nels415

He drove it to complete the drive cycle.

-nels

FlatSix911

I drove my car in for the bi-annual smog check and was required to go to a STAR shop since the 993 is labeled as a HEP (High Emitter Profile).
I always passed the smog requirements previously, but today I failed one test:

I measured 105 HC ppm at 15 mph - the maximum is 59 HC ppm: FAIL
I measured 35 HC ppm at 25 mph - the maximum is 35 HC ppm: PASS

Any suggestions to reduce the HC (Hydrocarbons) for the retest?

Dan V

Ted,

Sorry to hear about the smog test problem. There are numerous possible causes of increased HC, the simplest being lean mixture, often caused by a vacuum leak. Also, as you probably have seen, many have mentioned that it's a good idea to get the cats good and hot and have the test done before they start to cool down, as the cats have max efficiency to burn off HCs when they're at high temps.

I learned a lot about HCs years ago when getting my MGB smogged. I had gutted the cat and a shop in Sunnyvale still managed to get it to pass.

User 122821

Either the cat was cold or the cat is losing efficiently.

PiB993

After I got my Turbo a little over a year ago the dealer didn't have it pass smog (Isn't it the law they are supposed to before they sell a car?) so I brought it in to my local P-car specialist and to the best of my knowledge from what he told me he just hooked it up to a diagnostic machine to reset the codes and then had it passed. I don't believe there was any requirement for a "star" station at that point. I did have to pay for an hour of labor that was later, along with the actual smog test cost, reimbursed by the dealer.

vanguard

Try the Durametric Diagnostic Tool. Someone lent it to me while I was trying to set my readiness codes. It’s basically this cable that plugs into the OBI/II port and software you have to install into your laptop. It tells you when you pass the different stages versus driving aimlessly hoping and guessing it passed. In the right hands, its a tuning aid as well. I was impressed, worth the investment.

FlatSix911

Thanks for all the suggestions on how to reduce the Hydrocarbons for the retest
Notes: I have the durametric software and all readiness codes are fine.
Complete RMG service 6 months ago and hot catalyst for the test.
After a quick Google search, 2 fixes were found on other forums:

• G2P or Guaranteed to Pass additive
• Add Ethanol or run E85 for the test

Can anyone confirm or deny the effectiveness of these additives?
Thanks!

Aircooled Dave

I agree with Dan, a simple vacuum leak sounds like the culprit to me, especially if you just had the car serviced something could have been knocked loose, etc...Your HC readings are 2X above normal @ 15mph so a simple additive is likely a waste of time.

Another common area that triggers high HC is bad ignition timing and/or spark. A quick check to make sure the plug wires are properly seated on both the plugs and distrubutor cap may be wortwhile also.

FlatSix911

Well, after checking everything under the bonnet, I found nothing out of specification.
So I finally decided to give the Ethanol fuel additive a try ... Success!
The measured 105 HC ppm at 15 mph - dropped to 10 HC ppm: PASS
The measured 35 HC ppm at 25 mph - dropped to 20 HC ppm: PASS

Here are the steps I followed along with before and after Smog Test results:

1. Buy 2 quarts of denatured alcohol (Ethanol) from your local Home Depot.
2. Run your fuel down anywhere from 1/4 tank to almost empty depending on how badly your car passed emissions last time.
3. Add the two quart bottles of denatured alcohol into your fuel tank.
4. Warm up the car and drive it immediately to your emissions test.
5. Make sure the Catalyst is hot and run the smog test or pre-test.
6. Fill up a FULL tank to dilute any denatured alcohol that’s left.

Ash

I had a similar issue - I followed a cocktail mix suggested by Steve Weiner - a can of Jectron and a can of Ventil Sauber - my HC's measured 0 on the retest - crazy I know.

vicmt09

Hello there just wanted to chime in and say that today i took my car to the referee in los angeles, LA tech campus to be exact, i went with having 2 monitors not ready and the guys instantly told me as they scanned my car that california only allows 1 monitor not to be ready, even if it's the catalyst monitor that isn't ready then you will pass, i asked this exact question to the referee, as far as having other monitors on though you will fail ,i cannot verify if they still let certain cars pass because of the compatibility problems with their software though. So after the ref told me to come back with only 1 monitor on i decided to drive with my scan tool connected and it cleared it codes about 40 minutes of driving -_- i didn't want to reschedule and wait so instead i took it to the smog place i had failed at for a retest and it passed 8). I know this forum is only for porsche vehicles but from here i learned about the referee program, i myself don't have a porsche and this is my only post but i am considering getting a boxster next , i just wanted to add updated information on here for the referee program in california. This might be a little irrelevant but i also wanted to add what i did to get my monitors on, it might help someone, i was following the bmw drive cycle, for obvious reasons, the car i have is a z4 roadster, i found out that you don't need a cold start every time you want to get your monitors on, example the evap monitor turned on last week after a few starts and engine temperature was at a moderate level. So this morning after i left the referee station i still had two stubborn monitors on : 1. Catalyst Monitor , and 2. Oxygen Sensor Monitor. All i did was drive on the freeway for about 40 mins, that included being tied down in l.a morning traffic around 8 am ,i went over 3,000 rpm which the bmw cycle claims it will discontinue the current cycle (not true) , went well over 60 mph and did a lot of heavy stop and go traffic which probably helped turning on the monitors there and then , also let the car idle for 4-5 minutes before turning the car off. If you have done highway driving then it's probably not enough to turn your monitors on, you also need this kind of stop and go freeway traffic to fully stop and go, makes the catalytic converter hot therefore turning on those stubborn monitors on, if you can't find such traffic you can also stop on the shoulder then drive for 5 minutes and repeat until your monitors come on. Conclusion :, i've read many people struggling with these monitors and drive countless miles to try to turn them on, i hope this can be a reference to someone stuck in the same situation that i was in for a long week that almost felt like a month, reading forums and and every piece of information i can find, this seems like a very informative forum and look forward to future discussions when i decide to get my boxter 8)

Jay J

So this,E85 or denatured alcy will work?

FlatSix911

That is correct. Just be sure to fill up with a full tank of gas to dilute the mixture after the Smog Test

911CabSteve

I just take my car to my wrench who has the laptop program. In 5-10 min of driving with the alptop plugged in, he can always get all the codes reset and I then take it to the smog station and pass no problem..

FlatSix911

Thanks - we were discussing the solution to high NOX, SOX, and HC levels.