Kalifornia Smog Fail - Help! (1 Viewer)

[CruiserStuff]

Hey Fellow Mudders -

This is the first time I've tried to smog the vehicle since I put the used 2F in that I bought from Georg. It really runs nice!

Just took the 40 to the smog shop...fail.

The tech said that I need carb adjustments. He said that it is running lean at idle that might be causing a misfire. He also said that it is rich at off-idle. The CO is high at off-idle (running speed) and Hydrocarbons are high at idle.

He didn't give me a print-out so I don't have any numbers. Whatever thoughts you guys have would be greatly appreciated.

BTW, the Cruiser was hot and I'd put a quart of denatured alcohol in the tank full of premium. Don't know if that factors in or not.

Thanks in advance!

 

[fyton2v]

Hey there. Check out this thread. OK you carb experts

Make sure you fix vacuum leaks. Kinda hard to do since they aren't visible, but if you're unsure if your vacuum system is plumbed correctly, check out your FSM. You may need new tubing. My fed spec 40 passed CA smog last year. It's stock and has all the original smog gear. Good luck.

 

[Pighead]

Lean idle miss is easy to fix, you have an idle mixture screw...turn it out a bit until the miss goes away.

 

[CruiserStuff]

@fyton2v - Thanks for the response. I'll check the vacuum lines, but I'm not thinking that's the issue here. Can't hurt, though, that's for sure.

Pighead - Okay, cool. What would be a good way to tell when I've turned it out enough? Honestly, I can't hear the miss...

 

[fyton2v]

Check out the 3rd post from treeroot in that link above. He tells you how to set your idle mix. It's interrelated with your idle, and vacuum. Make sure you timing is at spec too. There are many knowledgable people here that can help with this topic. People who know a heck of a lot more than me. I just fudged with it until I seemed to find the right balance between idle and vacuum. For my truck I couldn't get higher than 17-18 inches of mercury.

 

[CruiserStuff]

Yeah, that's a great link...thanks very much! Yes, I'm sure I'll get there...hoping to do so without a carb rebuild!

 

[Pin_Head]

Lean misfire may also be due to an intake manifold vacuum leak. Rich “off idle” is not a measured CA spec, which only measure at 1500 and 2500 RPM. The high CO could be due to a stuck power valve piston or a lack of vacuum at the PV port (assuming you still have the ‘76 carb).

 

[CruiserStuff]

Hey Pin_Head - Thanks for chiming in! Yes, I do still have the '76 carb. Which is the PV port?

To check for an intake manifold vacuum leak, what do I need to do?

And, what do I need to do to determine if the power valve piston is stuck?

I'll start searching here to see if I can find the answers...

Thanks very much!

 

[Pin_Head]

The PV port is the brass tube at the top of the air horn facing forward with the number 10 in the casting. This needs vacuum to close the valve. Normally, it is operated by the VSV which is driven by the engine computer. Opening the valve substantially riches the mixture. Pull a vacuum on the PV port and see if the idle speed changes compared to no vacuum. If it slows with vacuum, the valve is working. IF the VSV isn’t working, check the connector for the computer by wiggling it with the key on. If you hear the VSV clicking, then the contacts for the connector to the PCboard are broken and need to be resoldered.

There are lots of ways to check for manifold gasket leaks. Spray carb cleaner or propane gas around the sealing surfaces; particularly on the underside that is hard to get to. If the idle speeds up, you have found the leak. There are several other possible sources of leaks, like the brake booster, PCV line, EGR valve (on 79 and up only) and a cracked manifold.

 

[CruiserStuff]

Thanks Pin_Head - Will pick up some carb cleaner spray and will start looking. Will report back...