Help me decifer emissions report......

[Ramblin Fever]

Just curious to see if anyone feels that the differences in the last 2 emissions tests on the Rodeo are anything to be concerned of.

Both emissions are of a passing result, but there are values that have changed that I wonder are of age or just the fact that the engine may not have been hot enough during this last emissions test.

The test I'm comparing the new one too, was the one taken 2 yrs ago, with 138k on the clock. Values were:

HC GPM 0.0395
CO GPM 0.7502
CO2 GPM 477.1736
NOx GPM 0.6718

This test, with 170,500 on the clock, revealed:

HC GPM 0.6240
CO GPM 3.9642
CO2 GPM 529.9406
NOx GPM 2.4944


Still well within limits of their maximums:

HC 4.0
CO 20.00
CO2
NOx 9.0

When I went for this last emissions, I had only drove the truck 17 miles at 45mph stop/go after having sat for 5hrs on a 70 degree day; it was in the normal temp zone, but I wouldn't classify 17 miles truly warmed up.

What do you all think?? Something going on here, or just normal age??

Forgot to remind y'all, this was the truck with the EGR issue last year, that I eventually solved by replacing the MAP sensor. After cleaning the EGR a 100 times, and finally replacing the EGR valve itself.

[Gizmo42]

17 miles even of slow speed driving should be plenty to warm it up for testing. Sometimes small things can make a big diffrence in the readings. I usually change the oil, pcv valve, new air filter, and clean spark plugs (when I used standard plugs on my mitsu) the day before or of the test. The only time I didnt do those things my readings were way higher then the previous year, then the next year they were back down again. Dont know if that was the actual reason or maybe thier equipment just wasnt calibrated the same. My mitsu always got a fast pass even after 15 yrs and 143k miles.

[Ramblin Fever]

Well, everything you mentioned was just very recently done.

Just switched back to diesel oil/Rotella synthetic 5w-40 1k miles ago, pcv was cleaned at the time & air filter was changed the same day.

Spark plugs have roughly 19k miles on them or so - NGK's.

[Gizmo42]

Its possible it could be the oil, maybe the extra addatives effecting the readings. Cant think of anything else that would effect all the readings at the same time. Since its not really enough of a change to worry about I guess just wait till next time to see if it changes at all either with the same oil or diffrent.

[Ramblin Fever]

You mean the diesel oil itself could be causing higher readings??