cxxm

This is just information/comparison based on my experience.

I have a 1984 Trans Am 305 L69 5spd. I did the following to make my car pass emissions.

State Requirements for Emissions:
- HC PPM IDLE: 220
- HC PPM 2500 RPM: 220
- CO% IDLE: 1.2
- CO% 2500 RPM: 1.2

1st Emission Test Results:
- HC PPM IDLE: 1547 Fail
- HC PPM 2500 RPM: 249 Fail
- CO% IDLE: 6.1 Fail
- CO% 2500 RPM: 3.2 Fail

Notes: Engine Condition for 1st Test:
- Original engine never rebuilt. (Replaced nylon timing gear.)
- Replaced 14014416 305 head with rebuilt 14022601 305 Heads
- Edelbrock 1406 600 cfm carburetor
- K&N filter E1650 14’’x 3’’ Air filter
- 2701 Edelbrock intake
- Emission Equipment:
o EGR Valve: No
o Smog Pump: No
o Air Diverter Valve: No
o Air Injection Pipes to Exhaust Manifold: No
o Air Injection Pipe to Catalytic Converter: No
o Catalytic Converter: Yes
o PCV: Yes
o Air Snorkel: No (Not required for test)
o Charcoal Canister: No

2nd Emission Test Results:
- HC PPM IDLE: 549 Fail
- HC PPM 2500 RPM: 203 Pass
- CO% IDLE: 1.81 Fail
- CO% 2500 RPM: 1.89 Fail

Notes: The only thing different from the first test was that the 600 cfm carburetor had its fuel air mixture adjusted as lean as it would stay running.

3rd Emission Test Results:
- HC PPM IDLE: 1337 Fail
- HC PPM 2500 RPM: 70 Pass
- CO% IDLE: 5.48 Fail
- CO% 2500 RPM: 2.2 Fail

Note: The only thing different from the second test was that the 600 cfm carburetor was replaced with a 500 cfm Edelbrock carburetor (1403). The car idles smoother with the 500 cfm, does not smell of gas and gas mileage has improved by 1-2 mpg. 600 cfm carb was choking the engine with to much gas.

4th Emission Test Results:
- HC PPM IDLE: 649 Fail
- HC PPM 2500 RPM: 247 Fail
- CO% IDLE: 3.94 Fail
- CO% 2500 RPM: 4.58 Fail

Notes: The following are the differences with the 3rd Test:
- 1403 Carburetor air fuel mixture adjusted as lean as it would stay running.
- Stock Aluminum Intake Reinstalled. (Not much difference from Edelbrock Intake. In fact I think the stock intake does a little better job. The car starts a little easier. No real change in performance)
- Emission Equipment:
o EGR Valve: Yes/ Operational running off vacuum (Autozone EGR 141) Required use of Summit 52115 EGR adapter on stock intake, because EGR valve runs into Edelbrock carburetor. Used a vacuum T to tie the EGR hose into the Timed vacuum port on the Edlebrock carburetor that is also being used by the distributor and the charcoal canister. I noticed no change in engine performance after installing EGR valve.
o Charcoal Canister: Yes/Operational (Used a vacuum T to tie the tank hose on canister into PCV port on Edelbrock carburetor. Used another T to tie the carb hose on the canister to the Timed vacuum port on the Edelbrock carburetor that is also being used by the distributor and EGR valve. Seems to work. No sound when I take off the gas cap. It was tested and passed emission inspection.
o Smog pump: Yes/Non-operational. (Belt not hooked up)
o Air Diverter Valve: Yes/Non-operational (Requires use of computer with stock carburetor)
o Air Injection Pipes to Exhaust Manifold: Yes/ Operational, but not using.
o Air Injection Pipe to Catalytic Converter: Yes/ Operational, but not using.
o Catalytic Converter: Yes. Replaced the stock 26-year-old burned out converter with a new universal high flow Magna Flow Catalytic Converter (94016). The old converter was completely hollow and the exhaust was just blowing through. No Air from the smog pump was being pumped into the converter during this test. Also, car was quieter and no loss in performance with new converter.
o PCV: Yes
o Air Snorkel: No (does not require for test). Using K&N air filter.

5th Emission Test Results:
- HC PPM IDLE: 97 pass
- HC PPM 2500 RPM: 80 pass
- CO% IDLE: 0.07 pass
- CO% 2500 RPM: 0.29 pass

Notes: Carburetor was not adjusted down, but left at normal/good operation level (Air/Fuel mixture screw turned down till idle drops, then quarter turn back the other way). Smog pump belt installed and air hose ran from smog pump straight to catalytic converter air injection pipe (The air injection pipe near the catalytic converter was rusted and broken. I replaced a one foot section from the catalytic converter to the air injection pipe with Silicone Heater Hose (Flex Fab 5526-050; 1/2''; $10 per foot; blue outside, red inside.) It has been working fine so far.) Air being pumped to the catalytic converter 100% of time.

