Help emissions failure, bah! fail HC at idle Options

[TravisNeff]

Well, I tuned up the 914 (72 1.7) and drove the hell out of it before my emissions test. It failed HC at idle, here's the results:

HC
Loaded Reading: 123 PASS
Loaded Standard: 400

Idle Reading: 431 FAIL
Idle Standard: 400

CO
Loaded Reading: 0.27 PASS
Loaded Standard: 4.2

Idle Reading: 0.30 PASS
Idle Standard: 5.50

I set the ECU all the way counter clockwise and adjusted my idle to around 1100 for the test. Maybe I set this the wrong way? I set it per Brad Anders' webpage suggests. Or maybe TPS?

Since I passed so well on the others, I don't want to undo what I did right for my idle test. Could be a vacuum leak I have a 200-300 rpm hunt - hoses check out so I am left with plenum gaskets, cold start gaskets or a cracked plenum.

Gimme some ideas!

[Aaron Cox]

you have to smog a 72? (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

[phantom914]

HC is unburned fuel. If you lean it out too much you can have misfires which will dump raw fuel. Judging by the CO readings, you can afford to richen the idle a bit if that helps you have a smoother idle (less misfiring). The ECU knob only affects idle so it won't mess up the loaded readings.


I have also seen the suggestion in the past to set the idle speed on the high end of the acceptable range.


Andrew

[TravisNeff]

Yeah, have to test back to 1967 here in metro Phoenix, it sucks!

It was popping a little bit, I can adjust it out - wish I had a meter to tell when I am close.

[Aaron Cox]

unburned fuel...

get a CD ignition (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) 4 sparks instead of... should take care of it..... (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[TravisNeff]

That was my first thought, don't wanna wait for shipping and stuff - gotta be legal to make WCC, or I can get a 3 day pass

[Aaron Cox]

QUOTE (Travis Neff @ Apr 14 2005, 12:51 PM)

That was my first thought, don't wanna wait for shipping and stuff - gotta be legal to make WCC, or I can get a 3 day pass

local speed shops man.... youll need a tach/Fi adapter too adapter

[lapuwali]

With an allowed 400ppm HC, you don't have to be very close. Richen it up a fair ways. You might also turn the idle down a tad, and make sure you've got a fully tuned up car in all other ways. Get your timing spot on, and get the valves just right. There's little reason a nicely running 1.7 shouldn't pass '72 requirements with ease. You're so far away on CO, it's probably running super lean. You should be running 2-3% CO, you're allowed 4-5%, and you're running under 1%. If you tune the car so it's running sweetly for you, it will very likely pass.

[Joe Bob]

Could be the CHT....bets to get a shop and put it one the scope and try and tweek it while it's running. If the CHT is not functioning it tells the ECU that the engine is still cold and makes it run rich at idle....you can lean the idel out...somewhat with the knob on the ECU.

[TravisNeff]

I count 22 click on the ECU, I was at full CCW and adjusted to it 11 clicks (middle), adjusted the idle speed to 1200 hunts a little less maybe 100rpm, fixed a cracked intake boot while I was at it.

You think setting the idle speed down will help? I seemed to read that you need to run it as high as possible - I'll lower it down and let it idle for a few minutes to see if that hunt lessens

[TravisNeff]

I also disconnected the TPS and there was no idle speed change, so I am good at idle for that (and it doesn't buck when running, so I should be good there).

[bryanc]

QUOTE (Travis Neff @ Apr 14 2005, 12:29 PM)

I count 22 click on the ECU, I was at full CCW and adjusted to it 11 clicks (middle), adjusted the idle speed to 1200 hunts a little less maybe 100rpm, fixed a cracked intake boot while I was at it. You think setting the idle speed down will help? I seemed to read that you need to run it as high as possible - I'll lower it down and let it idle for a few minutes to see if that hunt lessens

Weird, I just failed emissions yesterday. The worst part of the experience was seeing the naked guy running down the street on my way to the emissions place. (IMG:http://www.914world.com/bbs2/html/emoticons/monkeydance.gif)

Anyway, a higher idle is better. The measurements are done in PPM and percent, not volume of gas. A good idea is to get an oxygen sensor and gauge and use that to set the mixture. On my car, if the mixture is right, it passes easily. If it's off slightly, it fails miserably.

[MarkV]

Mine always fails the first time for high HC. Bump the idle up to 1100 RPM and install a set of Bosch platinum plugs, the HC reading goes down to like 250. We have a weak ignition system that makes for a dirty idle, platinum plugs fire at a lower voltage & clean up the HC at idle.

Then you take it home and reinstall regular plugs and lower the idle back down. (IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif)

[TravisNeff]

THANKS ALL!! (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif)

IT PASSED - WOO HOOOO!

I ran the ECU mixture know about 1/2 way adjusted idle to where it woulnd't hunt (about 1050) and held my breath. Had to shut the car off on the dyno and didn't want to restart - got freaked at that. First test they ran it up to 3rd gear, 2nd time through he only did it in 2nd gear. Then when the test was done they were going to do some random testing, where they track the car under various load conditions. I thought I was fucked. They decided not to do it, and I pulled forward expecting that I failed again - but NO - I passed!

Loaded HC 87 (standard 400)
idle HC 389 (standard 400) - barely passed
Loaded CO 0.19 (standad 4.20)
idle CO 2.42 (standard 5.50)

Giddyup!

[jim_hoyland]

When my '75 was last smogged it would always pass in 2nd ( or was it 3rd ? ), and always fail in the other gear.

Why is that ?

[TravisNeff]

All happy after her report card... Just need to work on the wheels, tires have a baaad balance problem on them or I have a bent wheel. I think I like the westerns on this car more than the enkeis.

[jasons]

Hey Travis, did you have to sit in the car and shift it for the F'ing morons at the emissions place? I hate taking my car to those goons. In 5 years, I have come by one guy who could shift the car. And thats going twice a year cuz I typically fail at least once.

Oh well congrats on getting through. I hate that F'ing tax collecting $hithole emissions program. My car is 32 F'ng years old, I drive it only for leisure, and I have to pass emissions every F'ing year. OK Rant Over (IMG:http://www.914world.com/bbs2/html/emoticons/givemebeer.gif)

Your car looks good BTW

[TravisNeff]

Thanks Jason.

I sat in the passenger seat and had to help them get it into first gear each time, of course they pulled it back out of gear and put it in 3rd. I giggled when they put the fan in front of the car to cool the radiator. If I get the option to get tags for 2 years and skip next years test - I'm all over that..