81 accord hatchback smog issues
 

Hi I just recently got a 81 accord hatchback to be my daily driver. I got the carb cleaned up and tuned and it runs good. Went to get a smog cert. and it failed badly. Really high nox and not great on hydra carbons either. Any suggestions before I start the long process of going through the emission systems one by one.

Re: 81 accord hatchback smog issues
 

So I've done some work on the car and some research. It appears that I need a new anti afterburn valve and the control boxes on the firewall need some attention (i.e. Solenoids/ hoses). If anyone knows where to get these hard to find parts or has some they would sell, I'd be grateful.

Re: 81 accord hatchback smog issues
 

high nox is usually a non operational EGR valve, either the valve or passage are plugged with sooth or caked hydrocarbons or the control hose is disconnected, or the thermovalve is non op.

can you post a scan of the smog test 15 and 25 mph datas?

How many miles on the engine, stick or auto

those black boxes are a real headache, but start with the easy stuff before:

1) Check EGR operation, pulling the bellow with finger the engine at idle will miss then stall... so the passages are clean is no stall then time to open the passages in the intake manifold, coat hanger will do -not too familiar with the 81 models, but a net search gave this

http://repairguide.autozone.com/znet...5280251830.jpg

or it is like the 84 years

http://s3.amazonaws.com/rparts-illus...4863c0516d.gif

2) Then timing, too much timing will raise nox and HC, so a way to pass smog is to lower your timing to the lowest accepted value as per the hood sticker minus 3 degrees of the posted data, for Calif -you are in Calif to have to pass smog with an 81 model-

Those engine are real lean so the nox is always very high.

Re: 81 accord hatchback smog issues
 

Here are my smog papers. I tried twice. The carb was tuned and a ball bearing was put in to bypass the anti afterburn valve. To get it to idle better.
https://cimg4.ibsrv.net/gimg/honda-t...4e98780762.jpg

Re: 81 accord hatchback smog issues
 

I was able to replace the anti afterburn valve or one shot valve. Car runs really good now. I replaced the EGR Valve too. Now I'm going to check the passage way by testing the bellow. Hopefully all goes well. Also gonna retard the timing 2-3 degrees to help a little.

Re: 81 accord hatchback smog issues
 

The HC is the amount of unburn gas and a lot is not being burn, bad spark plugs, cap / rotor,

How are your spark plugs, cap, rotor and wires in that order?

Also the timing is way off, if the report is correct at 1 BTDC, it needs to be increased, I do not have the specs, but ballpark should be between 15 and 22, you need to have access to a timing light . A sticker on the hood should label the amount of timing...

Here is a cheat sheet:

https://cimg6.ibsrv.net/gimg/honda-t...7e1e97bcff.jpg

Depending on your skills you could go to a gold start smog station, they are certified to do repairs to allow you to pass smog, Not cheap... but could be less than dumping parts. The last time I used the gold star labelled smog station, they did the wrong diagnostic... so nothing is foolproof.

Re: 81 accord hatchback smog issues
 

He letank. I just swapped out the plugs for stock ngk's. The cap, rotor, coil, wires look new. I don't what quality they are, but they look less than 6months old. I went to an exhaust place about a week ago to get the cat replaced and they did a pre smog test and said I'm not getting any vacuum from the egr. About 1psi. As for timing the service manual I got from eBay says timing should be TDC for the California 5spd manual model.

Re: 81 accord hatchback smog issues
 

if the egr is not getting vacuum signal, we need to figure out where to find one. I did the same for a neighbor's subaru and he passed smog, he had the schematics of the vacuum system
Not too familiar w the 81 accord, but it must be very close to any honda engine from that era.
The signal is carbureted ported vacuum, meaning no vacuum at idle, but as soon as you open the gas the throttle plate open up and you generate vacuum.
Probably on of the thermosensor on the intake manifold is non op, so ideally we need to pick the hose before the thermosensor. The engine might a bit reluctant when cold if you live in Michigan but for Calif, it will be fine.
Do you have a black box on the firewall with a bunch of rubber hoses.
Last year I could have access to an 80ish accord, but it is gone to the crusher now...

Picts of the engine bay could help

Re: 81 accord hatchback smog issues
 

Ok I'll take a look at the thermosensor. It only has one for my year I believe. I'll take a pic of the schematic under the hood tomorrow. Also yes I have the dreaded black boxes (3) against the firewall. When I was at the junkyard, I was able to get thermosensors off an 82 accord. Plus all of its solenoids incase any of mine are bad. I've noticed it's become very hard in California to find early 80's Hondas to part out at junkyards now. Thanks for the help man, really appreciate it.

Re: 81 accord hatchback smog issues
 

https://cimg5.ibsrv.net/gimg/honda-t...4cdb4e96a1.jpg


https://cimg7.ibsrv.net/gimg/honda-t...be41317ecf.jpg


https://cimg8.ibsrv.net/gimg/honda-t...5f648e5559.jpg

Re: 81 accord hatchback smog issues
 

Here is the schematic under the hood for the emissions and I took a pic of the engine bay

Re: 81 accord hatchback smog issues
 

it is the same headache as the 86.
If you have access to a vacuum gauge, it is a good time to see if you can find vacuum from one of the easiest to unplug hoses. Remember that the hoses are almost stuck to the nipples which are sometimes plastic and will break. With a small pair of pliers you can rotate the hose around the nipple gently -ah, ah, ah sounds kinky!- to loosen it.

