Bill Ball

Here are my smog test results.

LIMITS
SPEED-------------------------------HC----CO----NO---
15 mph-----------------------------110---0.71---772
25 mph------------------------------85---0.59---711

RESULTS TEST #1
SPEED----RPM----%CO2--%O2---HC----CO-----NO---
15 mph---1377----13.4----2.2----56----0.05---836
25 mph---1210----13.3----2.3----39----0.03---961
Failed NO. This looked like a lean condition. I found a bad o-ring at the base of one injector. Thought that must have leaned out that cylinder and I had found the problem.

RESULTS TEST #2
SPEED----RPM----%CO2--%O2---HC----CO-----NO---
15 mph---1401----13.2----2.4----90----0.06---1112
25 mph---1275----13.2----2.2----57----0.03---1057
Argh! Worse than previously. So, I changed out the O2 sensor as there is a possibility I installed a bad one from my pile of spare parts when I removed the Wideband and X-pipe. Also, ran a can of "Guaranteed to Pass" in the fuel and changed the spark plugs.

RESULTS TEST #3
SPEED----RPM----%CO2--%O2---HC---CO-----NO---
15 mph---1385----13.1----2.3---113---0.06---867
25 mph---1429----13.2----2.1----85---0.07---690

UPDATE 5/20/2013 TEST #4
SPEED----RPM----%CO2--%O2---HC---CO-----NO---
15 mph---1369----13.6----1.9----70---0.17---244
25 mph---1187----13.6----1.8----52---0.09---144

This is with borrowed lower mileage cats and copper plugs. 02 is still high and HC is not super clean, so I think I still have something to pursue, but HALLELUJA, I PASSED!



Historically HCs have always been high with this car, barely passing. Last time 2 years ago NO was in the 500s, passing easily and improved over results from much earliers tests.

Spark plug wires, caps and rotors are near new. Plugs are brand new (between tests 2 and 3) platinum 4. I guess I could put some coppers in but I've never considered plug type an issue. Engine is running on the cool side in this cold (for California) weather. It was around 60F today. I've had one of the low temp T-stats in for 8 or 9 years. Note that several months ago I swapped out my original fuel injectors for 4-hole type for no particular reason other than the originals were approaching 250K miles with no service. Maybe I should reinstall the old injectors.

Not sure what to look at next.

kevinlieb

Time for a new Cat? Or just get the car far warmer? If the cat is not heated up it is not fully doing its job.

Randy V

As you know, high NOx is typically caused by lean fuel condition.

I'd look at fuel pump, fuel dampeners, fuel regulator, fuel filter, etc.

This might help you get started in the right direction:

http://www.smogtips.com/failed-high-...rous-oxide.cfm

Ducman82

I would try some standard plugs. I have seen "expensive" plugs suck power an mileage due to the ignition system not liking them

Erik N

Superinflate your tires. Like train wheels with zero resistance. Worked for me many times.

Remember that time after Marble Falls a few years ago?, When you and Dan idled past like nothing had happened?

I was glad to take one for the team.

See you next time, Mr. Ball

Mike Simard

Here's something that may be relevant:

http://www.nichols.nu/tip766.htm

I'd understood engine temperature being cool as a problem for emmision tests but this mentions NO specifically.

Hilton

You're running lean, so its time to start eliminating the likely causes.. having just been through 6 comprehensive emissions tests and had results all over the board, you have my sympathies!

Are you *sure* your O2 sensor is ok? (if the O2 loop is working, car should be at 14.7 under cruise.. unless its not getting as much fuel as it thinks it is)

How old is your MAF? (this is the most likely suspect)
Does your Temp II check out ok?
Is your fuel pressure at idle ok?
Are your hall sender and both knock sensors working? (retarding timing raises EGT's - which raises NOx - so a 6 degree ECU retard due to a failed sensor will hurt NOx)
Are your maps stock?

edit: Your 4-hole injectors likely won't be hurting - which part number are they? Most 4-hole injectors are faster than the stock ones, which will make the car run richer at WOT etc., and tend towards richer during normal running, but should be compensatable by O2 sensor)

joejoe

Not sure if this will help or not, but recently bought another '86.5 which had failed smog due to high nox. 2082 measured at 15mph (1106 max) and 1494 measured at 25mph (936 max) Changed plugs with oem copper, changed oil, adjusted MAF, ohmed plug wires. Car passed with 15mph measured 0174, and 25mph measured 0330. The MAF was way out of spec according to kens' blinkr' and I did put some 'guaranteed to pass' in (always do this for the 'P' cars I have before smog) Smog tech did say car was a bit lean still and this proved correct with blinkr' after smog so have replaced with another I have. The one I pulled from car ohmed at 979 so was almost to end of adjustment. The one put in ended up at 562 after adjusting again with blinkr'. I do think copper plugs make a big difference, but maybe I am wrong.

Richard S

If you want to try a different cat, I have an extra stock one you can throw on there.

Rich

GregBBRD

Very typical, for these vehicles. A good/new O2 sensor pulls them very lean and the NOX goes crazy. Most of the ones I see with this problem are running leaner than 14.7.

Anything you can to to reduce the combustion chamber temperatures will help. Colder spark plugs (throw those Platinum 4 things in the trash, BTW), octane booster, increased fuel delivery. If you've got a bunch of carbon built up from in town cruising around, carbon cleaning the engine (reduce compression ratio) will help.

A really quick and simple way would be to change the "target" map to a slightly richer setting, with a Sharktuner. The car will run better, at really light throttle positions (cruising down the freeway), when you are done, too.

danglerb

What are the chances of collecting on that "guaranteed to pass stuff"?

I would go with copper plugs and a factory thermostat.

Bill Ball

Hah, hah.

Bill Ball

Thanks for all the suggestions.

Well, I definitely thought lean condition initially, and I guess that's first on the list, even with the HC high. The MAF is maybe 10 years old, so that's a good candidate. I have a spare. I guess I'll pop the wideband back in and see what a MAF change does. Last time I had the wideband in, the car was not running lean.

The chambers could be carboned up, although I think most of you know the car gets driven pretty hard.

Of course the original cats could finally be giving up, although they did a decent job 2 years ago. So, thanks for the offer, Rich.

Can someone comment on the O2 level in my test results. I've seen some comments that 2-3% is high and also indicates a lean condition, along with low CO. I don't have any apparent vacuum leaks, but I will check that too.

Oh, and I should run my Theo's 928 Diagnostic on it to verify temp II, Hall and knock sensor operation. They were fine last time I checked a year or so ago.

OK, copper plugs too. What the heck.

BarryW

My money is on the cats.

Randy V

That's typically the last place to look at when in a high NOx condition.