Emissions Failure NOX

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skyehunter

skyehunter

10 Year 15 Year
Joined
May 29, 2009
Threads
18
Messages
161
Location
Arizona
Website
www.jamiebrooks.com
1989 X-Cab 4X4
118K Miles
31" x 10.5 Tires
3.0 V6 Engine

I have failed Arizona emissions twice and have done the following repairs antd tests in attempts to pass. I am looking for suggestions.

Recent Maintenance: Plugs, wires, rotor, cap, airfilter, replaced all vacuum lines and confirmed open, adjusted timing due to vacuum leaks from faulty bimetal valve.

Tested due to failure: VSV valve= failed and replaced. Bimetal valve broken = replaced as well. Found middle vacuum line into throttle body plugged = unplugged blockage. EGR modulator replaced. Thermostat replaced. TPS = failed to have continuity with .020" feeler gauge = have not addressed issue. EGR = pass with vacuum applied.

Notes: Truck always runs rich, can smell it clearly, plugs mostly clean with light flaky tan colored tip. Idle does not change when jumper used to set base timing. Catalytic converter replaced with 4cylinder passenger car unit after theft, has not been smogged since cat replaced. Engine temp sensor indicates temps to be at about 1/4 of the way up the dial (is this the normal location, 75' outside?).

++++Possible solutions brought to my attention:

-Engine running low temp(changed thermostat, no change), causing EGR not to turn on by VSV?
-Bad o2 Sensor causing truck to run rich?
-Faulty Cat?
-Electrical issue going to the VSV?

Any other suggestions would be great. I am not sure how to test O2 sensor, CAT, or where VSV wires terminate into Computer for continuity test?
 
NOX is reduced by the EGR and the CAT. I would test the EGR valve and the modulator. Was the CAT new or a boneyard unit?
 
I replaced the modulator due to it being bad on the first emission test and the new one works after a test. The EGR appears to work, when a vacuum is applied per the test it supresses the engine. A mechanic said he believed it was not being activated due to engine temp????? Thus I changed the thermostat and no noticable temp differances and still unknown if EGR is turning on.

I do not know where or what the CAT came from. When I bought the truck the previous owner said he had a used CAT from a small 4 cylinder car put on it when the original was stolen. He implied that he thought it was bad when I bought the truck, but did not say why he thought that.

I should have noted when I did my initial tune up after the first fail I found a vacuum leak in the bimetal valve the NOX dropped from 8.0 to 7.0. The requirements to pass appear to be 4.5.

I have read all the emissions post I could find on the site and applied those possible issues where I thought they apply to this year and type of vehicle. Seem to be stumped and would like to find solution with the least amount of unecessary parts replacement. lol...

Could the CAT cause the truck to smell rich???
 
My 94 V6 4Runner had a bad o-ring seal and the check engine light would come on... I forgot the code but overfueling was listed in the stuff the check...

Anyway, it's my understanding that a check engine light (in Nashville anyways) is an insta-fail...

TWICE I stopped about 500ft from the emissions place and pulled the negative cable and waited a minute...

TWICE it passed... It took way longer for it to trip the light than the time I took sitting there.

I have no idea if this will help anybody... But I think it's certainly worth a try.
 
A few suggestions actually since we just finally got Lil'Bro's working.
(*Wristy thanks for taking the somewhat redundant calls tonight.)

skyehunter said:
Found middle vacuum line into throttle body plugged = unplugged blockage.
Click to expand...

LMFAO..at least we're not the only one's with this issue this week..

Test the primary O2 sensor if you have one forward and one aft of the cat. The secondary is for mapping mostly as I understand it all.

Pull off the plastic cap from the EGR and make sure it's all clean under the little white filter. Also check your vac tubes that go under the plenum, we found one clogged w/ rust b/c of moisture, easily fixed w/ a piece of piano wire.

Also, for some reason on this specific 3.0 engine it actually ran much cleaner at only 0-2degrees versus the 8-10. I don't know why and after all the crap we have messed with it's working good and not even tripping the CEL anymore.
 
That'a boy.
 
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