I smog my 95 oddessy and I fail on hydrocarbon the first time I smog. The second time I smog I replace spark plugs , spark plug wire, PVC valve, distributor cap and rotor, oil change, chevron gas treatment, throttle body clean, switch o2 to another good used. After all this I took it to the the same smog guy for a manual test and he tested and said that the HC level are still high. I was there to see. The HC level drop down near the max leaves but that was will over a Min. into running it and he said it's taking too long . Here are the result list on the bottom. What should I try next?

15mph- (Hc) max 63, meas 99 (co) max 0.46, meas 0.09. (No) max 517, meas 140
25mph- (Hc) max 38, meas 95. (Co) max 0.56, meas 0.06 (No) max 770, meas 141
15/25mph co2: 14.3 o2: 0.0

 

 

Give me a call, I've got something I'd like you to try. Number in the sig or pm me your number.

 

Already did the chevron cleaner. I'm sure they are similar.

 

what was the co2 and o2?

 

Not quite.

Alcohol burns cleaner (HC) and cooler (NOx) than gas. It's mostly alcohol. You can achieve a similar effect with excessive Iso HEET in the tank, or add a gallon of E85 to a nearly full tank.

It's cheating, since fuel isn't tested.

However, take up the offer and contact Andy. He's probably got something much better than any OTS product.

 

For both 15 and 25mph. Co2 was 14.3 and o2 was 0.0.

 

I have buddy's that try e85 and rubbing alcohol method a while back. It lower Hc but will raise NO's a lot to not passing.

 

15mph- (Hc) max 63, meas 99 (co) max 0.46, meas 0.09. (No) max 517, meas 140
25mph- (Hc) max 38, meas 95. (Co) max 0.56, meas 0.06 (No) max 770, meas 141
15/25mph co2: 14.3 o2: 0.0

O2 should be .5%
CO2 should be 15%
CO should be .01%
NOx should be higher.

HC is high from an incomplete burn, and from the non-existent O2 and low CO2 it appears that the car is running a bit rich.
Check that the air filter is clear, there are no air leaks in the exhaust causing a false lean signal, and that the ignition system is not worn.

If the HCs or the emissions in general are improving as the test carries on, verify that the engine and drivertrain are hot prior to the test. If the Thermostat is stuck open the car will run cooler, and may run so cool as to prevent closed loop operation.
Check the temp gauge, during normal driving is it at least to this level?


Preferably the temp should read 2/3 up to the mid point on the dash gauge.

Let the van idle and wait for the fans to turn on by themselves.

 

Yes, the fan does kick on and the temp gauge is alway a little under the half part when at normal operation.

 

do a valve lash adjustment, and double check base ignition timing.

to me it appears that valve lash is not within spec, and the ignition timing is probably too retarded.

 

Base timing is good. I'll have to check the valve adjustment . Can being too loose to too tight can cause this?

 

yes. because if they are set unevenly between cylinders, some cyls will run lean and some rich, and the o2 will pick up on that and set a trim, usually a positive trim making it richer in all cyls. so the rich cyls will run even richer. this is especially the case if some valves are within spec and some are too loose, which effectively lowers the duration of the cam making the cyls with loose lash flow more air at low rpms leaning them out.
I've also seen valve seals leak oil when the lash was too tight, but not leak at all when lash was then set correctly. so if lash is too tight, it may suck some oil which will raise HC.

 

Check my valve adjustment and it was a little tight but wasn't too tight to make the valve stay open at all times. I made them all a bit looser in spec. And it made less noise. My fuel filter was clog so I replace it. Will a new cat help?

 

a new cat always helps

 

ok, so i put in a new cat and gave it another shot. here are the results:

15mph- (Hc) max 63, meas 61 (co) max 0.46, meas 0.15. (No) max 517, meas 2
25mph- (Hc) max 38, meas 26. (Co) max 0.56, meas 0.17 (No) max 770, meas 1
15/25mph co2: 14.9 o2: 0.0

its a good thing that i barely pass, but i still want the HC problem to be fixed. i was thinking if the distributor can be the problem. can the coil or ignitor be slightly bad to cause this?? i was thinking this can be a minor misfire from a weak spark??