4.0 Jeep Emission test results HQ!

I am setting this thread up for everyone to post actual emissions test data results, along with any other pertinent performance or non-oem upgrade data, and details of differences from state to state or county (parish) to county differences in test limits and test styles. This will be for 87-95 4.0 jeeps primarily, as the 96 and new jeeps use the OBD-II system as a pass / fail no tail pipe test method that yilds no data to the best of my knowledge.

Here is my data:

THere seems to be different tests used in Texas, at least here in Harris county.

The 89, 121,000 miles on the odo, recently replaced the head gasket, this one gets exceptional mileage, so far 17-18 in the city mixed, 24 highway reported by PO before the head job, 2 WD had the following results using the "ASM", actual load test, test in Texas, Harris County.

standard @ high speed ...................................low speed
HC (ppm)189...............mine was 123 .................194..............mine 30
CO% 2.36...................mine was .44 ................1.74...............mine .44
CO2 % N/A.................mine was 14.2 .................N/A...............mine 14.2 NOx(ppm)..1233............mine 0.0........................1340............mine 0.0
O2 % N/A...................mine was 0.0 ...............N/A..............mine 0.0
Dilution......<6...............Mine 14.6....................>6..............mine 14.6

Then my 87 4x4 which is not load tested here (they won't run 4X4's on the dyno here for some reason), but it was tail pipe sniff tested using a "2 speed idle test", and this has lower MPGs than the 89 (10-17), about 35% lower, 256,000 on the odo, had:

standard @ high speed ...................................low speed
HC (ppm)220...............mine was 8 .................220..............mine 28
CO% 1.2...................mine was .04 ................1.20...............mine .13
CO2 % N/A.................mine was 14.9 .................N/A...............mine 14.7 NOx(ppm)..1233............mine 0.0........................1340............mine 0.0
O2 % N/A...................mine was 5.1 ...............N/A..............mine 5.4
Dilution......<6...............Mine 14.9....................>6..............mine 14.8

Both passed. Both are OEM, except single platinum (autolight brand spark?) plugs (IIRC). Both run between 190 to 205 F. Both are AW4, with 3.54 rear ends.

1989 XJ, 4.0, AW4, NP231, 4 x 4(so no dyno for me either, just the sniffer) Only performance upgrade is a open element filter setup. The rest is stock as far as emissions are concerned. not sure mileage just redid gears and speedo gear too. 161,589 on the odometer at time of test.

standard @ high speed ...................................low speed
HC (ppm)220...............mine was 10 .................220..............mine 24
CO% 1.20...................mine was .04 ................1.2...............mine .03
CO2 % N/A.................mine was 14 .................N/A...............mine 14.0
O2 % N/A...................mine was 17.1 ...............N/A..............mine 16.4

magimerlin said:

1989 XJ, 4.0, AW4, NP231, 4 x 4(so no dyno for me either, just the sniffer) Only performance upgrade is a open element filter setup. The rest is stock as far as emissions are concerned. not sure mileage just redid gears and speedo gear too. 161,589 on the odometer at time of test.

standard @ high speed ...................................low speed
HC (ppm)220...............mine was 10 .................220..............mine 24
CO% 1.20...................mine was .04 ................1.2...............mine .03
CO2 % N/A.................mine was 14 .................N/A...............mine 14.0
O2 % N/A...................mine was 17.1 ...............N/A..............mine 16.4

Click to expand...

Interesting, your CO is closer to my 87, and my 89 CO was ten times higher, and it has the better mileage, which is real odd. OH, and my 89 has a lot more high speed (over 50 mph) power still than the 87. I have yet to figure that out.

1994 4.0L/Auto 4x4
185,000-ish miles
New Cat, Full tune-up w/ NGK plugs, cap, rotor, wires, fuel filter, Amsoil fuel system cleaner in tank. Fresh Amsoil 10w30 oil change.

