Smog help please!

[Mark Galarneau]

I just love good old California. I live in the Palo Alto area of CA. Got a '91 with RM headers and exhaust -- other than that, the engine is bone stock. I'm the original owner and the car has extremely low miles and had a major tune-up, timing belt, etc. done just one year ago. Need to smog it at a "Test Center Only" station -- and it failed (the Test Center I went to is on Woodside Road in Redwood City). So I talked to Foreign Affair in Milpitas about taking off the headers/exhaust, smogging it, then replacing the aftermarket stuff, but they said if it wasn't 50 state legal, they couldn't put it back on. I called RM and was told it's not 50-state legal, but he said many, many people have their parts on cars in CA and no one has called with smog problems. So...

Does anyone have RM exhaust/headers locally and has had it pass smog? The RM guy said to check around because there must be a Test Center that will pass it (without taking it off).

Ugh. Nothing is simple. Thanks for any help/advice!

Mark

 

[Dinan M3]

Did you fail the smog check due to visual inspection (i.e., the non-CARB-certified aftermarket header) or because of emissions results?

 

[D'Ecosse]

I would not expect your test to fail because of those components - as DinanM3 asks, if it failed for visual that's one thing - if for emissions, you may (likely) have other issues.
Note: even though I had a "test-only" requirement (off-topic: the NSX seems to get an inordinate ammount of test-only mandates - not sure why that should be!) the tester did not even look at my after-market exhaust let alone headers - they were Comptech, therefor CARB certified anyway, but you would not expect the test station to be so intimate as to not even ask about them?
You should post up your results, preferably in the tech section, so a more likely analysis can be determined regarding what may have caused the failure.

 

[Racer NSX]

In the past, I and several other NSX owners have had trouble getting our cars to pass the smog test. I last time I smogged the car, it failed on the first try by quite a bit. I tech had me drive the car at high RPM for 30 minutes and come right back to get it tested again. I left the car running as we setup the car for the test and it passed without a hitch. The key item I found for the NSX is to get the cats really hot so they work well.

Now if it failed the visual test, that's another story.

It seems that all early 90 NSXs (<95) are all getting sent to :smog only" test stations. I think that if your car is greater than 10 years old in Cali., it is automatically issues a "smog only" test.

Good luck

 

[Litespeeds]

Please post the numbers for HC, NO2 and CO.

I had problems also and have the Comptech headers and exhaust. My problem was with my EGR valve not opening up enough. You also need to drive your car for at least 15 minutes at higher rpms to get the cats really hot and then test it right away. Even if you just idle your car for 5 minutes before the testing, it cools down and might effect the HC readings.

When I tested mine, it would either pass HC and fail NO2 or the other way around depending upon which gear I was in when they ran the test. We narrowed it down to the EGR not opening up due to a vacuum problem or something like that. In any case, that small part was replaced and I passed. Hope I don't have to go to a Test Only station next year. Good luck.

 

[Mark Galarneau]

Thanks everyone. I didn't fail the visual inspection, I failed the emissions test. This is the only part I failed however: NO (PPM) -- at 25mph the Max. is 724, mine was 879. All the other results passed (HC, CO).

So...

I had not driven the car much at all, maybe 5 minutes at low speed before having the test. I have read a lot here about getting the cats really hot. Do you think it's worth trying that and getting it retested? The guy at the test center felt so bad for me he's giving me another test for free. He couldn't believe I didn't pass.

 

[mickeylex]

I had not driven the car much at all, maybe 5 minutes at low speed before having the test. I have read a lot here about getting the cats really hot. Do you think it's worth trying that and getting it retested?

Yes, get the cats really hot and you should pass with flying colors. Don't spend the money to remove/install the headers since the test center didn't even notice them. I did my SMOG earlier this year. I drove the car in 3rd and 4th gear on the freeway for about 15-30 minutes and went straight to the test center. The readings never got anywhere near the limits. Heat up the cats real good and test it. Unless you have some other emissions-related problem, you should be good to go.

 

[Litespeeds]

Thanks everyone. I didn't fail the visual inspection, I failed the emissions test. This is the only part I failed however: NO (PPM) -- at 25mph the Max. is 724, mine was 879. All the other results passed (HC, CO).

So...

I had not driven the car much at all, maybe 5 minutes at low speed before having the test. I have read a lot here about getting the cats really hot. Do you think it's worth trying that and getting it retested? The guy at the test center felt so bad for me he's giving me another test for free. He couldn't believe I didn't pass.

The other big issue that I forgot to mention is the TCS has to be off in order to test your car. If the tester did not push that TCS button off, then that is another major issue to why it failed.

 

[Sulley]

Brought my 93 into California in 02. I believe I have the RM headers and exhaust. I barely passed when I licensed it the first time.

No one looked for a CARB exemption on the headers(I have to show most smog techs were the engine is), but I was pretty sure they were not approved. The O2 sensors are only in one downtube on each bank of headers, not down at the collector. I think this leads to some of the test problems, sensing two cylinders instead of all six. I was told(for what it's worth) by a dealer that they had problems smogging NSX's with other headers and when people switched to Comptech headers that they passed. Altho as mentioned above they don't always pass either.

When I was sent to Test only in 04. It failed. High NO at both speeds. EGR checked out according to the manual. Lots of trouble shooting. Changed plugs,O2 sensors, and engine oil. Eventually replaced cats. It took six smog checks and the numbers were all over the place. NO really low and fail on HC. Then the opposite. Failed HC and NO. No consistent numbers. Finally passed but very close.

The problem with getting the cats hot is that the techs are so darn slow that everything cools down while they set up. I used an oven thermometer to check the inflow and outflow temps on the exhaust pipes for the cats. They should be around 50 degrees hotter on the outlet pipe than the inlet. You will also find that the overall temps drop quickly after you stop and let it idle. Idle is better than nothing but the cats drop below operating temp pretty fast.

I also finally used a different test center. Most around here have a free retest.

Next year will probably be an adventure again. I may get some new headers before then, if someone ever looks it will fail on the visual.

I can only suggest trying a different center and setting it up so you can drive right up and get them to do a quick setup before things cool off.

Sulley
Merced,CA

 

[spartan2-3]

Mark,

I have Comptech headers and JGTC exhaust and pass smog with flying colors. As Nalesh mentioned, heat up the cats :smile: .

Speaking of smog, I'll need mines done within a week.

good to see you back on prime, I still want a ride in your TR

-Romeo

 

[Mark Galarneau]

Romeo,

TR is waiting for you! What was your friend's name, the one who had the RM exhaust (not sure if he had headers) -- has he had any problems smogging it?

Question for everyone -- so is it the headers more than the exhaust that screw up the smog? If so, I'll keep the exhaust and lose the headers. Too much trouble.

Thanks again for all the replies.

 

[spartan2-3]

Romeo,

TR is waiting for you! What was your friend's name, the one who had the RM exhaust (not sure if he had headers) -- has he had any problems smogging it?

Question for everyone -- so is it the headers more than the exhaust that screw up the smog? If so, I'll keep the exhaust and lose the headers. Too much trouble.

Thanks again for all the replies.

Mark that was Roger, he has a 98 with RM Exhaust but no headers. Funny but I dont recall anyone that visualized my headers? They just plugged the sensors to the tailpipe and ran it through.

Has it only been 2 years since you had your headers put on?

I may go this weekend for smog testing, my reg expires Sept 8. :redface:

Flashback (taken in front of Mark's mansion) :biggrin: