Failed Colorado Emissions - NOx - FJ80 1994
- Thread starter ColoradoCruzer
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The simplified version is.... At certain temps, once the vehicle is warmed up, the addition of exhaust gas into the intake helps to reduce nox. Which is why most people are telling you to look at the exhaust gas recirculation (egr) system.
If you're running rich or lean, seafoam can help, denatured alcohol can help etc. Unlikely to help with nox.
Assuming you have a 1fzfe motor, I would buy a throttle body gasket from stevinson, take off the throttle body and clean passages for the egr system into the intake.
Colorado cruiser, just in case the EGR doesn't fix your problem, there are a few other possible causes for an elevated NOx reading. The mixture being slightly less then 10% lean can cause elevated NOx levels, or an increased idle speed over the stock setting can cause elevated NOx readings too. If it's been many years, and miles since your O2 sensors were last changed, or in some cases they may have never been changed, you might want to think about replacing them. Changing the O2 sensors will help send accurate mixture data to the ECM
- Thread starter
- #24
Rifleman: That is interesting you say that. I had my ECT on during the dyno test at the dmv. I wonder if that caused the nox reading to be a little higher.
IF you go the Sea-foam route, make sure it's all burned out of your fuel system BEFORE you go in for another test. I seafoamed mine and took it in for a test on the same tank and failed in the most spectacular fashion. Once I ran the rest of that tank through and filled up again my readings were back to where they were (still failing for NOX). In fact my truck is STILL failing for NoX despite me throwing a lot of time and parts at it. I think IU am finally on the right track with the VSV's to get the EGR working again. I'll post up if I ever get it passed.
Occam's razor.
My '94 was improved but still a little temperamental with NOx even after new O2 sensors and an EGR system cleaning. High NOx indicates a high combustion temperature. A high combustion temperature can be caused by a lean fuel mixture. Therefore O2 sensors and fuel injectors are possible suspects after ruling out the easier items.
Your catalytic converter also reduces NOx by breaking it down in a chemical reaction which requires high temperature, so high NOx can indicate a failing catalytic converter.
Here's what worked for me, same day after failing an emissions test for high NOx: 20 minute lap on the highway to get the Cats good and warm. While I waited in line I revved the engine to keep them warm, which may or may not have helped. I turned PWR "off" (no overdrive) and ECT "on" (higher shift points). Same tank of gas, and passed the re-test same day.
It's a shame that Colorado has higher emissions standard for Cruisers than when they were new
Your catalytic converter also reduces NOx by breaking it down in a chemical reaction which requires high temperature, so high NOx can indicate a failing catalytic converter.
Here's what worked for me, same day after failing an emissions test for high NOx: 20 minute lap on the highway to get the Cats good and warm. While I waited in line I revved the engine to keep them warm, which may or may not have helped. I turned PWR "off" (no overdrive) and ECT "on" (higher shift points). Same tank of gas, and passed the re-test same day.
It's a shame that Colorado has higher emissions standard for Cruisers than when they were new
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- Thread starter
- #28
Kungpaodog:
Wait do you mean you turned ECT on and Overdrive off?
My '94 was improved but still a little temperamental with NOx even after new O2 sensors and an EGR system cleaning. High NOx indicates a high combustion temperature. A high combustion temperature can be caused by a lean fuel mixture. Therefore O2 sensors and fuel injectors are possible suspects after ruling out the easier items.
Your catalytic converter also reduces NOx by breaking it down in a chemical reaction which requires high temperature, so high NOx can indicate a failing catalytic converter.
Here's what worked for me, same day after failing an emissions test for high NOx: 20 minute lap on the highway to get the Cats good and warm. While I waited in line I revved the engine to keep them warm, which may or may not have helped. I turned ECT "off" (no overdrive) and PWR "on" (higher shift points). Same tank of gas, and passed the re-test same day.
It's a shame that Colorado has higher emissions standard for Cruisers than when they were new
Wait do you mean you turned ECT on and Overdrive off?
One more small tip to get you over the hump, the more air pressure in your tires = less rolling resistance on the rollers.
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- #30
What does rolling resistance have to do with a dyno emissions test?
Sorry for the long link... Is this what your talking about ?
Document Display | NEPIS | US EPA
Sorry for the long link... Is this what your talking about ?
Document Display | NEPIS | US EPA
They drive your car on rollers up to a designated speed. More air in the tires mean the tires don't deform around the rollers as much, thus requiring less effort from your drove train to achieve the designated speed.
The tech won't have to push on your accelerator as hard to get your rig up to speed, which means your rig uses less fuel and emits less NOX.
The tech won't have to push on your accelerator as hard to get your rig up to speed, which means your rig uses less fuel and emits less NOX.
- Thread starter
- #32
so the fact that i put on brand new bf goodrich ta ko2's tires 285 75 16 does or dosent help my cause
Anything that reduces your fuel economy will increase your emissions. But there are plenty of us getting through Colorado emissions with 315's and larger.
Yes, thanks. I edited my post.
What happens in CO if you install an LS?
They'll go off of the year of the LS. Would still largely need to at least appear to have original factory emissions equipment. As for plugging into the ECU - I haven't done it in an OBDII car yet but my swapped + standalone car they don't even try to connect to.
Robbie @ Adventure Off Road is another local resource, but also potentially busy.
Also, I keep the 'pwr' or 'ect' button on as if I don't, it fails due to not being able to get up to speed in the allotted time even with 4.88s. Having earlier shift points would help with using a little less throttle.
Just be glad it isn't stick shift. I'm registering my manual cars out of town because I'm tired of hearing gears get ground, and vehicles lurch around all over the rollers. I watched them kill a subaru wagon last time I was there and just shrug their shoulders. Good luck.
Robbie @ Adventure Off Road is another local resource, but also potentially busy.
Also, I keep the 'pwr' or 'ect' button on as if I don't, it fails due to not being able to get up to speed in the allotted time even with 4.88s. Having earlier shift points would help with using a little less throttle.
Just be glad it isn't stick shift. I'm registering my manual cars out of town because I'm tired of hearing gears get ground, and vehicles lurch around all over the rollers. I watched them kill a subaru wagon last time I was there and just shrug their shoulders. Good luck.
New LS has no egr...
If it didn't have it from the factory, then you're good to go. Also 50/50 odds they have no idea what they are looking at.
Edit: if you're talking about a crate motor, I'm not too sure how that one would work.
Edit: if you're talking about a crate motor, I'm not too sure how that one would work.
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you can look in mitchell and it lists all the emissions control equipment. gen3 vortecs had EGR up to 2004. 2005 and later has no EGR. They will plug into the OBD2 and at least check to see everything is showing as "ready."
I'd like to go erod crate engine. It's cleaner than stock!
