Hello,
I've got a hand me down 1993 Ranger, 6cyl 3.0L Calif emissions 5 spd, 156K miles on original Cat. and O2 sensors.
Truck barely squeeked through smog testing the past 2 times, just failed for slightly over HC, slightly over CO and about 3X NOx.

Timing is at 10BTDC, engine does not come with an EGR system from the factory so I'm a bit stumped on how to bring down the NOx. Coolant temp is okay - truck doesn't overheat.

Ignition system is pretty new - bought motorcraft wires, cap and rotor about 4 years ago (truck has only been driven about 2,000 miles in the past 4 years). Plugs were changed in the past 4 months with Bosch Supers (normal copper plugs).

Truck has an issue with cold driveability - sputters and is gutless until fully warmed up.

I have on order
- replacement Catco catalytic converter (dual converter in series)
- Bosch O2 sensors (2 qty).

But I'm wondering if this is enough to pass smog. I'm wondering if I have some other issue, like a weak ignition that is causing the poor cold driveability, the just over the limit HC's, CO's and NOx, clogged injectors, etc.

What else should I look for/adjust/pour in the tank? The only thing left on the ignition system that would cause a weak spark is the coil or igntion resistor wire but how often do they go bad?

TIA,
Dave
ps, in calif they put the truck on a dyno to load it down. Both the 15MPH and 25MPH the truck failed just over the limits for HC, CO, and ~ 2-3X NOx.

 

When I hear high NOX, I think lean mixture. This next makes me think vaccum leaks any anything is to be considered suspect. Along with any other diagnostics (such as hooking up a vacuum gauge), have you pulled codes and if so what is showing? BTW, being slightly over on HC would not cause me to instantly think about weak ignition. I would not throw any parts at it until you've diagnosed the problem(s) and have actually confirmed a failed part. It's cheaper that way .

 

Thanks,
I haven't pulled any codes yet - still need to read the TECH stickie to see how to do it.

There has been no CEL light so would there still be a code set?

As I mentioned, the O2 sensors are original so I feel pretty safe changing those out after 156K miles. I'm thinking the Cat is dead due to the high NOx and the Oxygen concentration at the tailpipe is 0.6% which I think is high for a reduction/3-way catalytic converter.

Could definitely have a vacuum leak though. Are there any common failure points other than rubber hoses? (like intake manifold leaks?)

Dave

 

I am sure a cat will do for you. Especially if your exhaust smells rich. Heck, with that mileage, the O2's ought to go anyway.

I barely failed my emissions at the end of last year...

The stat of TX aircheck site (thru the DPS site) gave me a list of symptoms and cat convertor was mentioned for the NOx and HC that failed--barely. Your state may have the same help on the web.

Passed easily with the new convertor. At 243K miles, it probably was dead.

 

Can anyone tell me what the Calif smog limits are for a 1993 3.0L Ranger?

I'm looking at the printout from the Test Only place that failed my ranger last week and, get this, they tested it as an F150, test weight of 4500 pounds and with a 4.9L V6 ?!!

Looking through the glove box I found a smog test from 1999 and the limits for a Ranger with the 3.0L V6 were quite a bit more lenient.

Here's what the F150 max allowable limits are (which is what I was tested against)
15MPH HC 86ppm CO 0.6% NOx 494ppm
25MPH HC 51ppm CO 0.73% NOx 747ppm
Test weight 4500 pounds

Here's what the 1993 Ranger 3.0L limits were in 1999:
15MPH HC 131ppm CO 0.7% NOx 1072ppm
25MPH HC 81ppm CO 0.84% NOx 1122ppm
Test weight 3375 pounds

As you can see, the limits for HC, CO and NOx are a lot higher. I still would have failed, but not all across the board! Also the fact I was tested at 4500 pounds instead of 3200 pounds which is how the truck was tested in 1999 would likely have increased emissions!!

My numbers (again, at a test weight of 4500 pounds)
15MPH HC 119ppm CO 0.79% NOx 1360ppm
25MPH HC 50ppm CO 0.65% NOx 1115ppm

I'm kind of mad! If I had retarded the timing a couple of degrees it likely would have passed!

Anyone out there from Calif and recently had their 3.0L ranger smogged? If so, are the limits above still good?

