So I failed emissions. My CO was at 109.98 the limit is 030.00 So this means that I'm running rich or just not burning enough fuel. Now I did notice that the previous owner disconnected the smog pump also noticed that the pulley is seizes. Would replacing the pump help with the CO? I was also thinking of adjusting the carb but I would like to make sure that I will be turning the rite screws. Do I turn the 2 screws to the front of the carb one under the fuel filter and the one to the right of that? Do I back out the screws to lean out or do I seat the screws to lean out? The carb is a stock Rochester Quadrajet
on my 84 Camaro Z28.

 

your computer controls the carb rich/lean settings via the O2 sensor. i think the smog pump is ur problem. it pumps air into the exhaust manifold to burn off and unburned fuel after combustion. it also pumps air into ur catalytic converter to make it work better. do that, and make sure to run the car a while and get the cat nice and hot before the test. it'll have the most efficient results that way.
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also, how old is ur cat? if it's bad, it'll cause ur CO levels to raise (cat converts CO to CO2).

 

how is your gas mileage? if its low you may have a weak O2 sensor. Replace O2 first, replace smog pump if all the plumbing is in good shape (airtubes to each exhaust port, diverter valve and hoses from pump, tubes to cat.), if the air system plumbing isnt intact the air pump wont do much at all.

Take the flange loose from your intermediate pipe at the back of the cat and shine a light up in there...if its a big empty hole, well a shiny new hi flow cat may be in your future.

it is possible for a vehicle in good tune to pass a sniffer without air pump or cat (i've done it, back when FL had sniffer test).

 

My gas mileage is horrible. I did hit the o2 sensor while i was changing the plugs could i have messed it up? my mileage was good when i bought the car.


I have the emissions results in front of me this is what it says.

HC grams per mile 03.37 limit 02.00 Fail

CO grams per mile 109.98 limit 030.00 Fail

NOx grams per mile 00.45 limit 03.00 Pass

 

yes you are running very rich, if mileage has dropped since you got the car then go through the usual tune up routine and maintenance checks....check/replace: plugs, cap, rotor, O2, Coolant Temp Sensor (both sensors can be weak or failing and causing the computer to enrichen the fuel mixture). Check for vacuum leaks. Does the car bog down? How is your idle?

O2, CTS (this is the one in the water neck, not the head), and smog pump are less than $20 ea. If your mileage has tanked and nothing has been done to the carb, then O2 and CTS are likely culprits.

Are you throwing any codes?

 

I need to replace the engine light bulb its been removed. ERRR.

Do you have a pic of the CTS on the water neck?

 

lol i was in awe when I got my 87 and the darn light worked. 1st one ive ever seen that worked.

your water neck should have 2 bungs in it. should be 2 brass looking units screwed in there. 1 should have 2 vacuum fittings, with vacuum lines attached, this is your vacuum actuator switch for the EFE valve. the other should have a 2 wire weatherpak connector, this is the CTS.

 

So I need to replace the waterpack connector?

 

if you hit the O2 sensor and from that point on it was sucking too much gas, then try replacing that first. autozone will scan the car for free, so you could try that before anything...they may be able to tell you if a sensor even works anymore. probably the fastest way to advance your problem solving.

 

No you need to replace the thing its plugged into. Its a brass (usually) sensor screwed into the water neck.

The coolant temp sensor tells the ECM what the coolant temp is. This is how the computer determines to turn the fan on (if you have an electric fan, 84 LG4 might be mech.) It is also how the computer determines the engine temp and will enrichen the fuel mixture if it sees the engine is too cold.

 

The CTS tells the ECM what the coolant temperature is, but it doesn't have anything to do with the coolant fan on carb'd cars. That's the job of the switch in the passenger side head.

But, an '84 LG4 would have a mechanical fan, anyway.

Before you go changing parts, get that SES bulb replaced so you know if any trouble codes are being set. After you check that, fix any that are indicated and go from there. Replacing parts at random because you haven't replaced a $0.50 bulb doesn't make any sense.

 

I really hate to disagree with you five7 (mostly cause you know waaay more than I do ) but early electric fan cars run off CTS and do not have a separate fan switch. My 87 LG4 does not. IIRC it was actually later year TBI and TPI cars that went to the separate fan switch, but I might be wrong.

+1 on that! I didn't catch that the bulb had been removed. Definately check for codes.

 

My '86 has the switch in the head (which actually energizes a relay) with no connection to the ECM. The relay is also energized when the air conditioning is turned on.

 

hmmm I wonder what reasoning was for the different setup. Both my 85 and my 87 have ECM controlled single electric fan setups. 85 is an LB9 and 87 is an LG4.

Yeah fan relay should always be energized by turning A/C on.

But we digress....back to the topic at hand...