What octane gas do you all use in your Camaro? The guy who sold me mine said he has been using Plus since it is a sports car. I didnt see the real reasoning behind this logic (and I do understand what the higher octane does ). So I've been using 89 octane like he has been using. But I went through DEQ and failed it horribly. I changed the plugs, plug wires, rotor, dist. cap and put in synthetic oil. Poor Fred has been runnin off of crap oil (yes, I named my car Fred )

I'm going back to DEQ tommorow to try it again (with a bottle of fuel injector cleaner in the tank) to see if it'll help. But I cant help but wonder if 87 octane would be better since it would be easier to ignite the fuel? Or would I be getting a pre-combustion problem?

BTW, I'm running a completely stock 1986 305 Carb'd Berlinetta

 

BTW, this is what my DEQ test results were

THX g/mi MAX
STANDARD:2.00
READINGS:3.56
RESULTS:FAIL

NOx g/mi MAX
STANDARD:3.70
READINGS:6.95
RESULTS:FAIL

CO g/mi MAX
STANDARD:32.0
READINGS:10.5
RESULTS:PASS

CO2 g/mi
STANDARD:N/A
READINGS:663.8
RESULTS:N/A

Fuel Use MPG
STANDARD:N/A
READINGS:12.75
RESULTS:N/A

Avg HP/EXE
STANDARD:N/A
READINGS:12.90
RESULTS:F124

Passed Noise and smoke as well.

 

Well I was running 87 octane in my car when I first got it but my uncle had a scanner and it showed it was knocking on occasion and I wasn't happy with me but he was like "oh your car is just old, its normal" (HE'S A MECHANIC! Its like he really doesn't want to help me on my cars at all...anyways....). I read on here in a thread similar to this one awhile back that the owners manual says to use like 91 octane or something. Well, I put in the top grade a few times, but now I've been putting in the middle grade. Actually the other day I put the low stuff in because I had $6 and had to get home Tomorrow I plan on running 93 for the track.

 

In the manual it suggests 87 octane, 85 in colder temperatures, or if available in your area. This is mainly what made me ask. Was your car stock when you took those readings? I know that the Berlinetta doesnt have the performance drivetrain (or that's what I've been told atleast)

 

Use whatever fuel your car gets the best fuel economy with.

As far as emissions are concerned it kinda looks like you have a lean condition, althought it can also be anything that could cause a misfire along with a failing egr system.

 

Looks like it was rich to me.

What you did will probably help. Running higher octane for the test may help.

Since you failed both hydrocarbons and nitrogen oxides, you probably have clogged EGR passages in your intake manifold. With the tune-up and oil change, it may reduce the hydrocarbons enough to get those to pass. You may be marginal with NOx.

When stock, mine had trouble passing. Changing valve stem seals helped. I discovered as I started modifying that the intake EGR passages were plugged. Fixing that alone reduced the octane need (pinging). And, with the mods, it sailed through the emission testing.

 

Think the high test will help the NOX a bit, slower burn. Oil change might be the bigger help too. Make sure that EGR valve vacuum line is plugged in.

 

I meant to say, "...with the mods, it sailed through the emission testing with regular unleaded."

 

Thanks guys. I put some of that STP cleaner stuff in my gas when it was just about full, I thought that would clean the intake? lol. So I went through DEQ again today with the tune up and oil change, and this is the results.

THX g/mi MAX
STANDARD:2.00
READINGS:3.89
RESULTS:FAIL

NOx g/mi MAX
STANDARD:3.70
READINGS:7.82
RESULTS:FAIL

CO g/mi MAX
STANDARD:32.0
READINGS:10.7
RESULTS:PASS

CO2 g/mi
STANDARD:N/A
READINGS:695.7
RESULTS:N/A

Fuel Use MPG
STANDARD:N/A
READINGS:12.37
RESULTS:N/A

Avg HP/EXE
STANDARD:N/A
READINGS:12.90
RESULTS:F124


so the lady in DEQ said to drive it for atleast 10 miles and come back. So I drove it to the nearest city (about 8 miles away) and then came back (another 8, so 16 miles in the trip), went back in, and these are the rest results


THX g/mi MAX
STANDARD:2.00
READINGS:4.66
RESULTS:FAIL

NOx g/mi MAX
STANDARD:3.70
READINGS:5.27
RESULTS:FAIL

CO g/mi MAX
STANDARD:32.0
READINGS:24.1
RESULTS:PASS

CO2 g/mi
STANDARD:N/A
READINGS:59.2
RESULTS:N/A

Fuel Use MPG
STANDARD:N/A
READINGS:14.41
RESULTS:N/A

Avg HP/EXE
STANDARD:N/A
READINGS:12.90
RESULTS:F124


Does this mean I need a new Cat? The only thing that seemed to get better was my fuel use and NOx


How can I un-clog an EGR passage? Do I have to take off my air cleaner, carb, and intake manifold and meticulously scrub in the passages in there? or is EGR something in particular lol. I'm kinda a noob here so if you could lead me to a picture of what it looks like I would be greatly indebted to you

 

The only way is to remove the intake manifold.

I don't have a picture (might be able to come up with something later). Typically, there's a big baked cake of carbon in about a 1" square or so hole (some of the passages are smaller). You don't have to "scrub" them, you need to take a screwdriver to them and knock a hole in the crude.

The fact that it got worse after the tune-up and after driving it around is a little scary. But, having a vehicle that wouldn't pass ('84 full-size van), and didn't improve with the "standard" guideline repairs, I bucked the tide and replaced the cat. Breezed through the next test.

 

i thought it was a little scary too. And I also cringe at how sucky that gas mileage is, we're supposed to get 17MPG in city arent we? I was going all freeway basically and got something around 12-14MPG.

I guess I'll look into a new Cat. Can I get one from a junkyard off another F-Body, and have the price of the welding in be considerably less? I seriuosly dont have the funds to pay for a new cat, along with new plate, new title, and tags lol. I

s there any way to trick the emissions? lol. I think that the Q-Jet carb is like stuck or something so i cant change how lean or rich it is. Someone said it was done like that from the factory?

 

It is illegal to sell used catalytic converters.

They definately don't make the carb run rich from the factory. The carb self-adjusts. It uses an oxygen sensor (O2 sensor) in the exhaust to tell the computer if the mixture is lean, and adds more fuel based on that data. It is possible that your O2 sensor is weak and causing the mixture to go rich (that's the default mode). That usually makes NOx go down, however.

The O2 sensors are relatively inexpensive. If that doesn't help, then you're probably looking at a cat replacement.

 

okies, many thanks for the help, I appreciate it