94 Accord Wagon Failed Emmissions - Running Hot?

My 1994 Accord Wagon, 172k miles, failed emissions for NOX. I am told that
my combustions chambers is running "hot" but the Catalytic converter may
still be ok. One suggestion is to add some alchol before trying the test
again and also to make sure the engine is a cool as possible. Someone
else<g> has told me to get some magic additive that is sold in auto parts
stores to fix my problem...another genius suggests a run of Gum out.

I am willing to spring for a new catalytic converter if it fails a retest
and if that will certainly fix my problem. Can anyone explain what my
problem is, in layman's terms, and the validity of some of the helpful
suggestions from my buddies?

Thanks,

Mark

 

You may fail on high HCs. Don't put crap in your gas to mask an unrelated
problem. Find the real problem first.

Prep the car with long, hard run on the highway immediately beforehand to
make certain the cat is up to temp.

Chevron Techron injector cleaner isn't a bad idea, but not right now.

DO NOT replace that cat. It is the LEAST likely culprit.

Your problems range from defective EGR to overly advanced timing to a lean-
biased O2 sensor to gummed-up injectors to daily variance in the emissions
testing equipment (up to 400% variance per day).

http://tinyurl.com/axsuo

http://www.asashop.org/autoinc/oct2004/techtips.cfm

 

check the ignition timing, and egr.

 

Thanks. Not very comfortable with dumping stuff in the tank... The dealer
did check the car out after the failure, would their diagnositics
highlighted any of these other items?

Mark

 

Depends how competent they are in diagnosing failures. Dealers are not
usually the best place to bring an older car for diagnosis, since they
specialize in the new stuff.

Also, you have not posted any of your actual numbers (or the limits in your
area), so it's difficult to help you further.

If you book a retest at a different facility, or at the same place a week
later, you may pass without any work done at all to your car. Seriously. If
you fail again, then more attention is needed. Until then I would do
nothing.

Check out my numbers:
http://www.tegger.com/hondafaq/misc/91_integra_emissions.html
See the June 2003 NO numbers? I did absolutely nothing except oil changes
and the usual maintenance between then and 2005, and NO plummetted.

 

The numbers are:

HC (PPM)
Limit 136
Emmisions 7
Pass

CO(%)
Limit .73
Emissions .02
Pass

NOx (PPM)
Limit 1591
Emissions 2186
Fail

Does this help at all? I am certainly going to try again at another place
after a long ride there.

Thanks,

Mark

 

You are running WAY lean according to these numbers.

First step: Take the car in for a retest with NO work done. You have a
better than even chance of passing.

If it fails second time around, check for:
1) A leak in the exhaust before the cat
2) Ignition timing too far advanced
3) EGR valve not opening
4) Lean-biased O2 sensor (replace to check).

 

i agree with tegger you're /way/ lean. run a couple of tanks of
injector cleaner through - make sure you do some extended /full
throttle/ hills as part of that. if that doesn't work, go for a new
oxygen sensor. don't re-test while you still have injector cleaner in
there.