highmileage

well I took old faithful in for its first smog in 6 years, and she failed
by almost double if not more
the breakdown:
hydrocarbons: allowable 103 max, mine 181
CO%: allowable .93 max, mine 3.27
PPM: allowable 711 max, mine 1532
Is there anyone out there who has had this happen all I know is the high CO% is a running rich problem, and the hydrocarbons are some type of heat issue

AVjeeper

I have an 89 XJ and have had my failed smog days as well. Champion copper plugs, cap & rotor and wires are the obvious.

Additionally I replaced the EGR solenoid, little gizmo on the driver's inner fender with vacuum line coming out of it. I carefully cracked open my EGR transducer (UFO looking thing) and cleaned the carbon off with soap and a soft tooth brush. Take the EGR off the intake manifold and make sure it is not clogged. You can test your EGR solenoid with a vacuum guage as well. I put on a new Cat. I also drilled two 1/16" holes in the exhuast pipe just after the muffler to suck in some fresh air for the smog probe.

Check for cracked exhaust manifold or faulty O2 sensor?

Did you try scanning it for bad sensor readings?

Here's a good link for sensors:
http://www.lunghd.com/Tech_Articles/...iagnostics.htm

I'm sure there are other things someone else may chime in with.
Good luck.

highmileage

EGR works fine but do not know about the solenoid O2 sensor was replaced last week in prep for smog check for manifold cracks tomorrow..... thats what that plastic disc is called (never new it had a name) have to replace hoses going to the charcoal can. does have one issue that's odd high idle whenever it feels like it goes from normal (400 - 600) to around 1100 after warm up not all the time but often enough to notice.....cool idea for the holes

cruiser54

Sounds like your TPS is beginning to fail.
O2 sensor could have fixed it. Was your idle rougher before replacing it?

Make sure your intake manifold bolts aren't loose.

Carefully inspect the hose from your throttle body to the MAP sensor on the firewall. Low vacuum to the MAP will cause rich running.

akita8

Could also be the fuel pressure regulator. Pull the vacuum line off the regulator and see if it smells like gas. It's possible for the regulator to operate normal but have a pinhole in the diaphram and introduce fuel directly into the manifold through the vacuum line.

cruiser54

Good point. All these things are easy to check/perform.

rrich

"""""hydrocarbons: allowable 103 max, mine 181
CO%: allowable .93 max, mine 3.27
PPM: allowable 711 max, mine 1532"""""

Easy - CO is too high because of a vacuum leak. Too much oxygen getting on O2 sensor - computer richens it way up.

HC is up because of a rich misfire - CO too high.

NOx is up because the vacuum leak is affecting 1 or 2 cylinders, making them too lean - too hot.

Do intake smoke test to find the leak.
Do exhaust smoke test to check for exhaust leak.

Intake test - engine off, rag in throttle body - put a hose on an intake port - blow smoke through it. Fix wherever it comes out.

Exhaust test - wet rag in tailpipe (pressurizes system), a few squirts of oil in the throttle body to make it smoke, start engine, go under with a strong flashlight - fix where the smoke comes out.

And if still fails, test cat - use infra-red thermometer - measure cat's inlet and outlet temps - outlet should be at least 100 degrees HOTTER than inlet IF cat's working.

highmileage

TPS checks out fine,
fixed VAC leaks (had to rebuild the vac harness)
MAP sensor in great shape
fuel pressure regulator working, no leak
EGR solenoid working
no leaks at intake
idle is now under control
still have to check the exhaust maifold for leaks (cracks) and please don't be the cat
thanks for the help guys

cruiser54

Way to get after it!!

highmileage

had to change the exhaust manifold it might as well have come off in three pieces.
changed the O2 sensor just because I was there
did a relocation of the MAT to the air box (WOW WHAT A DIFFERENCE)
engine smoothed out and idle came down to a respectable 4 to 600 rev's
all that's left is the cat (if it needs it, please no)

cruiser54

What did you notice by relocating the MAT sensor?

highmileage

smoother throttle
idle doesn't move around as much
gas mileage may have gone up a little
But then that could be having fixed all the other problems
the idle though was and always has been all over the map and now it's not, so it may have helped there.

rrich

post #7
"""""And if still fails, test cat - use infra-red thermometer - measure cat's inlet and outlet temps - outlet should be at least 100 degrees HOTTER than inlet IF cat's working. """""

highmileage

Update........ finally passed last week on retest 426,019 miles when it rolled onto the dyno. Passed everything by half except the low speed HC 103 was fail 98 was mine, tech said it was the cat going out.

DFlintstone

And the crowd Cheers! Well done. (High five High Mi)'


Hydrocarbons are just unburnt fuel Btw. Any little miss is one of the things that will send it sky high.

I'm not in a smog control district up here so we only need to smog once when we first register. Your story gives me hope that my old thing might pass if they change that.