Need a little I/M help!

[MR.CJ-7]

I just went and tested the CJ and for the first time in years it failed. I live in Davis so they just test with the sniffer, no dyno. All they look for is HC and CO at low(1000) and high(2500) rpm.

I passed HC just fine, but CO grabbed me. On the high idle side I read 2.83, they allow 2.00. On the low side I read 4.54, they allow 2.00. The dude running the test didn't have much to offer for tips(he was used to plug and play OBDII systems).

What should I do to make it pass? Lean out the carb? or do I need to get more into it? Any tricks like alcohol in the gas, etc...?

The cap, plugs, wires, rotor are all new. Carb is in good shape, choke isn't sticking. Air filter looks good, but maybe I'll pull it to try and flow more air?

It's kind of ironic, it always passed the dyno in SL county with headers and cherrybombs, I move to Davis and decide to do things legal, put on manifolds, cat, muffler and it fails. Go figure.

Thanks guys!

 

[jdub]

I have been through a mess of issues just like you. I know it sucks but it sounds like you need to take it to a older-car-friendly shop. The downer part is that you probably have paid for his service. I did the same, took it to someone else to tune the carb then take it back to get it tested(since I already paid). When I took it to the other shop to tune my carb they asked why he didn't tune for me in the first place? I paid $20 to get it tuned but learned that you need to lean out the jets almost so there isn't any gas going in the motor then turn the idle speed up-you can go up to 1200rpm that helps your idle speed too. Anyway there are ways to make it work. I had to add a smog pump here in utah county. I have a chevy 350 in my cj7. The biggest issue we saw and this time around is that I needed to change the oil it was dirty so it made it hard to pass. those fumes burn in your carb making it show a filthy reading.

 

[scoutabout]

The machines have a "real time mode" where you can read the stats as you fiddle with things. Find a shop with some friendly. Hook it up and play with idle, mixture, even timing until it appears to meet the specs. Then have them test it.

 

[Dart]

Rubbing alcohol in the fuel tank. It will lower the COs Not alot, and use 91 octane

 

[Rusted]

High CO means that you are getting incomplete/inefficient combustion. Too rich will cause this, dirty plugs, or a weak spark. Also a dirty air filter can cause it (not enough air getting into the mixture). I would put in a few air filter, check/replace the plugs, and lean it just a little.

 

[zukking01]

The machines have a "real time mode" where you can read the stats as you fiddle with things. Find a shop with some friendly. Hook it up and play with idle, mixture, even timing until it appears to meet the specs. Then have them test it.

This is what I did and when I reached the tolerance I ran the real thing and passed. Then when I pulled out I put it back to normal, rich, and drove it home.


DO NOT run alcohol in the vehicle unless you have big jets in your carb. I ran it in a small jet carb and gummed up all the injectors and I had to rebuild it, I passed but my carb died. If you want to put something in the fuel there is a "Pass emissions" additive at checker for around 10-15 bucks and it help out alot.

 

[Dart]

This is what I did and when I reached the tolerance I ran the real thing and passed. Then when I pulled out I put it back to normal, rich, and drove it home.


DO NOT run alcohol in the vehicle unless you have big jets in your carb. I ran it in a small jet carb and gummed up all the injectors and I had to rebuild it, I passed but my carb died. If you want to put something in the fuel there is a "Pass emissions" additive at checker for around 10-15 bucks and it help out alot.

Oh good to know about the jets. ignore my post, just drink alcohol until you pass.

 

[MR.CJ-7]

Well the CJ studied hard and passed with flying colors. I leaned it out, changed the oil and got it HOT. Retest gave up 0.56 high and 0.01 low speed CO readings.

Good for another 365 days...now for the bottle of alcohol!

 

[hambone]

do you drive it regularly? if not take it out on an open road and just open the thing up and then take it right back and test it again. worked on my '80 chev pickup