I recently purchased a 2003 Acura TL. I took it in for emissions testing and the results show that i failed due to high levels of HC and CO. HC level was 302.5(72 allowed) and CO level was 11.78(0.4 allowed).

I took the car to autozone to see if there were any codes to help diagnose the problem. The only code that came up was p1399. I then changed the plugs (which it needed anyway) and ran a bottle of sea foam through hoping for an easy fix.

It was about 2 fill-ups later before i found the time to have it retested. The results of the second test showed the HC level at 361.6 and CO at 12.49, both higher than before.

There are 130k miles on the vehicle. It is very clean inside and out and appears to have been well maintained. It looks and runs like new. There is no rough idle, no hesitation and plenty of power! The check engine light is not on. I have spent a lot of time reading through these forums and I see that there are many possible causes for this error code and emission levels, however all state that their car is running rough, or their check engine light is on.

I was wondering if anyone has ran across this situation and has any advice on where I should start to help me save time and money.

Thank you.

 

I failed to mention that the one and only problem with the car is that the gas mileage is terrible. I barely get 230 miles to the tank.

Please let me know if there is any other information you may need.

 

Hey Capnwork, while I'm no expert with emissions as our local inspections don't require them. Lucky me ! Anyways.....welcome and good luck with resolving your problem.

It seems strange that your car is not displaying a CEL light, especially if Autozone came up with the P1399 code. This is for a random misfire. Many things can cause this such as a worn coil, restricted injectors, vacuum leak, loose wiring connection, valve lash, dirty TB intake, O2 sensor on cat, etc....!

You stated that it runs smoothly, but gets poor gas mileage. Something is more than likely on the edge and the computer is compensating by running rich. If you just recently purchased the car, see if you can find out where it was last tested. I wonder if the CEL light is even functional ?

 

Thanks for your reply. The previous owner lived in a county that didn't require emissions testing, so unfortunately there isn't a record of that. As for the CEL light, it does light up as i turn the key on, so the bulb works. A faulty ECU wasn't on my list of probable causes, should i consider that a possibility?

 

Check the O2 sensor, MAF, and cat converter. If all checks out, make sure that car is HOT when going on the rollers. Drive it balls our on the freeway for 5-10 minutes prior to pulling into the station, and have it go on the rollers immediately. Hot vs Warm/Cold cat converter make huge difference in testing numbers.

 

I would start by having an exhaust shop test/inspect the cat.

 

Thanks guys! I'll have the cat tested today and let you know how that goes.

 

It definitely needs the EGR ports of the intake cleaned out. They are gunked up pretty bad. Not sure how much this contributes to your emission numbers. Anyway, it needs to be done regardless. Search for the diy with lots of pics and detail on how to clean the intake system. Very easy job technically....but tedious to clean all the passages. You gotta clean the EGR valve and its port on the block too.

Also check out cat and O2 sensors.


Here is Scotty Kilmer with good tips:

 

seafoam will raise your numbers for a few tanks!
but it does clean out crud
how did you use it--amount?

low mpg and high numbers- I agree with kris- muffler shop for cat inspection
possible bad O2 sensor but no code yet~

random or multi misfire codes often 1 bad coil
WHAT PLUGS exactly did you use?
anything but the $8 each ngk iridiums is part of the problem,,no bosch no 2 buck specials--this is a high energy ignition and melts the wrong plugs

ECU failure is rare to extremely rare,,look at obvious probs instead
we have egr system clogging prob- need to remove intake manifold and clean fully every 75kmiles
not found in any maitenance schedule and most techs wont think its possible to be that bad--but it is! see diy and many pics on here
Machine shop can soak clean and ream all the passages clear for a small charge
or you use 3 cans carb cleaner and a wire coat hanger for an hour diy

 

once you get the mixture/mpg issue resolved- change oil and filter
hydrocarbons get trapped in the oil,,fresh oil will lower it!

must reset ECU each time you change something during diagnosis- let car run a self test on all parts
remove the CLOCK fuse on passenger end of dash for a minute- forces full reset instantly

hows the air filter?
and the throttle body air plate- dirty? use carb cleaner for that part

 

I used the sea foam after the first failed test. The plugs were ngk platinum i believe and they were also changed after the first fail.

The ECU showed "not ready" on many of the checks which is why the testing facility did the manual test. However, the first test was 2 weeks after purchase and a 1,000 mile road trip later(which is when i noticed the poor gas mileage. 19mpg highway) I would think that much driving would have been enough for the ECU to go through it's cycle.

The shop I stopped at today blew off the questions i had about the cat being the culprit and wanted to run a full diagnosis at a ridiculous price. I will have to find time to take it to a more helpful shop.

I did remove the EGR valve after the first fail and there was barely a light dusting of carbon on the visible areas(I know this doesn't rule out an internal blockage, I'm just trying to be as descriptive as possible)

 

A couple of things you could try......clean the EGR passageways under the intake, perform the "Seafoam" vac cleaning, run some FI cleaner through the gas, buy the highest octane fuel available, and then run the car on the freeway in a spirited fashion to help clear the cat con......clear the codes and see if it passes, if not replace the front O2 sensor.

 

It seems clear to me the problem is either cat or misfire. Maybe both.

Have cat tested first. Could solve the problem.

If cat is fine, check for which cylinder is misfiring. Disconnect each coilpack and listen for a change in the idle.

 

go to a MUFFLER shop not a general repair place and the 1 hour diagnostic charge

muffler shops have to document for the govt why a cat is being replaced
they test flow rate-pressure,, and the easy test is a non contact infrared thermometer pointed at cat
does it smell like rotten eggs when you drive? = cat

egr port under valve not the problem area,,the passage that connects to gets crudded up

ecu only needs an hour of mixed freeway and city drive to get enough info for testing
if you had just reset it or pulled the battery neg cable,,it says not enough info
until its been thru various cyles/conditions

how did you use the seafoam--in fuel - at what ratio? or thru master vac port?