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240 Need some K-Jet help, high HC on smog test

drj434343

drj434343

Member
Joined
Feb 22, 2010
Location
Portland, OR
I recently failed smog testing in Oregon. These are state run test centers that only test CO2 and HC at idle.

The car: 1980 Volvo 242. Rebuilt B21F with 20K miles, shaved head and deck with estimated ~10.5 CR. Stock K-jet; new harness, vacuum lines. O2 sensor and 1 level colder plugs with 10K miles. Recently installed K cam installed straight up. CAT has 20K miles.

The test: HC - 220 max CO2 - 6 min
Idle 1 HC - 324 CO2 - 9.7
- Car failed first test, so the techs revved it for 20 seconds and then retested at idle -
Idle 2 HC - 462 CO2 - 8.3

I'm familiar with the common HC fixes; vacuum leaks, spark plugs, O2 sensor. However, because my high CR B21 has always been a little loppy with K-Jet (made worse by the recent K cam change), I'm hoping to get some K-jet folks to chime in.

Timing is set to 12 deg. Idle set to 1050, any lower and loppiness gets to be too much. Dwell shows 85 at idle, but idles even worse if adjusted any lower. As a testament to the O2 function; if unplugged, dwell slowly drops until the car dies at around 20 dwell.

So, I know there a number of tune issues here. I've been driving it for the past 2 years with a B cam advanced 2 deg and successfully passed smog with that combo and a slightly smoother idle.

I'm hoping to find a way to pass with the K cam and K-jet, but I know I'm at K-jet's limit with this setup.

Thoughts?
 
What's the vacumm pulling at idle?
What's the fuel pressure?
 
K cam has lots of overlap, unburnt fuel passing straight through, especially at low rpm. Raising the idle (if you can do that with your smog rules) should drop HC. If its just an idle test, put some hotter plugs in for the test only?
 
3mm screw adjust

My 82 244 I used to own went from a gross polluter to passing smog with just a tweek on the K-jet mixture screw.
 
No mention of what CO looks like in your test....

How nice are injector spray patterns? I have the tool to clean them.... or replace with new if really icky.
 
It should pass no problem.
Adjust the CO screw.
That's assuming you "stage zeroed" it. Injector seals, intake gasket... :blah:
 
JohnLane said:
No mention of what CO looks like in your test....

How nice are injector spray patterns? I have the tool to clean them.... or replace with new if really icky.
Click to expand...

CO showed as 0.00 in all the tests, though there was a spot for it. I'm not sure if they didn't measure it or what.

Injectors have all been spray tested and look excellent. All new injector seals, etc. Basically new everything during the full rebuild. Passed with flying colors 1.5 years ago.

To the previous questions, I will measure vacuum tonight, but am at least a few days from measuring fuel pressure.

I'm wondering if the K cam could be the culprit with it's overlap as previously suggested. This same setup has passed smog with flying colors, the only change being it was running a B cam before. I guess I never imagined that cam change would make such a huge difference.
 
Jesus, just put in an M cam and be done with it. Swap the K back after you pass.

There's a reason Volvo fitted K-cam cars with pulse air, to inject fresh air into the exhaust and help with unburnt fuel, along with a totally different ignition curve (5 degrees advance base timing), cylinder head etc.
 
Thats it.
My car ran clean and idled smooth with B and K grinds.
You have other issues.
If it cant be tuned out, do what the Canadian says.
 
poulson01 said:
Thats it.
My car ran clean and idled smooth with B and K grinds.
You have other issues.
If it cant be tuned out, do what the Canadian says.
Click to expand...

Idle got noticeably worse just going from B to K, so there definitely is a difference from the overlap change.

I do have a distributor from a B23E high CR Canadian model, presumably with the K-cam that I may try swapping in.

Is yours high CR as well?
 
Last edited:
I junked it years ago.
Stock B21F
You can't just throw a K grind in without tuning for it.

Both vids are stock tune without changing anything but the cam.

<iframe width="420" height="315" src="//www.youtube.com/embed/YxAXEgHgtlg" frameborder="0" allowfullscreen></iframe>

<iframe width="420" height="315" src="//www.youtube.com/embed/M6M6P_YFUbU" frameborder="0" allowfullscreen></iframe>
 
Posting a follow up for anyone else doing a smog search. Changed B cam back in and passed with flying colors. No other changes to the car.

K Cam HC values 324 - 462 PPM
B Cam HC value 139 PPM
 
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