Ok, Im not an expert at smog systems or diagnosis. But I did want to post my
smog ordeal, what I did, and what the numbers said so you can trouble shoot
your car when it fails smog. I would also encourage anyone to add to this post
your experience here so we can have a good "smog" archieve.
From my past posts "help Im a gross poluter", and "fail smog, EGR question",
here is my data and the things I did after each smog test:
Test #1 : Tune up, new wires, oil, & filters (timing was at 5Deg ATDC static)
15MPH TEST
CO2%:14.4
O2%:0.4
HC(PPM): Max 118 Meas 31
CO%: Max 0.68 Meas 0.01
NO(PPM): Max 999 Meas 2347 FAIL
25MPH TEST
CO2%:14.7
O2%:0.1
HC(PPM): Max 98 Meas 31
CO%: Max 0.87 Meas 0.03
NO(PPM): Max 859 Meas 659
Test #2 : Reset timing to 5 Deg BTDC static
15MPH TEST
CO2%:12.9
O2%:2.4
HC(PPM): Max 118 Meas 28
CO%: Max 0.68 Meas 0.01
NO(PPM): Max 999 Meas 2983 FAIL
25MPH TEST
CO2%:13.1
O2%:2.1
HC(PPM): Max 98 Meas 26
CO%: Max 0.87 Meas 0.06
NO(PPM): Max 859 Meas 648
Test #3 : New Catalitic converter and 02 sensor
15MPH TEST (after new cat/O2 sensor)
CO2%:14.52
O2%:0.42
HC(PPM): Max 118 Meas 37
CO%: Max 0.68 Meas 0.02
NO(PPM): Max 999 Meas 2566 FAIL
25MPH TEST
CO2%:14.7
O2%:0.21
HC(PPM): Max 98 Meas 29
CO%: Max 0.87 Meas 0.02
NO(PPM): Max 859 Meas 92
Test #4 : Removed intake manifold pressure wash EGR passage, remove EGR clean
15MPH TEST (after new cat/O2 sensor)
CO2%:14.9
O2%:0.25
HC(PPM): Max 118 Meas 117 BARELY PASS!!
CO%: Max 0.68 Meas 0.08
NO(PPM): Max 999 Meas 152
25MPH TEST
CO2%:14.9
O2%:0.18
HC(PPM): Max 98 Meas 65
CO%: Max 0.87 Meas 0.02
NO(PPM): Max 859 Meas 42
The EGR passage on the intake manifold was completely blocked, and was very
difficult to clean, because there is one bend that is 180 deg. Very bad design.
It would be a good place to add a clean out (like home plumbing) for the future.
So what did I learn from this?
1) If you fail NO's both at 15 & 25MPH, you probably have a bad cat.
2) I think if the 02 sensor is bad, you would get a code from the car's computer.
but it also should be cycled, and checked.
3) If your NO's are very high at 15MPH's but are passing at 25MPH, you have
some problem with your EGR system. If its a GEN I bet on a blocked up intake
manifold EGR passage.
4) If you remove your intake manifold, change all water lines and especially the
fuel lines behind it, cause its much easer once the intake is out. My fuel line
snapped in my hand as I was removing it!! CHANGE FUEL LINE, did I mention
to change your fuel lines?
5) The Haynes repair manual has an error on the proceedure to set the timing.
DO NOT USE THE HAYNES TECHNIQUE, USE THE FACTORY MANUAL.
6) Our older Gen I's can run as clean as new cars if properly maintained. Please
dont remove your smog stuff, its not that expensive to repair, and the air we breath
is filthy enough as it is. You wont get that much more hp removing it. Lets all
be part of the solution, not the problem.
7)Here's how to test your EGR system. This is not in the factory manual. Thre manual
only tells you how to check the EGR valve, and its thermal sensor.
7.1) disconnect vaumn line from EGR valve
7.2) hook up vacumn pump line to EGR line
7.3) appy greater than 5(I think BAR) to the EGR
7.4) Engine should stall, or run very rough (If so EGR valve ok, and passages are clear)
7.5) hook vacumn guage to the vacumn line that you disconnected from EGR valveThis is the vac line going to the air plenum.
7.6) blip engine speed ( 700-3000-700) rev up fast and release
7.7) obvserve the guage, vacumn will also blip with engine speed
7.8) if the vacumn checks out, no plugged line.
If anyone knows why my HC's are so high at 15MPH, please chime in, Im sure
it will be a thorn in my side in two years, when I have to repeat this ordeal.
