I bought a 94 FZJ80 in December and I've taken and failed 3 emissions tests in Colorado due to high NOx. I think I've narrowed it down to a faulty VSV, but I would appreciate some input before I spend the $$$. I've attached the charts from the 3 tests.
I took my truck in to test in mid-morning, and took mostly surface streets for about 6 miles to get there. I sat in line for 30 minutes with the truck idling before I tested, so everything was relatively cool in temp.
Test 1 Results in GPM: (reading/limit)
HC: .44/2.0
CO: 4.19/20.0
CO2: 326.18
NOx: 5.06/4.0
After I failed the first time, I did the following (some related to emissions, some not): cleaned IAC, cleaned PCV, intake cleaner in PCV port, cleaned EGR modulator filter, removed and cleaned EGR valve & temp sensor and reinstalled with new gaskets, replaced K&M air filter with new OEM air filter.
Following the advice of some on this forum, I got the engine/cats running super hot before I tested. I was only waiting in line for about 5 minutes. Inflated tires to 40 PSI.
Test 2 Results:
HC: .69/2.0
CO: 10.08/20.0
CO2: 671.39
NOx: 13.15/4
NOx readings almost tripled??? Since getting things super hot sent me the wrong way, I drove my truck easy on the way to the third test, and sat in line with the truck turned off for about 20 minutes while waiting in line. I also put 1/2 tank of premium with a red bottle of HEET. Replaced K&M air filter with new OEM air filter a week or so before the test.
Test 3 Results:
HC: .80/2.0
CO: 10.13/20.0
CO2: 721.22
NOx: 14.27/4
After my most recent fail, I figured that I'm missing something. Today, I decided to check the VSV to make sure it's working properly. I followed this and this thread in order to not have to remove the intake chamber as called for by the FSM. Otherwise, I followed the FSM.
I measured 32 ohms between the bottom 2 terminals on the left side, so all good there.
I disconnected the vacuum hoses leading in/put of the VSV and was able to blow through it, although it wasn't "easy." I then applied 12V to the bottom 2 terminals on the left side and was still able to blow through with the same resistance. I also didn't hear a click when giving it power, but I've read that it isn't always audible. FSM says to replace the VSV if this happens.
Thus, I think I need to replace the VSV. But before I buy it and replace, I want to make sure I'm not missing anything. Here is what's been puzzling me:
I took my truck in to test in mid-morning, and took mostly surface streets for about 6 miles to get there. I sat in line for 30 minutes with the truck idling before I tested, so everything was relatively cool in temp.
Test 1 Results in GPM: (reading/limit)
HC: .44/2.0
CO: 4.19/20.0
CO2: 326.18
NOx: 5.06/4.0
After I failed the first time, I did the following (some related to emissions, some not): cleaned IAC, cleaned PCV, intake cleaner in PCV port, cleaned EGR modulator filter, removed and cleaned EGR valve & temp sensor and reinstalled with new gaskets, replaced K&M air filter with new OEM air filter.
Following the advice of some on this forum, I got the engine/cats running super hot before I tested. I was only waiting in line for about 5 minutes. Inflated tires to 40 PSI.
Test 2 Results:
HC: .69/2.0
CO: 10.08/20.0
CO2: 671.39
NOx: 13.15/4
NOx readings almost tripled??? Since getting things super hot sent me the wrong way, I drove my truck easy on the way to the third test, and sat in line with the truck turned off for about 20 minutes while waiting in line. I also put 1/2 tank of premium with a red bottle of HEET. Replaced K&M air filter with new OEM air filter a week or so before the test.
Test 3 Results:
HC: .80/2.0
CO: 10.13/20.0
CO2: 721.22
NOx: 14.27/4
After my most recent fail, I figured that I'm missing something. Today, I decided to check the VSV to make sure it's working properly. I followed this and this thread in order to not have to remove the intake chamber as called for by the FSM. Otherwise, I followed the FSM.
I measured 32 ohms between the bottom 2 terminals on the left side, so all good there.
I disconnected the vacuum hoses leading in/put of the VSV and was able to blow through it, although it wasn't "easy." I then applied 12V to the bottom 2 terminals on the left side and was still able to blow through with the same resistance. I also didn't hear a click when giving it power, but I've read that it isn't always audible. FSM says to replace the VSV if this happens.
Thus, I think I need to replace the VSV. But before I buy it and replace, I want to make sure I'm not missing anything. Here is what's been puzzling me:
- While I am reasonably competent in working on cars, it's entirely possible that I am screwing up checking the VSV.
- I think it's weird that my NOx readings almost tripled from my first test. This makes me think I messed something up when I did the work after Test 1. I don't have a vacuum pump so I've never tested the EGR valve. Is a bad EGR valve a possible culprit? In my head, it would be a huge coincidence if the VSV went bad in the 8 days between my first and second test.
- I've read that the VSV can fail intermittently. It's possible that it was fine for the first test but not for the next 2?
- I've never had a CEL. Since it's an ODBI, I used the paper clip method and didn't get any codes. Shouldn't I get a CEL if the VSV isn't working properly? Or possibly is the ODBI incapable of sending a code for a bad VSV?
- I don't notice any issues when I drive it. I've only had it since December, but I pay very close attention to my trucks driving behavior/sounds/etc and I think I would have noticed it if my truck was running funky.
- The cats look like they could be replaced, but obviously looks aren't dispositive. If I needed new cats, I would expect my other readings to be high as well? PO replaced the O2 sensors within the year.
- My truck passed California emissions tests, but it doesn't appear that they test for NOx (I have 2 test results from PO). So I don't know how long this has been a problem for.
