Smog check FAILED!

ac011

ac011

Experienced Member
Joined
4 September 2002
Messages
515
Location
San Francisco, CA
My 91 Failed California Smog check today.

HC (PPM)...... NO (PPM)

MAX .MEAS.... MAX ..MEAS
114...215.......785 ...1366....15 mph
88 ....162........724 ..1098....25 mph

91 with 110000 miles
Comptech exhaust, header
Downforce AIS


Need help on pass smog.


Thanks!
 
Last edited:
add a can of seafoam to the tank, thats what alot of the 1st gen TL guys did to pass, also it improves preformance as it clears up clogged injectors and also cleans up carbon buildup
 
In my hot rodding days, I was able to pass smog checks by adding octane boost to the gas, essentially methanol, running high octane race gas, and making sure the engine and the cats were hot. I would not let the engine cool down prior to having the smog check. If there was a wait, I would ask when to be there and drive around until the test. Octane boost can be bought at any automotive store. It is not an injector cleaner but genearally methanol which burns cleaner than regular petrol.

Obviously, if your plugs are fouling (Need replacing) or your ignition timing has you running rich, you can fail the test. I am not a mechanic but the above might be an inexpensive fix to get you to pass. Good luck.:cool:
 
Those numbers are high! If the engine is running ok and you are getting no CEL for the O2 sensors, I would suspect the cats as the culprit. Change those out with a universal set, dump a can of denatured alcohol in the gas tank and get the cats hot right before the test. Should be good to go. Good luck!
 
My plugs are good (replaced 15000 miles ago). I run my car very hard before I went to the test station, but I need to wait 20min before they took the test. :mad:


The car runs good and no CEL. I thought Comptech come with new O2 sensors with their header?
 
It appears that your cats cooled down. All your numbers are high. When mine fails it's usually one of the four that is high and interestingly it's never the same from one test to the next.

The cats drop from operating temp. within about 5 minutes, even if you run at idle or rev the engine while your waiting. I think headers let the temp. drop faster since you don't have the mass of the stock headers holding heat.
I assume you get a free retest.
A fresh oil change will help.
I don't know about the suggestions above, I haven't tried fuel additives.
Try to arrange running the car right into the test stall after a drive.

If it fails after that, time to check further. Try the cheap things first, oem cats are very expensive, aftermarket is less, but not the first thing I'd replace.
Sulley
 
If you want to try cheap things first, give this bad boy a try www.rxp.com. $5.00 at Autozone.

Worked for me when my Civic kept throwing CEL for a failing Cat.
That is, it threw a CEL after it had enough time to register "normal" emission readings via OBDII, just enough for me to make it through the Smog check by the skin of my teeth... I replaced the cat anyway.. but it was a cruiser.
 
ac011 said:
My 91 Failed California Smog check today.

HC (PPM)...... NO (PPM)

MAX .MEAS.... MAX ..MEAS
114...215.......785 ...1366....15 mph
88 ....162........724 ..1098....25 mph

91 with 110000 miles
Comptech exhaust, header
Downforce AIS


Need help on pass smog.


Thanks!
Click to expand...

Installed new O2 sensors and it passed! But the number still high. :mad:

HC (PPM)...... NO (PPM)

MAX .MEAS.... MAX ..MEAS
114...93.......785 ...771....15 mph
88 ....72.......724 ...598....25 mph
 
ac011 said:
Installed new O2 sensors and it passed! But the number still high. :mad:

HC (PPM)...... NO (PPM)

MAX .MEAS.... MAX ..MEAS
114...93.......785 ...771....15 mph
88 ....72.......724 ...598....25 mph
Click to expand...

yea those # still pretty high theres probly alot of carbon build on on the pistons. i would suggest you do the sea foam it works wonders and i have a special injection system to use with the seafoam which saves alot of time and trouble, sounds like you are in the Sacramento area if you need help to clean up those internal pistons and TB etc give me a call 707-628-7886 i used seaform right before the smog and passed the test with flying color 2 days later.
jeff
 
ac011 said:
Installed new O2 sensors and it passed! But the number still high. :mad:

HC (PPM)...... NO (PPM)

MAX .MEAS.... MAX ..MEAS
114...93.......785 ...771....15 mph
88 ....72.......724 ...598....25 mph
Click to expand...

Hey Anthony does that mean it passed or do you still have to retest? If it passed give me a call I have another local nsxer who would like to borrow the cats. If not, its cool bro let me know whenever you do. Also I can get your car to pass smog I have a few friends in the business with thier own shops if you need. You will get my price so its gonna be a deal.
 
yaynsx said:
Hey Anthony does that mean it passed or do you still have to retest? If it passed give me a call I have another local nsxer who would like to borrow the cats. If not, its cool bro let me know whenever you do. Also I can get your car to pass smog I have a few friends in the business with thier own shops if you need. You will get my price so its gonna be a deal.
Click to expand...

yes, it passed without using ur cats. I will call u next Monday to return the cats. Thank you very much!
 
AutosportsCO said:
What I heard from my partners at work is that if you drive the car for 80+ miles with the A/C on and then do the smog test after your drive, it should pass.
Click to expand...

why the A/C on? it does not change emissions.

here is what we usually do toi get customer and my personal cars to pass smog.

91 octane
1 can of octane booster ( outlaw )
make sure the car has a good tune up. plugs, air filter, etc.
retard timing 5 degrees
take the car for a drive around town keeping rpm high.
when i get to the smog station, if i can get it right on the rollers its best.
if you cant, leave the car running while your waiting.
ask the smog tech to keep the car in 4000 rpm for 30 seconds before running the smog check.

personally i have gotten cars with 2 cats to pass on just 1 secondray cat by using this method ( did know the primary cat was gutted at the time :tongue: ) also had great sucess getting high numbers to come down and pass.

good luck.

Rob
 
RON98 said:
why the A/C on? it does not change emissions.

here is what we usually do toi get customer and my personal cars to pass smog.

91 octane
1 can of octane booster ( outlaw )
make sure the car has a good tune up. plugs, air filter, etc.
retard timing 5 degrees
take the car for a drive around town keeping rpm high.
when i get to the smog station, if i can get it right on the rollers its best.
if you cant, leave the car running while your waiting.
ask the smog tech to keep the car in 4000 rpm for 30 seconds before running the smog check.

personally i have gotten cars with 2 cats to pass on just 1 secondray cat by using this method ( did know the primary cat was gutted at the time :tongue: ) also had great sucess getting high numbers to come down and pass.

good luck.

Rob
Click to expand...

How do you retard the timing on an nsx?
 

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