2000 Toyota Tacoma 3.4 V6 failed NOx GPM emission test

Sorry to hear that Josh. A couple years a go, I took a friend car for inspection for her,it failed the NOx, and the inspector told me to get on expressway about 20 minute and then come back for reinspect. The dang thang passed. So I don't know what to tell you, i'm mechanical inclined..

 

I was just reading that a bad EGR valve or bad cat would cause higher NOx readings.

 

I was told that the cat need to be hot... to elimate the NOx...

 

This would be true. A cat that's working properly works by getting supper hot and burning off excessive gasses that aren't burnt by the motor or some gases that are created by the combustion process.

 

NOx and HC run an inverse relationship depending on cylinder pressures.
Check your timing. Running too much advance will reduce HC, but increase NOx.

 

Driving 15-20 miles is enough for that... same as when yours failed.

I had a '91 Escort that failed after driving about 5 miles to the station. Tech told me to get on the freeway and drive for a bit, come back, and it would pass. It did.

 

Does anybody have a passing 2000 toyota tacoma v6 with the specs of what I should be running right now?

 

Standards are going to vary by state.
The pass/fail levels, as well as your current levels, should be on your paperwork.

You most likely have a failing cat, but rather than shotgunning the problem, you need to suck it up and take it to a shop that has the equipment and knowledge to fix it properly.
At 50% above your limit, you are beyond the level of "chemical" and DIY repair.

 

Josh,
I don't know if this would help,but it worth reading it.

 

Could try replacing the egr and I want to check out the o2 sensors but me and exhaust bolts don't get along. Also bout the bank 1 sensor 1 before the cat and 2000 being the split year. Date is 01/00 so I'm assuming it would be the old style connector right.

 

You can spend $5000 replacing parts and not get any improvement.

The EGR valve is a very simple device. They sometimes go bad, but they can also be tested.
Sometimes it's just a piece of soot on the pintle seat keeping it from closing properly and can be cleaned.

 

I don't think the 3.4 even has an EGR (the 2.7 does).

One other cause for excess NOx is the fuel mixture being too lean. This is a shot-in-the-dark, but you could have a bad sensor tricking the ECM into lessening the injection duration. BamaToy1997 might know more about this possibility.

 

Your on the right track with the EGR. Make sure no one has plugged the hoses with some thing or just pulled them off. The purpose of the EGR is to reduce NOX.

 

The EGR as far as i know has never been serviced, looked at, checked, or messed with at all. Could give cleaning it a shot and see. The 3.4 does have an EGR its at the backside of the intake. Any good cleaning method advice on cleaning the EGR? EGR Valve, EGR Vacuum Modulator, VSV for EGR, or all? Also can a charcoal canister be cleaned?

 

Hey 97Blk One your link did help me think of a solution and i think i have it. The part where Reina is saying "to save yourself some money by just changing the front O2 sensor, since the rear one really don't do anything related to engine operation. All the after Cat O2 sensor do is to turn on a MIL light for a P0420, letting you know the Cat is no longer doing its job." If this is true i just checked my O2 sensors and cleaned and the one after the Cat has a bad wire right before it goes into the senser not the wire connector. Could this be the trigger for my problems? Thing is i DONT have a MIL light on but would there be a problem with the light turning on because of the bad wire. I think i'm finally getting somewhere. Thanks for the help everyone.

 

The O2 sensor reads O2 not NOX. It will effect other emissions but have little effect on NOX.

 

Any other things i could try?

 

Replace the cat and the EGR, or take it to a shop that knows what they're doing and won't "shotgun" parts.

 

http://www.tacomaworld.com/forum/1st-gen-tacomas/229674-smog-test-failure-2.html
Here's a link to my thread with very similar issues. I ended up replacing both catalytic converters (california model), fuel filter, both o2 sensors, and thermostat.

 

ya but how often does a shop put everything back where it goes. Heard of some friends cars coming back from shops with missing "important" bolts and other. Whats a good shop to take my truck to around the larimer county colorado area.