BrittonHoward

I have a 1989 Jeep Cherokee, 6c, 4x4, auto trans. I live in Las Vegas, Nevada (so no california emission standards)

My jeep will not pass smog and the latest failed results from the smog check are:

High speed co 1.63% - greater than 1.20
Idle speed hc 302 - greater than 220 parts per million

What I have done so far to get to this point (the results previously were allot worse):

Changed oil, oil filter, spark plugs, spark plug wires, air filter (so a good tune up).
I swapped out the catalytic converter from a parts jeep, and my oxygen sensor when looked at is white.

It had been suggested took me to look at my O2 sensor, EGR valve, and my fuel injectors. After looking at the fuel injectors they seam to be only a couple of years old and I know nothing about the EGR valve.

I am on a tight budget restraint, as we all are, and I could use some help to figure out what is the right way to go to get my jeep to pass smog. I do all off my own work with some friends.

Any suggestions? Cause I'm getting quite frustrated...

Britton

5-90

What are the rest of the results? All are informative...

Elevated HC and CO typically results from a rich mix - HC is unburned fuel, CO is partially-burned fuel. Potential causes:
- Failed/failing HEGO sensor (the ECU will swing to slightly rich of the HEGO signal loses validity.)
- EGR valve stuck open (depresses combustion temperatures, reducing combustion efficiency)
- Failed/failing catalytic converter (the EGR is there to reduce NOx, but does so at the expense of increased HC and CO. The cat is supposed to take care of that.)

But, the same thing I say to everyone else that posts with "I failed emissions testing" - givvus all of the numbers, including "Pass" results! That will help narrow down the potential failure much more readily...

CO - Carbon Monoxide Emissions. Partially-burned fuel (the "ash" from combustion of a hydrocarbon is carbon dioxide and water vapour. But, gasoline isn't a "pure" hydrocarbon - USEPA and CalEPA keep playing with the formulation for no particular reason.)
ECU - Engine/Electronic Control Unit. The "computer" or "brain" that makes all of the engine's decisions.
EGR - Exhaust Gas Recirculation
HC - Hydrocarbon Emissions. Unburned Fuel
HEGO - Heated Exhaust Gas Oxygen (sensor.) This monitors the fuel mix after combustion, providing a closed feedback loop.

BrittonHoward

Unfortunately pass results are not provided...only fail results are provided. Thank you for the assistance.

Bustedback

Did they give you a print out of the results were for HC, CO, CO2, and NOX?

BrittonHoward

High speed co 1.63% -greater than 1.20
Idle speed hc 302 -greater than 220 parts per million

Is really all that it says..

BrittonHoward

Here is the link of the picture of the results provided...

http://www.facebook.com/photo.php?pi...&id=1660494480

5-90

Great - that pic confirms what you said before.

Did they give you the passing numbers as well? I know the CA smog report will give you all numbers, and getting all numbers is more instructive than just getting the "Fail" results. There's a reason I ask for them - they may help us tell you where to look first, so you don't shotgun parts at the thing and end up spending far more than you need to...

BrittonHoward

The only part of the 21st results that were cut off on the pic was the testing facilities information/credentials

mlyon83

I passed smog with Seafoam.

1st use of Seafoam (1 can):

Public Servant: "You almost passed."
Me: "K, brb."

7 days later....

2nd use of Seafoam (1 can):

Public Servant: "I'm suprised, but you passed."
Me: "K, thanks."

Works miracles.

5-90

Then all I can give you is the general advice you already have from my first post. I don't have enough information to "fine-tune" it, so you're going to have to do some testing & digging...

BrittonHoward

Thank you for your help... Based on what you said and what I know it looks like me putting in a new cat converter tomorrow is the best choice to go do.

Bustedback

When was the last time the oil was changed? Having clean oil in the crankcase will help a little, but every little bit helps.

BrittonHoward

Yep, that was done.