6th Emission Test Results (Retest):
- HC PPM IDLE: 102 pass
- HC PPM 2500 RPM: 152 pass
- CO% IDLE: 0.05 pass
- CO% 2500 RPM: 0.68 pass

Notes: No changes made from 5th test.

7th Emission Test Results (Final):
- HC PPM IDLE: 142 pass
- HC PPM 2500 RPM: 96 pass
- CO% IDLE: 0.07 pass
- CO% 2500 RPM: 0.11 pass

Notes: No changes made from 6th Test. Fluctuations might because of a tired camshaft.

Special Note: Car had new oil in it and spark plugs. It was driven for 20 minutes before going to the testing station. Once at the testing station it was shut off until the technician was ready. It was run for one minute to clear out the system, before the technician inserted the probes. Allowing the car to idle before the technician is ready seems to create higher emission readings at idle. It seems better to leave the engine off until a minute before the probes are ready to go in for the test.


See chart for all results


Overall a new Catalytic Converter with air being pumped from the smog pump seems to be the key to passing emissions.

Problems: The biggest problem seems to be getting the air diverter valve to work without the use of the computer and stock carburetor.

The air diverter valve controls the air from the smog pump. The smog pump sends air to the diverter valve. The diverter sends air through hose to the air injection pipes that either goes to the exhaust manifold or the catalytic converter. Otherwise, air is diverted to a small muffler next to the pump that vents the air to the atmosphere.

Air injection to exhaust manifold: This only occurs during open loop mode when the engine is first started from cold. Its purpose is to heat up the catalytic converter quicker. This could occur anywhere from 6 to 120 seconds. I have heard, but not confirmed that running air 100% of the time to the exhaust manifolds can create explosions in the exhaust that could cause severe damage. It seems to make sense, because the exhaust system pulses and adding oxygen to unburned gas can make things very hot fast.

Air injection to catalytic convert: This only occurs during closed loop mode. It will not occur if the engine is running too rich, during deceleration, or high rpm operation when air pressure is greater than the setting for the internal relief valve. I have heard that running air 100% to the converter will shorten its life, because it will run hotter than normal instead of just receiving pulses of air. It also seems that the engine runs rougher than normal. Kind of like blowing on a campfire to make it hotter. Not running air to the converter will cause it not to work and possibly plug up over time. However, air must be pumped to the converter 100% of the time in order to pass the emission test.

I have read about pulse air systems (aspirator, check, gulp or reed valves) that open and close based on the pulsing of the engine exhaust. At any rate, I still have not been able to find out how much airflow a catalytic converter needs to operate effectively.

Lastly, Autozone is a good place to find cheap emission parts (air injection pipes, valves, etc. Good luck…

cxxm

Just an update,

Two years later and it is emission-testing time. The catalytic converter (Magna Flow 94016), I purchased two years ago was completely burned out. I was getting HC readings above 500 ppm once again.

During these past two years, I fixed a warped/leaky intake manifold and the stock camshaft has an intake lobe that was completely rounded on cylinder number seven.

The Magna Flow Converter 94016 was some what plugged up, but you could still see through it. The only guess is the combination of a bad camshaft, rich Edelbrock carburetor and no air from the smog pump burned it out. I tried SeaFoam in the fuel and pumped air straight from smog pump to the converter, but no luck.

I did some fixes and here are the new numbers as of 8/7/12:

HC PPM IDLE: 14 (220 Limit)
CO% IDLE: 0.01 (1.2 Limit)

2500 RPM test not required due to passing the idle test.

Here is how I passed:

1) New Catalytic Converter: Magna Flow 93516 (Suppose to be a step up from 94016)

2) Replaced Edelbrock 1403 500 CFM carburetor with the factory E4ME Qjet (found one in the salvage yard for $25 from a 1987 firebird).

3) Replaced stock cam shaft with Edelbrock 2102 camshaft (50 state legal and has EO number).

4) Other than the camshaft and the converter everything on the car has been returned to factory settings (carb, air injection, etc)

Air injection to exhaust manifold: Now controlled by computer. I hooked up an LED light to the solenoid that controls the airflow. When the weather was cold the light was coming on showing airflow during open loop, but once the weather got into the 90’s I have not seen it since. I’ll expect it to come back on when the weather turns cold.

