1993 240 high NOX

Hi there !! I just managed to pass the NYS inspection on my new (to me) 245
w/182k miles. I took it last Saturday and it failed the NOX, the mechanic
suggested a tune up, I then replaced the following items:

Spark plugs (bosch platinum), spark plug wires (bosch), distributor cap,
rotor, air filter, flame trap, hose from flame trap to breather box, hose
from flame trap to intake manifold, cleaned brass nipple at manifold. Put 12
gallons of 93 octane fuel with a 12 Oz bottle of Techron, to clean
injectors, did a lot of highway driving (65-80 MPH), used all the fuel, put
another 12 gallons and another bottle of Techron, and took the test. Barely
passed, this are the results:

HC CO NOX
Before tune up .64 ppm 6.51 ppm 2.46 ppm
After tune up .42 ppm 3.50 ppm 1.99 ppm
Max Limit .80 ppm 15.00 ppm 2.00 ppm

What should I look at now to lower NOX ?

The car was at normal operating temperature at the test. The car sat for a
while before I bought it.

Any help would be appreciated.

Arnold

arnold_perez13 at verizon dot net

sorry for the spam kill

 

This is from the IPD catalogue http://www.ipdusa.com/ , something every 240
owner should have on their coffee table.

High NOX, you could have:

Lean Mixture
Timing too far advanced on 1988 and older cars
EGR system malfunction like:
Bad Valve
Broken Vacuum Line
Plugged Pipe
Bad Vacuum Controller
Engine/cat not fully warmed up
Bad Catalytic Converter

Good Luck,

 

The cat converter is the most expensive item on the list, but it has gone
more miles than its expected life.

 

-- besides carb adj., try checking/replacing the carb-to-manifold
gasket and the manifold-to-head gasket as well as any other vac lines
in the manifiuld after the carb. Even a leaking vac canister. An air
leak there will cause lean mix.

--easily checked, and even retarding it JUST A BIT before the test
can help.

--The smog test shop should check this- easy enoiugh to do by just
disconnecting the vac line and connecting a hand vac pump.

--not a problem here in this case

A muffler shop can check this, but if you have a pyrometer or an
infrered non-contact thermometer, try checking the temps at the header
pipe into the cat, the cat temp, and the exhaust pipe temp at the exit
of the cat. It should be substantially hotter going out than going in.
One way to check the cat's function.


from Randy & Valerie
__ __
\ \ / /
\ \/ /
\__/olvo
1993 960

 

From what you state it would seem that the converter has seen better days
look in to replacing it

--
"*-344-*Never Forgotten"
Is for the New York City fireman who lost their lives on September 11,2001.
The official count is 343, but there was also a volunteer who lost his life
aiding in the initial rescue efforts. And I will never forget them as long
as I live,
nor should any American.
"Mow Green"

 

I have used a gasoline additive called RXP and have had wonderful results.

 

Yesteday I cleaned the throttle body assy, and the idle solenoid, installed
new gasket on the TB to manifold, and it idles better, I have another year
before I take it to emmissions again, will see about having a pre-cat and
post cat reading, thanks to all who posted.

Arnold

 

You can buy "limited lifetime warranty " direct fit fit converter at
places like Autozone in for around $100.00 .

 

Also, the cat can cool off enough just waiting a few minutes for the
test to actually start. In Ontario, our test aborts as soon as the test
program determines that the car will pass. Often, this is as the cat is
warming up, so one of the pollutants is very close to the limit, but
heading down. This scares people into thinking the car will not pass
next time.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)