Failed CA Smog - High C0

'90 XJ w/ ~180,000 miles. Brand New TPS adjusted to exactly .830. Plugs, Distributor, Dist Cap & Rotor, Wires all replaced no more than 7,000 miles ago. New air filter the day before the test. I do have pretty bad blow by which I am having trouble tracking down since I have good vacuum (and a new grommet) at the back of the valve cover - yet no suckage at the front valve cover tube.

Smog Results


The mechanic beleived these numbers are due to running too rich. After some research here, I would agree. Now, let discuss where things might be going bad for me... My research has revealed the following likely candidates and places to look:

1. Bad Cat - Its likely wasted one way or another due to the rich running condition for the last year.
2. Leaky exhaust manifold - which can cause the 02 sensor to falsly report a lean condition thereby compensating with a richer mix
3. EGR - stuck open?
4. Too much carbon buildup - I dont know how this affects emissions but it has been mentioned in several other posts.
5. Air charge temp sensor
6. o2 sensor?????

What am I missing and suggestions on where to start?

-justin

Id start by seafoaming the engine changing tho O2 sensor and checking the wire/s for bad connections then id drive for a day or two then look at checking the rest of your list starting with the EGR

My old eagle talon was always on the line for emissions. Due to a tuning error from experimenting before I knew anything about tuning, my engine ran way too rich which I think did the same thing to the cat as you are describing. In my case I had to get the engine very hot to pass the test. I don't mean leaning it out, I mean I had to drive it pretty hard right before the test, then get it tested immeaditly without letting it sit for a while. Otherwise I was over the line. Good luck.

Dirty Fuel Injectors can contribute to rich running.

The O2 sensor just reads the O2 in the exhaust, not the other emissions. So, if something is causing fuel not to burn completely, there would be extra O2 with the unburnt fuel. The O2 sensor would just read the extra O2 and think you need more fuel and richen up the mixture. Fuel NOT burning completely would cause extra CO as well, even if the A/F ratio is dead on.

Vacuum leaks is another problem, it could cause your problem as well, so do some investigation for vacuum leaks.

Carbon Deposits, dirty injectors that do NOT fully atomize the fuel, blow by gas's and oil in the combustion chamber could all contribute to incomplete combustion.

As well, a big build up of "CARBON" deposits, what is CO? Carbon and Oxygen combined, the extra carbon in the combustion chamber can create CO as it burns in the combustion chamber.

Blow-by caused by a bad CCV system, there is an orifice mounted in the valve cover attached to the vacuum tube going to the intake manifold. Make sure the tube is good, no vacuum leaks and the orifice is clean and open fully. Run a pipe cleaner thru it. Thats all it took to stop my CCV system from puking oil everwhere and all over the air filter.

The CAT should combine the CO and HC and extra O2 into CO2 and H2O, so if it was bad, you'd get extra CO.

I'd do the little cheap things first, the Combustion Chamber Cleaner, the fuel injector cleaner that also cleans off deposits on the valves and pistons, etc. Lucas and Chevron are generally regarded as somewhat effective, the others NOT so effective.

Look for exhaust leaks, but for an exhaust leak to really effect the O2 sensor it has to be pretty big, you'd hear the leak if it was effecting the O2 sensor.

Remove and clean up your EGR, if equipped, see if you can find any reference to test it for proper function.

Can you check codes from your PCM with the Key On-Off-On-Off-On method? I'd correct any code you get from there as well.

Look up in the manuals how to test your sensors and test the sensor you listed and see if you find any that are bad.

If you can afford it, replace the O2 sensor, even if it wasn't the cause, it can help get better mileage and smoother running. I've heard they can be off and not throw a code in the PCM.

When all else fails, then I'd go spend the $100+ for a new CAT and go thru the pain of R&R that out of the exhaust.

Thanks guys (especially Rick) for pointing me in the right direction.

Anyone else (calling 5-90 ) have advice on the topic given my numbers??

-Justin

A can of BG44k in the gas to clean the injectors and a new O2 will most likely fix you right up. Grab a copy of the Renix fuel injection manual. It will give you the readings to measure with a voltmeter to check out the MAP and Air Charge Temp sensor. Those are the most likely other than the O2. O2's tend to last about 80-150k then crap out. A new O2 will normally help your mileage a lot as well.

Vacuum leak will cause it to run too lean, not too rich.

PS, make sure your ping sensor is hooked up. A bad ping sensor will retard the timing way too much and make the problem worse.

are those the oe injectors? you could almost guarantee that they're leaking internally(if not externally too) @ 180K, might want to replace those and seafoam it too while you're at it.

