Failed Emission - Please help with troubleshooting

[asaracho]

Hello, all! I just purchased a 1992 FJ80 with 153,000 miles and am having issues with it passing the emission test. This is a great forum and hope to be able to contribute useful information in the future. Here's my problem:

I went in to do the emission test here in the beautiful state of Colorado and failed. Seems I am running abnormally rich. I did notice some black soot in the tail pipe and averaged 14mpg on a 800 mile highway drive travelling at an average of 65-70 mph. Thought that was about normal, though.. Is it not?

The only things i've done to the cruiser is replace the airfilter and change the oil. The car passed emissions in Missouri in '07 (at least that's when it was last registered) and failed today here in Colorado. I get to retest free of charge if I take it back within 10 calendar days. So, without further ado, here's what the inspection report says:

Basically, everything passed except high HC (hydrocarbons), and very high CO readings.

HC limits are 2.50 and I scored 3.1720
CO Limits are 25.0, I scored 155.4853!!

The inspection sheet mentions that high HC readings are a result of unburned fuel or partially burned fuel. And that high CO readings come from the Air/Fuel Mixture being too rich.

I have not had a look at the spark plugs yet but I plan on replacing them before I go back in. I'm also running fuel injector cleaner through a couple of tanks (any recommendations here?) I've used xylol before on other vehicles and it seems to work, as well as seafoam.

Anyway, any help getting this fixed will be greatly appreciated!!

Thanks,
Alfredo

 

[asaracho]

Let me add that the cruiser idles at around 750 rpms and is smooth throughout accelerations, no stumbling or misses and no check engine lights as well.

 

[hntashdjian]

I would change O2 sensors & spark plugs at the minimum.

 

[94SRUNNER]

I would begin with a search and look at the FAQ section.

Then you may want perform some base-lining, (i.e. OEM spark plugs, OEM wires, etc)

Do you have CEL (Check Engine Light) on? Ifs check the codes. You may also want go ahead and replace the O2 sensors.

 

[trapper92]

was the truck at normal operating temp went you took it through the test? if it wasn't it would certainly be running rich.......It's best to take the truck for a good run to get the cats nice and hot prior to testing also.

speaking of...you never mentioned how many miles are on your truck and the condition of the catalytic converters....you can use a temp sensor to test to see that your cats are operational, the exhaust coming out of the cat should be about a 100 degrees hotter than the exhaust entering the cat. this tells you that the cats are burning all the unburned fuel.

I would propably check your O2 sensors prior to just replacing them, 14 mpg and the fact the truck is running well says to me that they might be just fine.....

hope this helps a little....

 

[asaracho]

Thanks for the suggestions, guys... I did forget to mention that the cruiser just turned over 153,000 miles - not very many compared to some that i've seen!

The truck was at normal temp when i got there then it sat for 30 minutes before they did any testing. They got it up on the dyno and had to retest because the first guy didn't get it up to speed fast enough on the 60mph portion of the test. So I'm assuming that the engine was fairly warm when they tested it. I'll be sure to check the catalytic converter is doing it's job, thanks for that suggestion!

 

[landtank]

I'm thinking

O2 sensor causing rich mixture
air pump not injecting air into exhaust
cat not burning un burned fuel

good luck with this one

 

[Eric Winkworth]

I have had a good amount of experience with this, and as a rule of thumb... It's always good to do the cheap tune up parts first... O/2, new plugs, cap and rotor, wires and look at any EGR and PCV valves and make sure they are functioning properly... Also a good idea to check timing (although if you've never messed with it, it shouldn't be the issue)

All that being said once you're done, get it tested again if you fail, it's a very very good chance that you need a CAT...

Now from what I've learned over the last few years in personal experience and talking with friends... If you put a new CAT on a really s***ty running engine, do a fresh oil change and fresh gas... get it up to normal operating temps for the test and run it... it almost always will pass!

Now I realize cats are the most expensive emissions control device on cars/trucks these days.... So I always recommend doing it last... Here in ontario it's pretty much a money grab, 100 bucks to diagnose the issue (which doesn't even give you a garentee that it will pass after you replace) I figure 100 bucks can at least do plugs and wires...

just my 2 cents
good luck! I know it can be frustrating!

Also always take your truck for a good highway run, and flog it a bit... the first fail I got was I think mainly from not getting my cat hot enough, even though most emission test facilitys will tell you they put it through a warm up, it's BS... Warm it up good yourself!

 

[asaracho]

Hey, Eric! Thanks for the thorough response. I will replace the cheap tune up parts first, just like you said, and report back next week after I do the re-test. I'll make sure the cat is nice and hot too.

Thanks alot guys!

 

[94SRUNNER]

Just don't use cheap parts, go with quality!

Good luck and keep us posted. Its always nice to see when someone solves there Cruiser problems.

 

[lt1fire]

It also could be that your valves need some adjusting.

 

[Eric Winkworth]

Just like when you read the fail pamphlet they give you, it "COULD" be alot of things... When I initially had my E test issues... I had people telling me some older engines will never pass, to saying I may need head work, honestly it's all BS... If your truck is ticking like a time bomb and low on compression sure you could potentially need valve adjustment or machine work done on your head... But realistically an engine that is running smooth and idling at the proper RPM should have no trouble passing unless you need a CAT... (or maybe certain tune up parts)

I think a fresh oil change is a good idea too!

cheers
Eric

 

[Skrewball]

so they ran the truck on a dyno??

you should have gotten a NOx reading as well. if so what was it??

i am leaning towards the CAT being the issue.

with a high HC reading, an oil change always helps.

start with the basics filters, timing, plugs,

 

[trapper92]

with a high HC reading, an oil change always helps.

really.....an oil change?

you are the 3rd guy to say this, but I don't get how this would change his emission #'s.
certainly nothing wrong with baselining the truck though.



.

 

[jonheld]

https://forum.ih8mud.com/80-series-tech/173701-nj-smog-test-results.html