15mph - 1675 RPM - PASSED
CO2% Meas. 14.3, O2% Meas. 0.8
HC (PPM)- Max allow = 89, Avg = 19, Meas. = 34
CO (%) - Max = 0.66, Avg = 0.06, Meas. = 0.02
NO (PPM) - Max = 517, Avg = 136, Meas. = 64

25mph - 1896 RPM - PASSED
CO2% Meas. 14.6, O2% Meas. 0.1
HC (PPM) - Max = 54, Avg = 12, Meas. = 23
CO (%) - Max = 0.80, Avg = 0.05, Meas. = 0.01
NO (PPM) - Max = 770, Avg = 124, Meas. = 7

Very happy w/ the results. She is running great!
BTW, New test here since Jan. is that they pressurize the fuel tank to check out the evap system. Mine passed that too......after the tech allowed me to fix a hose that had a crack in it.

jjmat3 said:

1994 4.0L/Auto 4x4
185,000-ish miles
New Cat, Full tune-up w/ NGK plugs, cap, rotor, wires, fuel filter, Amsoil fuel system cleaner in tank. Fresh Amsoil 10w30 oil change.

15mph - 1675 RPM - PASSED
CO2% Meas. 14.3, O2% Meas. 0.8
HC (PPM)- Max allow = 89, Avg = 19, Meas. = 34
CO (%) - Max = 0.66, Avg = 0.06, Meas. = 0.02
NO (PPM) - Max = 517, Avg = 136, Meas. = 64

25mph - 1896 RPM - PASSED
CO2% Meas. 14.6, O2% Meas. 0.1
HC (PPM) - Max = 54, Avg = 12, Meas. = 23
CO (%) - Max = 0.80, Avg = 0.05, Meas. = 0.01
NO (PPM) - Max = 770, Avg = 124, Meas. = 7

Very happy w/ the results. She is running great!
BTW, New test here since Jan. is that they pressurize the fuel tank to check out the evap system. Mine passed that too......after the tech allowed me to fix a hose that had a crack in it.

Click to expand...

So is the avg number a measuered number or the limit? Is the measured number an actual max or actual average?

I can't figure out why the CO limits are so high compared our actual results. Makes me wonder what the CO numbers are with out a Cat.

Thanks posting the data!

Measured numbers are what my XJ tested at. Avg is an average of what previously tested vehicles tested at, Max is max allowable to pass.

Just got back from the emissions inspection on my 89, 4.0, XJ, AW4. Last years results are below. Current mileage is already 137,874, Almost 17,000 miles since last years inspection. Using API SL grade (currently Autozone house brand is the only SL I can find in 10W30) 10W30 oil still. No oil additives. Runs only regular gas, no injector cleaning or Seafoam since the head work(1).

This test was on the Dyno, 2 WD, in Texas, Harris County, Houston.

standard @ high speed (25 mph)...............................low speed (15 mph)
HC (ppm)189...............mine was 35 .................194..............mine 61
CO% 2.36...................mine was .40 ................1.74.............mine .54
CO2 % N/A.................mine was 14.9 ...............N/A..............mine 14.8
NOx(ppm)..1233....mine 420........................1340..................mine 691
O2 % N/A...................mine was 0.0 ...............N/A...............mine 0.1
Dilution......>6...............Mine 15.3....................>6...............mine 15.3

Once again comparing old results below I can make no sense of the O2 readings (if they are real readings?), but this time it showed a number other than zero. HC has dropped 50% on the 25 mph test, CO was nearly unchanged, last year showed zero NOx, which was surprising, but it was a clean rebuilt head, and cleaned manifolds (1), and this time the NOx was way up at about 30 to 50% of the limits.

Also the engine is running about 10 to 20 F cooler now, compared to shortly after the head gasket replacement and head rebuild.

Interesting part of the NOx tests is the inspection tech told me that he has always been able to pass vehicles that failed NOx tests after they used a 2 step injector cleaner and drove 50 miles. The two step is a gas tank additive plus an intake additive (sucked in the vac line like Seafoam). Might explain why the clean head and manifolds in last years test of the 89 showed 0% NOx, right after the rebuild, and now shows 50% of the limits!!!!! Next year I will run Seafoam and injector cleaner a week before the inspection and see what I get.

Seems that carbon build up, and or dirty injectors raises the NOx levels!

Note once again my 87 showed 5.x % O2, the 89 showed no remaining O2, 2 years in a row, and magimerlins below showed 16.4 to 17.1% O2 in his O2 test results (which I doubt unless (2)). So far, the O2 test results make no sense at all. Something must be off on their eq., or printouts. I seriously doubt the remaining O2 is 17% or 0%. But jjmay3's O2 number was between .8 and .1 %.

