Okay, I'm soon-to-be an inspector so I have access to the machines. I did a manual reading of the exhaust gases just to see what I was doing to the environment, and it was horrible. HC was 720 and CO was 2.2. (Legal is 220 and 1.2).

So, what can I do to get those numbers down?

The ECM isn't throwing any codes, I have a new air sensor, plenty of oxygen is getting to the engine since I have an open element air filter with a K&N filter. The spark plugs are pretty new (AC Delco's), the oil is changed regularly, the PCV valve is new.. The engine runs fine, spark plugs come out looking brown which indicates to me a normal condition but the 720 HC reading indicates rich.

So...

Things I haven't replaced are the EGR and charcoal canister, but I can't imagine those would help THAT much with the HC's. The cat is pretty old, probably stock.. That could be it, but I'd like to diagnose less expensive things first. The engine doesn't run cold, and it runs pretty smooth. Except at idle, which I'm going to guess is a vacuum leak somewhere that I haven't been able to trace yet. But it seems like a vac. leak would increase O2 going into the engine and thus reduce HC's.

Any ideas?

The vehicle was fully warmed and in closed loop mode, if anybody's wondering.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Bad or plugged cat would cause high readings.
SSC

 

What was the o2 reading?

 

Jeezus christ!! My record it 356 HC and I have a carb!! Is that at idle or high speed? Things that I would check/replace:
O2 Sensor
EGR Valve
Catalytic Convertor
Smog Pump and AIR regulator
Fuel Injectors (actually, entire Throttle Body)



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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."

 

Get a new cat and fill up on dry gas. Keep your coolant temo between 220 and 240 degrees.

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Hybrid Black 5.7L 5 Speed
'95 Competition Yellow Corvette Coupe ZF6

 

I just passed a few weeks ago with a reading of 90HC, so I would suspect that something is wrong with your car Try the Jiffy Lube in Cary off Walnut by Crossroads... it may still pass.

A clogged cat will give you those numbers. Heck, a gutted cat may give you lower numbers then that! How does your smog pump look? It's obvious if it has siezed up, but it should be connected because it flows air to the cat to help keep it from getting clogged. Try hitting it with some carb cleaner (if you can on a TBI... I honestly don't know).

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Well.. It's not due until October, and I'm an inspector, so it WILL pass one way or another.

However, I'd _like_ for my car to be a lot cleaner than it is. I'll probably replace the cat, it's about 12 years old. Or at least, it looks that way.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Those numbers are about what a typical car running properly with no cat might produce.

Put on a new cat.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Before you throw the bucks down on a new cat replace the old O2 sensor. They get flaky sometimes and if the engine reads too lean from the O2 the ECM will run it rich to compnsate. Also, beg borrow or steal scan tool. You can't tell squat about a computer controlled car unless you see things likethe ECM sees them.

It could still be a gutted or burnt cat, but don't just row part at it unless money is no object.


[This message has been edited by Damon (edited May 25, 2001).]

 

O2 sensor is new.. I just called it the air sensor in my first post. *shrug*

I know the cat's not gutted, because I tried to take it off not too long ago. Damn thing's stuck. I got the exhaust pipe off and could clearly see the inside surface of it. Those things seem restrictive as hell.




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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Are you saying that 220 to 240 degrees is NORMAL for coolant temp? I thought I was running absurdly hot at 230 and turned on my heater to knock it to 215, which I still considered a bit over the limit. I'm getting this reading from a brand new mechanical gauge that's reading from the porthole on the intake manifold to the driver's side of the waterneck.

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1986 Firebird, LG4 305, bored .040 over, Crane cam, Edelbrock headers, Hooker Aerochamber muffler, loud and fast.

"Gimme fuel, gimme fire, gimme that which I desire!" - Metallica, "Fuel"

 

220-240 is a bit hotter than usual, but the hotter the engine is, the more fuel it burns, thus lowering hydrocarbons. I think that's why he suggested that.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

But still, I would contend that you do not need to run hot to pass. I got my numbers while running in early March (about 40F outside), both fans and a Griffen radiator, and a 160 thermostat. I think my temp was around 175F at the time of the test.

Of course, my headers were glowing a little because I was so lean... but my engine temps were about 170F!

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Running hotter will benefit if you need to reduce the hydrocarbons a few PPM's just to pass, especially if the results are very close to pass/fail. My car with the temp at 190 degrees was 64 ppm, at 230-240 was 15 ppm.

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Hybrid Black 5.7L 5 Speed
'95 Competition Yellow Corvette Coupe ZF6