Topic: Failed Emissions Check

[John Koller]

Hey group,
John in Texas here.  Been lurking for a long while but never speak up much.  Learned a great deal here.  Anyway to my question.  I've just failed my emissions check.  I have a '85CJ7 w/ AMC150 (2.5l), 1bbl carb.
Station dyno'd me.  High speed test at 2345rpm passed w/ good numbers all around.  Low speed test at 1113rpm failed.  HC(hydrocarbons) barely passed w/ 210ppm, standard is 220ppm.  CO failed w/ 3.22%, standard is 1.20%.  This is the area of concern.  To me (fair wrench ability) this appears to be "rich" when idling.  One caveat to this is that I disconnected the "high altitude jumper" about 6 months ago to "lean" it out.  I did this because I was smelling heavy fuel vapors at idle, no other reason.  I'm running heavy magnacore plug wires, champion truck plugs (.045) and accel coil so I don't think it is a lack of fire.  Did disconnecting the high altitude jumper have the opposite effect I was looking for, is this a motor problem, or is this a cat/exhuast sys problem? Any ideas? I have 15 days to correct problem or I'll have to pay for another test.  Thanks in advance.
John

[littleredbeater]

sorry I don't have any advice on your problem but I wanted to ask how you liked the accell coil and mganacore wires? I thought of going that route, any noticable performance change?

[John Koller]

I installed wires, coil, plugs and OEM dist cap all at the same time.  Everything I replaced appeared to be stock.  The jeep only 97k mile on it when I bought 3 years ago.  I wanted to clean up the fuel vapors mentioned above and get rid of a "miss" it was experiencing.  I'm shadetree at best so I figured new wires for miss and hotter spark for more efficient burn.  I got rid of the miss and some better fuel burn. I would have bought a kit if were available (like you see for the newer wranglers) but no one seem to apply all their peices to my engine.  I went w/ Magnacore because they appealed more to me than MSD, Accel, etc.  They are thick, well built, good insulation and appear to be all their "touted" to be.  I went w/ the Accel coil because I a friend that races circle "dirt" track and that is what he swears by.  So far it hasn't failed and seems to work better than the coil I replaced.  Soooo, if given second chance i would not hesitate to use these products again.  I feel like I'm gettting a better accelerator response, smoother idle, and a tad bit more power from this set up.  Hope that helps.

[littleredbeater]

sure does. Thanks.

[Skinny]

Hope this helps, but according to Colorado emissions, High CO is a result of air/fuel mix too rich as you already know and the high HC reading is from unburned or partially burned fuel.  So here are my 2 cents, it sounds like you have done the ignition stuff already which helps, the problem we run into here is that folks use a higher octane fuel thinking it helps, however at the altitude we are at the best option is actually the lowest.  with the thinner air you have less oxygen in the air so all the fuel isn't burned off.   Are you using the lowest grade fuel available in TX? and have you had a good look at the timing or carb adjustment.  If the timing is off a hair then it could also give you a rich run.

[John Koller]

Got any tips on adjusting the carb?  I don't think its a prob w/ the timing.  My idle rpm's aren't high, i get good throttle response, no knocking and it sounds smooth.  Of course this is all by ear, i have no timing light. i'll be adjusting the carb by feel and ear also. thanks

[sharpxmen]

Hi, i am not familiar with your carb so some of the comments might be inaccurate:
Try and put some copper or teflon washers between the fuel valve inside the carb (so the level of fuel in the carb is lower by having it closer to the floater - it will make it run leaner). Try several thicknesses (or add 1 at a time) and see how it runs on the road, you don't want to go to low either. Also make sure the valve closes properly before you do any of this - if it doesn't it will make it rich at lower rpm if it leaks just a bit (which sounds like what you have). I would also suggest buying a carb repair kit which comes with everything you need and give it a good cleaning. There should be also 2 adjustments on the carb that affect the low rpm and partial open throttle mixture: 1 is the idle mixture and there is another one that adjust the mixture when the throttle is partially open. the first one is easy to adjust by rotating it with a screwdriver until you obtain the max rpm with the throttle closed. the second one is a bit tricky but with a little play around you can get a fair result. If you choose to clean the carb make sure to count the turns when you take out these adjusting needles (screws) so you can put them back in the same position to have a relative starting point for your tune-up. Hope this helps.

[dos0711]

I had an old Ford that wouldn't pass. So I drove around the block, leaned it out to the point of shutting off then backed it out just a little so it would idle. It passed with flying colors. I've heard others say that this can be done by pulling a vacuum hose off. FYI

[SMC4WD]

Ok...   I did the search thing and came up with this thread...

I've got a 94 YJ with FI and of course 2.5L.  Yesterday I failed emissions.  Also on the low idle side.  What sucks is that I was soo close to passing (but enough to fail).  The numbers I had were 1.66 CO (%) and I think the limit is 1.2 CO (%).

So I'm going to change the spark plugs, cap and rotor...   I'll disconnect the Turbo City MAP sensor too.  

I'll drive it around so it gets nice and hot, but are there any others suggestions I might try before I use up this freebie?  Like buy some of that 'guaranteed to pass' stuff?  

On a side note: the literature that they gave me (after failing) states:
"Carbon monoxide is partially burned fuel.  CO is a colorless, odorless, toxic gas.  High levels of carbon monoxide indicate that the engine is getting too much fuel, and not enough air.  Here are examples of appropriate carbon monoxide repairs:

Carburetor or fuel injection system repairs or adjustments
Emission control system repairs associated with fuel delivery
Computer air/fuel management and associated components

Note: A carbon monoxide failure during the 2500-RPM mode portion of the inspection cannot be adjusted using the idle air/fuel mixture screw(s).  A failure of this type requires professional diagnosis and repair by a qualified technician. (Authorized Emission Specialist)"[/i]

[chrisfranklin]

My deal is high, out of test range "NOX" levels. Everything else is cool.  Have reviewed it and its probably an issue with the KN cone filter/tube, 4.0 TB, spacer taking too much air which is causing a lean running condition and, thus high NOX.  Everything else has been replaced or checked out -- cat, PCV-valve (mines the other type valve), fuel filter, etc.

My Smog test is coming at the end of this year. Already talked to the guys at Turbo City, who produce a MAP adjuster that may manage the engine to adjust fuel curve to correct lean running condition.  Will drive down to OC and get Turbo City to do the install and tuning and test until emissions acceptable results are obtained.  

In addition, will likely have to buy a YJ4 type "airbox" to do the emissions test.  But, heck, that in itself will probably do a lot to fix the NOX problem, due to the more restricted air-flow it causes; and, of course, torque with it is better, brake booster will work properly -- though mine is fine now.  May try with just the airbox. :idea:

[chardrc]

this makes me glad we no longer have emisions tests in minesota... soory that i dont have any usefull information but a person i know has a cj7 with a 6cyl and he used to always fail emitions so we had to disconect something and make it run like crap to get it to pass and thenm just switch it back to normal..