaced.
m, is your '91 a V6 engine? What area are you located within?
Can you / anyone point me to information about the repair codes for
this 2VZ-FE V6 engine ?
TNX.