Emissions Failure
 

Hi all,

I haven't driver the '93 Jimmy much lately because I'm primarily running the '98 and the '93 needs a new transfer case input shaft seal. Since the registration is up at the end of the month (Monday) I took it out for an emissions test. It failed. Here's the specs:

1993 GMC Jimmy 4.3L VIN W
Hydrocarbons Limit: 400 Cruise Emissions: 243 Pass
Hydrocarbons Limit: 400 Idle Emissions: 918 Fail
CO Limit: 3.00 Cruise Emissions: 5.89 Fail
CO Limit: 3.00 Idle Emissions: 9.03 Fail

So the truck is high on HC at idle and high on CO both at idle and at cruise. How do I go about solving this?

at work what we do if it barely fails on hydrocarbons, we retard the timing by a few degrees, remove the air filter and retest it. sometimes it works sometimes it doesnt.

just had a 1979 pontiac boat in there the other day, forgot the exact kinda car. but it failed 1500 on hydrocarbons and needed like 350 to pass, after the timing was adjusted and air filter removed it brought it down to 900 but still failed. boss messed with something else, screwed it up even more casue it went up from the 900 to 1200.

so put a new catalytic converter under it and it passed crazy good, only put like 40 or something like that.

so you can try the ghetto way of doing it with the timing, or maybe do a tune up also if its due, remove the air filter and run it. i plated my junk in illinois. anything under 95 has no emissions

toby,

clean the egr,and maybe replace the cat. and get a bottle of that "emissions testers" stuff. we dont have testing here. i dont know if that stuff works or not.

My first thought was the catalytic converter. It runs very well and has new injectors from 2010 so I highly doubt it's actually getting too much gas.

Can I actually adjust the timing on this truck? I know I can adjust it when the timing lead is disconnected but once I reconnect it won't the computer just try to adjust it back to where it was?

on a 93'? as long as you disconnect the timing wire,adjust and reconnect it wont redo its self.

OK. I may try that over the weekend. I'm full up on Oktoberfest gigs this weekend so it may have to wait until Monday morning and a last-minute retest. I'll report back either way and let you all know how it turned out.

Update: I didn't do anything with it for the past month because I've been busy. Now that work has slowed down I either have to get the '93 licensed or finish remodeling the master bathroom. I chose the Jimmy. :) I took it over to my friends at Graham Auto Repair and they checked fuel trim and a few other things and apparently it was getting too much fuel. They checked the O2 sensor and it wasn't functioning properly. I had them pop in a new O2 sensor and now the fuel trims are normal.

I'll take it for another test in the morning and hopefully get the license for it for another year. Then I'll have to replace all the transfer case seals and take care of some of the other issues.

Anything to keep me away from working on the master bathroom. ;)

Update 2: I took the Jimmy for a retest and it failed again with almost identical numbers. Since I had the waiver signed by the mechanic I just got the test waived and licensed it for another year. I'll worry about whether or not it's running rich later.