Air injection to catalytic convert: Now controlled by computer. I hooked up an LED light to the solenoid that controls the airflow and a switch that allows me to ground the solenoid to bypass the computer if necessary. The majority of the time the LED only comes on during open loop not during closed loop. It did come on during closed loop when I had the intake manifold leak causing huge drop in vacuum. During the emission test I used the grounding switch to bypass the computer and send air to the converter during the test. After passing the test I turned the grounding switch off and LED remained on for a while. Not sure why.

I am going to retest the car in a few months to see if there are any changes to emissions and to make sure the converter is still working.

cxxm

I was curious, so I put the Edelbrock 1403 500 CFM carb back on to see how it would do on the emission test.

HC PPM Idle: 39 (220 Limit)
CO% Idle: .10 (1.2 Limit)

As you can see the numbers are very similar between the two carbs.

Edelbrock sells a 1400 600 cfm emissions legal carb and the only difference I could find between the 1400 and 1403 is a canister vapor vent port. The E4ME factory carb also has the canister vapor vent port. The 1403 does not have this port.

Also, I have to manually turn on the air injection solenoid each time I start the car. If the car is cold I leave it on for about three minutes. If it is warm I leave it on for a minute. That is all the factory computer has ever done.

cxxm

Another update:

Retested emissions with the Edelbrock carb a month or so later. Failed the test. High emission numbers like the years before. It seemed that the new converter was burned out once again. I tried messing with the mixture and pumping more air, but nothing worked to bring the numbers down.

By the way the Edelbrock was getting 20-21 mpg on highway and 12-13 mpg in the city. It also had a dead spot taking off from idle. It was ok, but never felt quite right.

I believe factory numbers were 18 mpg highway and 13 mpg city.

Found another E4ME Quadrajet in the salvage yard for $25. It came off a 1985 Chevy Caprice with a 305. Holy Cow what a difference!! It is true what they say about Quadrajets. When they run good they really run good. This Quadrajet kicks butt!! More power and excellent throttle response. I can hardly believe it. 19-20 mpg highway and 13-14 mpg city. Also, you can tell a good E4ME by the clicking noise it makes when you turn the key on with out starting the car. The first E4ME, I had made no clicking noise. The clicking noise is the mixture control solenoid inside the carb.

Retested emissions with the Quadrajet. All the numbers were back down like I describe up above. HC were 15 ppm. Seems the cat was not dead after all. The computer was not even pumping any air to the cat. In fact the air injection has only been coming on for about a minute during start up and that is it.

My theory is that over time the Edelbrock must just pump the cat full of unused fuel causing it to fail.

Hope this helps someone....

cxxm

Update. Here are my mpgs for the roughly 920 mile trip from Idaho to California.

Boise to Twin Falls: 17.7 mpg at 75 mph (had some hills, head winds and turned ac on and off a lot.)
Twin Fall to Ely, Nevada: 20.3 mpg at 70 mph
Ely, Nevada to Las Vegas: 20.6 mpg at 70 mph
Las Vegas to Los Angeles: 21.2 mpg 70 mph (Seems like there were a lot of down hills.)

I was running cruise control for the entire trip.

I am running all stock, including the E4ME carb.

More updates to follow……..

Ozz1967

iTrader: (4)

To one of your previous posts, a clicking Carb means the MCS is functioning properly.

cxxm

I was completely wrong. The emission devices follow the factory and service manuals to the letter. I found this out after fixing a vacuum leak. The car runs completely different now.

Here is the link to what happened:

https://www.thirdgen.org/forums/carb...code-41-a.html

cxxm

Update:

It is time for another smog test. I have had trouble with the converters in the past, but the one I got now has been on for two years. Completely stock set up.

I usually get tested in Idaho, but have been down in Southern California and decided to try my luck here. I would say it is the super bowl of emission tests.

When the technician pulled it into the bay, he gave the carb to much fuel and it was kicking out some nice black smoke. I could tell by his face that he had a lot of doubt. Anyway, he went all through the car and checked for everything (timing, visual checks, the works…) I mean he checked everything.

He did have a hard time getting his fuel cap to fit for the tank pressure test, but he got it figured out. I have trouble with my gas cap sometimes. I have bought a couple of different caps and they all seem to be a little off on the fit. When it is cold outside they go on ok, but when it gets hot they seem to warp a little. It’s almost like they aren’t quite the right size. His cap seemed to have the same problem. I think he might have thought I modified the filler neck, but it is stock. My cap does seal even with the difficulty.

I’ll admit that I was pretty nervous, but here are the results.




It passed with no problem! After years of work, it passed the hardest test...

The place I went to was

GKM Garage, Inc
7582 Warner Ave Unit F & G, Huntington, Ca 92647
(714) 841-8284.

I felt like they were honest and fair, but do not go in there thinking they’ll cut you a free pass. They check for everything.