If no vacuum gauge, and your hearing is good you can try to feel the rush of air, which should happen only when the throttle is applied, not at idle to control the EGR.

try to see if you can test and find hoses #4 , #3 or #E , #E turns to #15 to one of the EGR control box.

Usually Honda number the hoses every few 3 or 4" so you can track the hoses route, not easy.

If you have a picknpull junkyard next to you, you can search their website for inventory picknpull.com and go practice there.

If I can think of something I'll post latter.

Re: 81 accord hatchback smog issues
 

ONE MORE DO FIRST you need to see if you have a major vacuum leak, use some carb cleaner or brake cleaner or WD40 and spray around the base of the carburetor to find any cracked hose(s), if the idle goes up, you have found a leak, the NOX level of 4300 ppm is also an indicator of a vacuum leak. The back of the carb has the vacuum manifold, and that can be tricky ... also your brake booster could be leaky....

this was my problem, and like you, I was pushed to a new cat that was not needed, remember that if you spend over $500, and it was recommended by the certified smog tech, you can ask for a 2 year waiver... this will include the visits and others.... you need to make an appointement with the smog refereee, usually at a local community college...


https://cimg1.ibsrv.net/gimg/honda-t...1253c65ab6.jpg

and the subsequent result


https://cimg6.ibsrv.net/gimg/honda-t...cc978d14d4.jpg

Re: 81 accord hatchback smog issues
 

https://cimg0.ibsrv.net/gimg/honda-t...58a6939303.jpg


Noticed hose line 4 is split. Could that be the culprit?

Re: 81 accord hatchback smog issues
 

https://cimg9.ibsrv.net/gimg/honda-t...fdd7f35a36.jpg


Found this piece of plastic in vacuum line 2 witch goes to vacuum switch to the carb. Is that supposed to be there? I also pulled a ball bearing out of line 20. Needless to say I'm goin thru all the vacuum lines to what else is jammed up with crap.

Re: 81 accord hatchback smog issues
 

So after removing the ball bearing from vacuum line 20 the car ran rough. I have it some gas and upon the rpms coming back down the car stalled out so I think one of my solenoid a is not working. That line goes between the vacuum holding valve a and get control valve a.

Re: 81 accord hatchback smog issues
 

My bad that line goes to the vacuum holding valve a and the purge control/unloader valve

Re: 81 accord hatchback smog issues
 

So I hooked up the vacuum gauge to the line that goes to the egr. There was no vacuum at idle. The service manual says to bring Rpms to 4500 after starting car and that there should be no vacuum. It pulls 2-3 hg's. It says if vacuum is present then either the erg solenoid a or thermosenor a is not working. I tested the solenoid with a 9v and it fires. I tested for voltage at the connector with the key on and it had voltage. I also checked the wires at the connection of the thermosensor a and thermosensor a and they both have continuity. So I'm kinda lost and don't know what's going on. Am I missing something?

Re: 81 accord hatchback smog issues
 

That can be a source of vacuum leak. These short hoses are a pain to replace, and the honda quality is the best, the replacement vacuum hoses from the usual store are not as good. On my last junkyard foray, I grabed a bunch of those labelled honda hoses. You can lubrify the hose w a dab of water, wd40...

DId you try to spray wd40 or brake cleaner around the carb before ?

Re: 81 accord hatchback smog issues
 

Looks like the end of one of the thermovalve controlling the distributor advance hose #2, this is why they put a ball bearing to prevent vacuum loss.

You are courageous to pull all those hoses...

I have a bad thermovalve and went to the junkyard to see how hard they are to remove, I broke all of them, the plastic is brittle due to heat, the CVCC engines are really lean and run hotter...

The EGR has so many redondancies that it is difficult to test it. I have the shop manual for the 86 and did the procedure as described, that was the only way to figure out which component was fubar.

When looking at the schematic, picking up the line that feeds to the vacuum holding solenoid valve B, # 14 could be a solution. Of course that holding solenoid is getting vacuum from line #19... which has a check valve.

Re: 81 accord hatchback smog issues
 

in fact 2 choices for vacuum, either the blue line #14 or the green one #11


https://cimg1.ibsrv.net/gimg/honda-t...4f2ed0d798.jpg

Re: 81 accord hatchback smog issues
 

I didn't have a chance to do the carb cleaner yet. But I did notice the gasket between the carb and the air cleaner is not there.

Re: 81 accord hatchback smog issues
 

that is not too important.

Re: 81 accord hatchback smog issues
 

Found this at the local junkyard while I was getting other parts, already gutted, so you can see #11 or #14, but #11 is more likely to be the ticket for vacuum source, for accessibility.


https://cimg4.ibsrv.net/gimg/honda-t...a27dfc8623.jpg

Re: 81 accord hatchback smog issues
 

Ok thanks, I'll take a look this weekend. Had to put the car aside for a minute to fix my roof on my house.