So the O2 puzzle continues. I guess a high O2 number on a Renix could be caused by an (2) exhaust leak drawing in air, after the O2 sensor, but I suspect that since the O2 has no upper or lower limit for pass/fail, perhaps their equipment is not always working properly on the O2 test, but then why measure it? Maybe it is part of a dilution test.

Anyone else have emissions test data reports to share with a brief engine history?

Ecomike said:

differences from state to state or county (parish) to county differences in test limits and test styles.

Click to expand...

If a locale is determined to be in violation of clean air laws, they are required to engage in emissions testing by the EPA, for that locale. The EPA recognizes two emissions standards, which are the federal standards and the Calif standards. The two have different measurements and requirements. It's up to the state which to use. Note that a state may choose to use strict emissions in one area and none in another (that's how it is here in MD, with some counties having no emissions testing at all, while some others have the stricter Calif package).

History: 1996 XJ, 4.0. Bought it in May of '99 with approx 53,000 miles. Have always used Castrol 10w30 conventional oil (no additives), with a mix of filters (generally Wix/Purolator). Original cat, stock exhaust, replaced both O2s spring of '08, as well as new plugs, wire, cap & rotor. Never had any engine work done. Use BG44K every 6 mos., for the last 5 years or so.

In my part of Colo, I have to do the dyno test (run it up to 55 or so, with tailpipe sniffer) - these are my latest results (Oct of '07), with 170K miles on it (so factory O2s, and cap/rotor/wires/plugs were approx 3 yrs old, not a fresh oil change but within 3K of test).

Readings Limits Results
HC (GPM) - 0.9192 4.0000 Pass
CO (GPM) - 8.8418 20.000 Pass
CO2 (GPM) - 623.5632 - -
Nox (GPM) - 1.2859 9.000 Pass

Hope that helps add to your data set.

What is a GPM? Gallons Per Minute, Grains, Grams,...????:banghead:

How do we compare it to PPM? (PPM=Parts Per Million, it is a concentration based limit)

If it is Grams (mass based limit), we need a flow rate to do any useful conversions to PPM (concentration based limit).

After looking online, "GPM" appears to be "grams per mile." And I agree, a completely bizarre "unit" to use. Might have something to do with many people's opinion that the private company (Envirotest) is nothing but a scam on the taxpayers here.

Sorry my numbers don't seem to help...would be interested to see if any chemistry minded folks here can come up with a conversion to more standard units, but that "...per mile" bit seems tricky.

ColoCherokees said:

After looking online, "GPM" appears to be "grams per mile." And I agree, a completely bizarre "unit" to use. Might have something to do with many people's opinion that the private company (Envirotest) is nothing but a scam on the taxpayers here.

Sorry my numbers don't seem to help...would be interested to see if any chemistry minded folks here can come up with a conversion to more standard units, but that "...per mile" bit seems tricky.

Click to expand...

Thanks for posting it, it might be useful to others in your area with the same units.

Here, with out a volume per mile conversion and assumptions they used, from those who created the units for yours it is sort of worthless. I am a Chemical Engineer, we live and breath, and die over units, we crunch units in our sleep! LOL! The only value to us is if we convert it to unitless percent of limit values, but we still won't know who has tighter limits and how much tighter the limits are here versus there.

But we still need people to keep posting their test results here!!!!!! Please!:wave1:

SLo County, CA (bleh)

Idle(MAX) 2500rpm
HC 34(120) 22(160)
CO .29(1.00) .43(1.00)

I failed evap and egr function tho )=

Original motor never rebuilt. Doesn't burn any oil. I am the original owner.
Mileage: 340783

Ecomike said:

and details of differences from state to state or county (parish) to county ...

Click to expand...

... or test station to test station, or test tech to test tech for us Colorado folks. If you want to light a fire, just ask YELLAHEEP about it. It's a bit of a sore spot with him recently (again).

Cash for clunkers eat your heart out!

I moved so no test numbers for me this year. I moved to Gonzales county. No emission testing, YET

Here in San Diego...the SMOG Test regulations are quite strict....
The permissible levels in other states are more than double what they are here....
Here are the results of todays SMOG Test:

Just a reminder, some of us are not mind readers, so please post up you year with your data, as there are differences between 87-01.

my2monkeys,

Impressive, an 89 vintage (headed for 400,000 miles on the ticker) as well, great year!:cheers:

Thanks for the reminder....

1998 XJ 4.0L 4x4 5spd