Vehicle history:
1990 Civic Si
B16 (CA BAR legal; passed smog 2 years ago, results attached)
YS1 LSD
DC headers (CARB legal)
AEM intake (CARB legal)
Car is weekend driven (about 4000 miles past 2 years)

I didn't happen to watch the tech this time he ran my car, however, I am able to watch input of car data and stand next to car while being tested. The car was very warmed up before testing (driven an hour, 80+ degree day, ran while waiting 5 min. to test).

My questions are primarily:

Are RPM's a consideration during testing... Is there a min/max range technicians should be within? How are results affected by high/low RPM for each speed test? Can this be improved using a longer geared tranny?

Having a hard time understanding why my HC & CO MAX numbers are lower in 2011 than 2009, while NO are unchanged? Wouldn't they be higher if anything... a result of technician error? Just wondering if the tech could have possibly scanned the wrong BAR code inside door jam? I still would have failed, but curious how I am supposed to compare my results when I don't know the "standard" for my engine, since my engine is technically a 94 Civic del sol si.

So I'm trying to stay away from replacing the CAT. In addition to it being replaced 2 years ago and rarely driven, I find it hard to believe it's bad already. It's not from Honda, but an OEM replacement... not one of those hi-flo or otherwise replacements. The o2 sensor is fairly new also, along with dizzy. I also did a full replacement of vacuum hoses last smog as I thought it was related, however, my NO #'s were still high then to.

The only other things I can think of would be simple tuning practices... plugs, wires, cap, rotor, oil change & maybe running some deposit cleaner in the fuel. Just having a hard time understanding the difficulties of the 15mph test when 25 comes out so much better!

Thanks for any responses.

 

To answer your questions...

Yes they did change the max limits and yes they lowered them last year.

RPM we are suppose to use second gear only unless the rpm is out of range for that gear.

The one difference I see is the O2 reading on the new test is .1 the old one is 0.0
I would say that the cat is slowly going bye bye. Now there are two factors that exist
1. the tech did not warm the cat up any before the new test.
2 the header cool's the exhaust down alot before it gets to the cat thus not heating it up enough.

Now for some questions...

Timing is a little more advanced than last test have you adjusted it since the old test?
Did you replace anything since last test? tune-up header etc...
How long has the car been sitting? if more than 3 months you need to drive it around about 300 miles to clean up everything.

let us know!

 

OK, makes sense if they changed the max limits.

Understand the cat feedback, however, I drove the car street/freeway for about an hour before the test and continued to keep car running for about 5 min. prior to test. I'd rule out the header heat loss unless there are specs that support theory on a consistent basis from stock manifold. If that much loss, how would it be CARB approved (not questioning you, just thinking out loud). All food for though with emissions, I know.

I don't recall specifically changing the timing and didn't notice the 1 degree until after testing.
Nothing has been replaced since last test. Just oil changes.
The car is driven usually every other weekend for several hours... maybe 100-150 miles. Have been driving it more regulary lately, but it's my secondary car.

 

I've had problems passing a bone stock 91 SI because of a DC Header. It allows too much heat out of it and would cause it to fail just like yours. As soon as I switched back to the stock header, it passed.

 

Problem is, I don't have a stock b pipe. I assume wrapping DC would produce same benefits... but pose potential cracking problem since they are ceramic?

 

"Just having a hard time understanding the difficulties of the 15mph test when 25 comes out so much better!"

The increase in RPM's and load on the motor during the 25 mph part is going to cause the exhaust stream tempature to rise, this will cause that CAT to get hotter as well making it work more effecient. Thats mostly why you see the drop in the numbers, theres other factors that play a part too though.

 

The 15mph test is at a lower rpm and the dyno is loaded with 50% of the vehicles weight.

The 25mph is usually at a higher rpm and the dyno is loaded with 25% of the vehicles weight. So half of the load on the dyno.

I explain it as: at the 15mph it is like driving up a 6% grade hill, and at 25mph a 3% grade hill.

When you had the first test done did they do it at the ref station? Reason I ask is because most regular smog tech's don't understand the heat loss from the header and the ref might!

 

Well originally when BAR'd it was at a ref station, as is now. However, the 2009 test results I posted were from the same station as 2011 results.

So it sounds like the agreement is within the heat-loss due to headers, at least at an initial starting point. Anything I should be concerned about if I just wrap the DC's with hi-temp insulation wrap, obviously not covering the CARB plate? Or would finding a stock replacement be better suited?

Thanks.

 

I have to agree as well with the header vs the stock manifold. I just smogged my car a few months ago. I dont have a swap or a header but I did replace my cat a few months prior. It passed with flying colors. In fact, when I compared the numbers from the old cat to the new...I was amazed. What a difference! With the old cat numbers were borderline, now its under average. Good luck and keep us posted.