Ten High said:

are those the oe injectors? you could almost guarantee that they're leaking internally(if not externally too) @ 180K, might want to replace those and seafoam it too while you're at it.

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Although I dont know for sure, I would be inclined to think they are OE.

They are NOT leaking externally. Is there any way to tell if they are leaking internally?

Bump - looking for anyone else's advice before I start working my way down my list.

Anyone else?

what was your nox numbers?

high hc - misfire or inconpleate burning of fuel caused by
1 ignition system fault
2 lean misfire
3 to low of engine temperature, the thermostate

high co - rich condition caused by
1 clogged air filter or pcv
2 bad fuel pressure regulator or bad injectors

high hc and co2- excessively rich condition caused by
1 same stuff as too much co
2 bad spark plugs (misfire)
3 bad cat

since i assume you like to play in rocks, i bet your cat is smashed

p.s, i love the wheels!

edit, if you want to drive down to hayward i can throw your jeep on the smog machine/ dyno/ scope for you

edit again, i looked it up in my fuel induction and emissions book, your hc and co numbers are what they should be pre-cat, so my money is on that it is the cat

buzzbombxj said:

what was your nox numbers?

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That table is an exact copy of what they gave me. Any reason why they didn't measure NOx? Do they not measure it for areas that only require a 'basic' smog check?

buzzbombxj said:

high hc and co2- excessively rich condition caused by
1 same stuff as too much co
2 bad spark plugs (misfire)
3 bad cat

Click to expand...

What is considered 'high co2'?

buzzbombxj said:

p.s, i love the wheels!

Click to expand...

Glad i could hook you up

buzzbombxj said:

edit, if you want to drive down to hayward i can throw your jeep on the smog machine/ dyno/ scope for you

Click to expand...

There is a small chance I might be heading down that way - do you work on the weekends?

buzzbombxj said:

edit again, i looked it up in my fuel induction and emissions book, your hc and co numbers are what they should be pre-cat, so my money is on that it is the cat

Click to expand...

Great info... CAT will definatly be replaced.

Thanks,
Justin

HTeK said:

That table is an exact copy of what they gave me. Any reason why they didn't measure NOx? Do they not measure it for areas that only require a 'basic' smog check?

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I havent taken the smog class yet, just used the emissions analizer, and i was under the impression that nox was one of the gasses california tested for. My powertrain and emissions book is at home or i would look it up. If they didnt test for it, cool.

HTeK said:

What is considered 'high co2'?

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Thats a typo, it was supposed to say co

HTeK said:

There is a small chance I might be heading down that way - do you work on the weekends??

Click to expand...

All the cool equipment i get to use is at my school, i have that class monday through thursday, 8-11:30, if you wanted to come down on a weekday morning we could probobly run it, but i bet its the cat, good luck!

keith

I PASSED!!!!!!!!

Just took it in and passed with flying colors - below the average in all categories.

I didn't find a definitive source of the problem, but what I did sure worked. My suspicions are that it was either a junked out CCV system or a bad CAT.

For future reference, this is what I did:

1. Oil change with SeaFoam. Drove it a few hundred miles and changed it again the night before I smogged.
   
2. Seafoam through the intake
   
3. Can of seafoam + tank of gas to clean anything else up (Note: I didn't smog with any seafoam in the tank)
   
4. Compression Test to determine if my massive blowby was caused by bad rings. My numbers were 150, 132, 132, 150, 150, 150 - I was shocked by this since my motor is about 180K and I thought that perhaps it wasnt very well taken care of.
   
5. Since compression test was good, I had to determine why I was getting so much blowby. Pulled the valve cover and cleaned it up spotless. replaced all three different "parts" that make up the CCV vaccuam system. It is no longer blowing gasses into the airbox at idle.
   
6. New CAT. It may have been all that was needed to fix my problem, although the waffle appeared to be in good shape when I pulled it.
   
7. New O2 Sensor just for good measure.
   
8. New spark plugs
   
9. New Cap and Rotor
   
10. Fuel pressure test to confirm I wasn't feeding it too much fuel. My numbers were right on the money @31 and 39
    
11. Coolant Temp Sensor check - seemed to be within spec
    
12. Manifold Air Temp Sensor check - seemed to be within spec
    
13. Cleaned the EGR valve. It didn't look like it was stuck open, but who knows.
    

A big thanks to everyone who pointed me in the right direction!!

-JM