I failed emissions... oh noes!

1991 trooper v6/auto

The lame sauce is that when I bought the truck in California 2 months ago, it ran like poop but passed California emissions. I took it home, fixed several problems... and now it failed.

Here's what I've done so far that might affect emissions:

• New injectors
• Repaired multiple vacuum leaks (with a hand gauge and careful tracing I am not able to find any further vacuum leaks... Seems tight now on the vacuum front)
• Re-connected the vacuum line to the A.I.R. pump diaphragm & confirmed operation
• new plugs & wires
• new o2 sensor
  

Yes, I reset the computer to the best of my knowledge and drove several days after all repairs and prior to having it emissions tested.

One thing of note, the vehicle has a bit of hesitation when accelerating from idle. I'd like to fix that in any case

Here is the emissions report from MVD -
http://65.82.88.69/azdrvtce/rdPage....=165854&rdRequestForwarding=Form

basically off-the-charts CO during hard acceleration (they practically WOT it) and excessive HC under heavy acceleration.

Any thoughts on where I should start?

Thanks!

How old is your O2 sensor? That's something cheap to do, it's a regular-old GM-type single-wire sensor readily available at any auto parts store and (very cheap) on eBay. Access from the driver's side to replace the sensor; it's just forward of the cat, sticking straight up.

And I'm thinkin' that if you've got lots of miles and still on the original catalytic converter, it's probably hashed and could use replacement. A Most Excellent time to upgrade to 2-1/4" exhaust and cat!

There are emissions-enhancing additives you can put in your gas which might help. Or perhaps a nice load of Gasohol which should lean things out a bit!

You can check engine timing to make sure it's in spec. You have to disconnect the ESC (Electronic Spark Control) wire in the center console from itself prior to attempting to check timing, or you won't get an accurate reading. It's the only single wire in the console with an inline connector.

Regarding the poor driveability, you might try resetting your idle speed/IAC, and TPS voltage.

http://www.s-series.org/htm/how2/tpsadjust.htm

http://www.4x4wire.com/forums/showflat.php?Cat=&Number=445449

A new cap & rotor might also be in order if it's been a while.

Anyway, that's a start, if you don't find a solution post back with more info.

HTH...........ed

P.S. don't know if the "HP" listed in the emissions report is a code or not, but a stock 2.8 certainly doesn't have 213 HP!!!!! <img src="/forums/images/graemlins/lol.gif" alt="" /> More like 125!

You're NOx readings appear to be within spec, so your EGR system is probably working.

Your HC and CO readings are what is too high.

Likely a catalytic converter gone bad.