Emission contol problems

[robaroni]

Hello,
New here but seasoned mechanic.
I'm working on my mom's Honda that she left me. It's a neat car (84 Hatchback DX, auto)
First, I'm wondering what kind of mileage the people here are getting? My book says ~41 highway but my mileage seems to be in the mud! (20 to 25 mpgs)
I gave this car to a kid as a present because he needed a car but he didn't appreciate it so I took it back, it only has 37k on it and the body is good.

I started going through the emission control system and found a bad vacuum advance on the distributor so I changed it out. I also had to put in a new head gasket as the kid overheated it and blew it out.
It idles well but when it's cold it takes a long time to return to normal idle, the engine has to be completely warmed up. I found a bad choke opener diaphragm and changed it. Now i found a bad "vacuum control valve". I checked the vacuum on the other valves and they all seem good. I also chanves out the O2 sensor.
I have the Honda official manual but my hood decal calls the valve the "one shot valve".
I machined the end of the valve off and as I expected the top diaphragm is bad. I have not machined the lower part of the valve off to see if those diaphragms are bad but I'm thinking about finding ways to circumvent the system at least partially because getting these parts, as I'm sure most of you know, is a bear!
Which leads to my next question, does anyone have a good source for parts on these emission systems?
Thanks for your help and glad to see these old Honda's are appreciated. My mom loved hers.

Rob

[Dr_Snooz]

Welcome! I hope you slapped that kid upside the head! I owned an '82 Accord, which was the 2g body style. However, it shared most of its parts with the '81 1g Accord, including the CVCC engine. If memory serves, there was a pretty significant redesign in '84, after which the parts resembled the 3g more. All that to say that 20-25 was about right for my '82. My 3g consistently makes 28-32. If you have a CVCC engine, then don't hope for much more than what you're getting. The CVCC made good smog numbers, but they came at the expense of fuel economy. If you are looking for OE parts, check with http://www.hondaautomotiveparts.com/. The OE parts are getting scarce, though, so you'll be doing a lot of rummaging at the junkyard and reconditioning your own parts. It's always nice to welcome another member putting effort into these cars.

Incidentally, where are you located? If you're working hard getting the smog stuff working, then it can only mean you are located somewhere (like California) where that is important. Is a CA smog check in your future?

[robaroni]

Welcome!

Hi,
thanks for the reply. I live in the Catskill mountains of NY and the car passed inspection. I figured if I made it run to factory specs it would start showing some of the figures the book says. (41 hwy). I know that they had a different method back then but I figured this car would get me into the 30's at least.
It runs really well since I did the head gasket, changed the two bad diaphragms. I just rebuilt a third one that I just couldn't find one anywhere in the country. I'll try the link you posted (thanks).

I'll post the repair to the control valve in case anyone wants to tackle theirs. I advise getting one of those vacuum test pumps like in the Honda Manual. I got mine on Amazon for 25 bucks and went through all the dash pots on the engine after I found the first two bad ones.
I'll run a couple of no context posts so I'll have 5 to allow me to post pics.
Rob

[robaroni]

Picture post access.

[robaroni]

Picture post access

[robaroni]

Picture post access 4

[robaroni]

Here's the valve I just rebuilt: (photo 2 shows the machined valve assembled)

[robaroni]

I believe today I found the last carb/ emission problem. Maybe some of you are experiencing this problem and if you are your mileage will suffer greatly. If you start you car when it's warm after sitting about 10 or 20 minutes the idle should not race for an extended period.
My car took a long time to settle down to idle from a cold engine. The temp had to be almost a third of the way up the scale before it would idle down. If I went into market or store for 15 minutes it would race until it warmed up really well.
If you look into the carb barrel closest to the windshield you'll see it dripping gas into the venturi and this will wreck your mileage. What you want is for the system to settle down immediately as this wastes the least amount of fuel. I checked the fast run diaphragm and it was OK, finally I had to drill out the choke rivets and I found the choke position needed to be changed slightly to allow the diaphragm to release the fast idle.
I'm going out now to recheck it from cold but the last time I checked it, it was good.
Now I'll l see what this car can do for mileage. I noticed when the car warmed up it would sip gas but once I stopped and restarted the gas level would drop... We'll see what the mileage is now.

By the way, I really went through this engine. I used to tune 911 Porsche's and I'm a good mechanic. I adjusted the valves and this engine now runs like little sewing machine. You can't tell it from a new car. This poor guy has been abused by so many poor mechanics that it took me a couple of months to get it back in shape. Some guy even changed the timing belt, why I have no idea. Not only that he replaced the belt off a cog and never replaced the valve cover gasket. Then he told my mom she had an oil leak. Yea, she had a leak, he caused it!
Rob

[Dr_Snooz]

Nice job getting things sorted out. You definitely know your way around an engine compartment. Post pics of your car when you get a chance.