Another 1991 Fails CA emissions... Help! - ZR-1 Net Registry Forums

RKC · 10-31-2009

I have a 1990 that gave me fits getting pass smog. Here are my results from my first failure.

15 mph / 2294 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 51 (limit 110)
CO: 0.01 (limit 0.71)
NO: 868 (limit 772) ***

25 mph / 2450 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 41 (limit 85)
CO: 0.01 (limit 0.59)
NO: 987 (limit 711)

After I passed:

15 mph / 2190 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 109 (limit 110)
CO: 0.10 (limit 0.71)
NO: 611 (limit 772) ***

25 mph / 2440 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 52 (limit 85)
CO: 0.01 (limit 0.59)
NO: 667 (limit 711)

I passed the test after using fuel injector cleaner, changed the oil, replaced the spark plugs, and cleaned the air filter. I used Chevron gas. My engine has 45,000 miles and blows a little oil on startup.

I did have new bullet cats on SW headers. The cats may have helped ,but they didn't help it pass the first time. I also have 4.10 gears in rear.

One major difference I noticed is the RPM's at 15 mph. In your test, you're barely off idle at that low RPM. Nearly 900 fewer than mine. About 350 RPM's less at 25 MPH.

Also, I'm not sure of the reasons, but in passing the NO portion of the test, I very nearly failed the HC portion. I tested on a summer day. The technician had the car running for nearly 20 minutes before and during the test. With the aftermarket radiator it ran very hot at idle. I subsequently swapped it for a stock radiator and dramatically improved the idle temperature. My point being, the engine coolant temperature had to be extremely high during the test.

Also on the first test failure, they failed me on my gas cap. I replaced it with a new one. Don't know if that would cause any actual exhaust emissions change, but on a newer OBD II vehicle of mine it set an error code that I couldn't solve until I finally replaced the gas cap. It immediately cleared the problem and never reset.

10-31-2009	#22
RKC Join Date: Jul 2008 Location: Southern California Posts: 17	Re: Another 1991 Fails CA emissions... Help! I have a 1990 that gave me fits getting pass smog. Here are my results from my first failure. 15 mph / 2294 rpm CO2: 14.7 (no limit) O2: 0.2 (no limit) HC: 51 (limit 110) CO: 0.01 (limit 0.71) NO: 868 (limit 772) * 25 mph / 2450 rpm CO2: 14.7 (no limit) O2: 0.2 (no limit) HC: 41 (limit 85) CO: 0.01 (limit 0.59) NO: 987 (limit 711) After I passed: 15 mph / 2190 rpm CO2: 14.7 (no limit) O2: 0.2 (no limit) HC: 109 (limit 110) CO: 0.10 (limit 0.71) NO: 611 (limit 772) * 25 mph / 2440 rpm CO2: 14.7 (no limit) O2: 0.2 (no limit) HC: 52 (limit 85) CO: 0.01 (limit 0.59) NO: 667 (limit 711) I passed the test after using fuel injector cleaner, changed the oil, replaced the spark plugs, and cleaned the air filter. I used Chevron gas. My engine has 45,000 miles and blows a little oil on startup. I did have new bullet cats on SW headers. The cats may have helped ,but they didn't help it pass the first time. I also have 4.10 gears in rear. One major difference I noticed is the RPM's at 15 mph. In your test, you're barely off idle at that low RPM. Nearly 900 fewer than mine. About 350 RPM's less at 25 MPH. Also, I'm not sure of the reasons, but in passing the NO portion of the test, I very nearly failed the HC portion. I tested on a summer day. The technician had the car running for nearly 20 minutes before and during the test. With the aftermarket radiator it ran very hot at idle. I subsequently swapped it for a stock radiator and dramatically improved the idle temperature. My point being, the engine coolant temperature had to be extremely high during the test. Also on the first test failure, they failed me on my gas cap. I replaced it with a new one. Don't know if that would cause any actual exhaust emissions change, but on a newer OBD II vehicle of mine it set an error code that I couldn't solve until I finally replaced the gas cap. It immediately cleared the problem and never reset.