i had to take my truck to have the emissions done and it failed the NOx ppm any help will be grateful thanks Billy



the truck is a 94
22re 4x4 5 speed
265xxx miles
i dont know much about the truck as i just got it not to long ago

the test is the ga emissions
test results
25/25 test
reading allowed
hc ppm 110 164
co% 0.35 1.84
NOx ppm 1595 1047 fail
rpm 2565 3000
co+co2% 15.0 6.0


50/15 test
reading allowed
94 168
0.34 1.42
1461 1146 fail
2850 3000
15.0 6.0

 

do i basic tune up

 

replace cat converter.Tune up wont help nox.Nox only forms in combustion chamber above 2500 degrees.You got your moneys worth out of a 265k converter,new one is about 90 bucks from summit.

 

had to go thru smog 2 months ago. failed with high Nox. the smog mechanic who fixed it, replaced the egr modulator, not the egr itself, but the plastic bit before it. knock the Nox down by 80%. think that part cost 15-20$

 

there you go..

 

pull the egr off and clean it out with carb cleaner

 

might aswell get ya a new o2 sensor.. thats what sends signals to the ecu..

 

NOx failed both low and high speed tests. Not likely to be EGR related due to the low speed failure.

One can rather safely rule out fuel mixture, and consequently O2 sensor operation, due to the HC and CO results: a lean mixture should be low on HC and high on CO, but the readings were 110 / 164 and 94 / 168 for HC (low/high speed) and 0.35 / 1.84 and 0.34 / 1.42 for CO%. Both readings suggest good, consistant air-fuel ratio control and combustion effeciency.
.
Either too much ignition advance causing high combustion temps or failing catalytic converter are the likely culprit(s).

 

smarty pants

 

OK Abe, I'm gonna say it, and know you will hate it...



Try a Seamfoam treatment first!!! If you have crap built up in your CAT, Seafoaming it can break up, dry up, and melt some of that goo out of there; it did on my 4 rnr, and my caprice.

 

ya, seafoam is good stuff,

a few year back i found a junk push mower on the side of the road brought it home started it would stay running... dumped some seafoam in the carb.. it woke up from a sputer and ran like a wild animal.. mower sold for a quick 50 bucks

 

Check igntion timing. If the EGR is working correctly, you need fresh cats. New convertors clean nicely. Christ, you got 265k+ on it.

 

How does seafoam get into the cat to clean it if it's supposed to all burn up in the combustion process?

 

We used to use this stuff called RUNRIGHT that was sucked in by a vacuum hose at idle and really woke up engines by cleaning the internals. But is smoked like crazy till it burned off. The neighbors loved it.

 

most cat converts are only good for about 70k or seven years..

 

ya there will be little smoke until burns off,

all the smoke means its actually working (cleaning)

 

...to Dupermandave; not sure exactly how, but it does. I have seen it pull both water/moisture, and goo out of my pipe, I think it is a combo of the fumes of the isopropyl, and another agent, that when heated up, do the same thing inside your CAT, as what happens in your engine/fuel injectors. I am not sure that isopropyl turns into a gas when burnt, so it will get into the CAT in whatever state it is, and start to breakdown and dry out the chunks that are in there, anyway.

 

thanks guys i replaced the cat and it will be tested again tomorrow so we will see if that fixes it

 

thanks for the info. I use seafoam about every 6 months. It's good stuff.