TIA,
Dave

 

Looks like Calif. did indeed change the smog limits. When tested as the correct truck, and at the correct engine size and test weight, the limits for HC, CO and esp. NOx wasn't much higher than that for an F150, 4.9L, 4500 pound test weight. So I still would have failed.

Installed a new Cat Converter and 2 new O2 sensors. Now CO is nearly zero, NOx is WAAAAY down! (40ppm at 15mph and 0ppm at 25mph!! vs >1000ppm for both with the old cat. conv.). HC is still above average but the truck passed no problem!

 

Somewhere I have a link to the Colorado state emissions place where they walk you thru the calculations to determine if you have a dead cat. (hmmm, some phrase when you think about it). If you do the math, you can figure out if the cat is working or not, and what the expected numbers should be for one that has failed.
Go here:
http://www.colostate.edu/depts/NCVECS/index.html

Interesting that you can see what you should get vs what you actually get...
tom

 

I own a 2002 ranger and i live in california so i am exempt from smog untill 2008 which is most excellent. However, i am also the owner of a 1978 Chevy silverado that must be smogged every 2 years for registration. The truck is technically not smog legal but nobody looks close enough to fail it. It has a 350 from a 1971 chevelle which is more powerfull, a higher then stock compression ratio, the biggest RV cam you can put in there without it cackling, accel igntion, edelbrock intake manifold and carb and 14inch diameter by 5 inch tall K&N air cleaner. It has a single 3 inch exaust with a catco cat which is tottally legal. The only time the power robbing stock air cleaner and the EGR valve that cant help but leak exaust are on the truck are 30 minutes before i go to smog it and 30 minutes after i smog it.
I would like to share with you guys the last three smog tests that date back to june of 2000 and the maximum allowed emission levels that have changed over the years.

6/20/2000

HC:max=213 meas=144 CO:max=1.60 meas=1.55 NOX:max=2162 meas=287

5/24/2002

HC:max=197 meas=124 CO:max=1.60 meas=0.16 NOX:max=1513 meas=1455

4/26/2004

HC:max=197 meas=106 CO:max=1.60 meas=0.12 NOX:max=1513 meas=1500

Im showing you the 15 mph test cause the emissions are higher. As you can see in 2002 the max allowed HC dropped from 213 to 197. Now for the NOX it drastically dropped from 2162 to 1513. Now in 2000 my truck had a brand new cat and the egr valve still worked and the carb was at it stock mixture setting that wasn't supposed to be tampered with. In 2002 the CO dropped drastically from 1.55 the previous year to 0.16 because i did what i wasn't supposed and leaned out the fuel mixture on my carb. The NOX jumped up to 1455 from 287 the previous year due to the fact that my egr valve basically doesn't work but since i have a good cat it takes up the slack and it barely passes. I highly doubt i will pass this year since i almost failed for high NOX last year and i'm sure the cat isn't as good as it was the year before therefore wont take up as much slack. Cali hates old vehicles on the road and they make it hard for them to pass. How can you expect a truck that is 27 years old and has 334,000 miles on it to pass a smog test with the stock emission equipment. It's a joke...

 

Which is ironic because Calif does exempt 25+ year old cars from needing a smog test! You're still supposed to keep everything on it that came on the car when it was new, but you no longer need to test it.

I was surprised that Calif (maybe it is a federal thing) tightens up the limits. I would have thought the limits from day one would have been what the orig. mfgr. had to pass when the vehicle was built.

With the new Cat, I can't believe how low my NOx is! No EGR on this engine.

 

In california it's 30 years old that is exempt and it is not rolling as of right now, so it's currently set in stone unless something changes. The funny thing is that my truck is a 49 state federal emission truck but will still pass the test. The only difference between the federal and ca emission on my truck is the ca had to have a smog pump. Smog pumps are crap and it is the most failing emission part on any vehicle that is equiped with one. My truck actually runs better and has way more power when it's not loaded down with the easilly removable emission equipment.

 

Sorry, you're right - it's 30 years and the rolling exemption was repealed in April of 2005 :-(


"Beginning April 1, 2005, the 30-year rolling exemption will be repealed. Instead, vehicles 1975 model-year and older will be exempt. Therefore, 1976 model-year and newer vehicles will continue to be subject to biennial inspection indefinitely"

Bummer.