Damn, so close, yet so far. I took my car in for testing today, finally, and came so close to passing! CO and NO were way low, but my HydroCarbons were just over the maximum. I got 110 ppm at 15 mph and 99 ppm at 25. The maximum was 100/85 ppm. So I just barely failed. What do I need to do to burn off those extra hydrocarbons? I serched, and saw mainly that the ignition system is the problem. My plugs, wires, cap, rotor and coil were all replaced about a year ago, but less that 100 miles of driving. Cat is less than 100 miles. My guess is that I'm running to cold. I put in a 180 degree thermostat, and my fan does not work correctly. It only comes on when I switch it on, via the HVAC controls. The temp of my engine never goes about that first mark on the temp gaguge, which is about 1/4 of the way up. So, either I figure out what's wrong with my fan wires, which I have very little faith in my ability to do, or I do what? Thanks everyone.

PS - O2 sensor was replaced as well.

PPS - Couldn't I just put in a higher temp thermostat, like 195 and then the car would run at roughly that temp, and burn just enough extra HCs to pass?

 

Fix your fan and temp situation. Your target AFR might not even be 14.7:1

-- Joe

 

Well, I'd really love to fix the fan situation. However, I have no idea what to do. I'm totally stumped. I've traced all the wires for the fan, and they all go where they are supposed to be going, according to the wiring diagram. There must be something somewhere I haven't seen, it's just too weird. That aside, what do you mean by "temp situation" ? You think the car is running too cold in general? It would be hotter with the fan working correctly, I know.

 

was the cat up to temp? also i think stock your motor is supposed to be around 205-210 normally. so your low temp could casue the failure. retarding the timing slightly might help as well

 

Definately change that thermostat, but also drive it around for a long time before you take it in, and also, if you go to a hotter plug for the test, that would also help. If you want to be really sneaky, get a glow plug (from a diesel motor) and install it in the tail pipe. That will burn off all excess HC.

 

I'd like some more details on this glow plug idea, feel free to use e-mail or PM if you prefer....

 

I have a 180 tstat in my IROC and I pass Cali emissions. Just drive the car around for a while before you take it in, make sure the engine is full up to temp and the cat is nice and hot. Ask the smog tech to run the engine at about 2000 rpm for a minute or two before he actually starts the automated test cycle. That will heat the cat as well as the engine. Make sure your O2 sensor is healthy. Temp of the engine and cat make a HUGE difference in the smog readings. You might also want to dump a little fuel alcohol in the tank. Are your air filters clean?

 

All my filters are clean, and the engine was warmed up. However, it wasn't that warm, because of the way my cooling is set up. My fan doesn't turn on automatically, thus I had to leave it on the whole time it was being tested, or it probably would have overheated. The fan being on, combined with the 180 degree thermostat probably resulted in the high HC count.

 

It's really a fine balance between getting the CO down without HC's climbing. Basically the HC is unburnt fuel. As others suggested get the motor nice and hot. I would also suggest that you back the ignition timing down between 2-4 degs base. This will increase combustion temps and promote a little more efficient burn.

www.geocities.com/dzperf

 

technically its illegal for a tech to do this if the eninge is already warm in ca.

 

Odd. GM service manuals all say a car can return to open loop, and a cat / o2 cool down just by idling in place.

Recommend that the tech do just that, to get the car back into closed loop. (hold throttle @ 2000 rpm)

-- Joe

 

Well, in Cali, if your county has the chassis dyno smog test, the tech has to be sitting in the car with his foot on the gas to do the two speeds, the smog test computer tells him when to increase the speed up to 25 mph. Since he's sitting in the car and watching the speedo, ask him to keep an eye on the temp guage and show him where the fan switch is. Do the test with the fan off to get the engine as hot as possible. Tell the tech to switch on the fan ONLY if the temp gets near the top of the scale.

My fans turn on automatically, and I think I got through the whole test without them turning on. Ideally you'd like to do the test with the engine up around 220 degrees. The hotter the engine is, the better chance you have of passing the test. You also want that cat as hot as possible. I'm telling ya, this makes all the difference in the world. You will NEVER pass with a cool engine and cat.

You can thank our politicians for making this such a PITA ordeal for us.

 

Hey HiTech5, do you mean to retard the timing to 2-4 degrees advance? Mine is currently 8 degrees advance.

Tremo,
I'll try that, last time he said not to be around the car, but this time I'll explain my cooling situation, and see if he'll let me do as you said.

I put in the 195 degree thermostat yesterday, and that seems to have raised the running temp, oddly enough, about 15 degrees. Let's see how it goes this time.

 

my understanding is they check the timing in California, if more then 2 degrees off in either direction it fails.

 

Hrm. I guess I should check my emissions sticker and see what it's supposed to be, huh? I passed on all counts, except Hydrocarbons, and I was at 8 degrees advanced. I even saw the tech check it.

 

I believe that the factory spec for base timing is 6 degs. advance.
I would try to run 4 degs advance for your base.

 

If you didn't pass because of the hydrocarbons, then you definately need to heat things up. Try a hotter plug. I bet that would make you pass. Especially if you drive it around for a while.