Smog Test Questions???

[Carbonics]

maybe the oil is dilluted by fuel and due to it's age and wear it burns oil - this causing increased hydrocarbon numbers - just a guess.

usually changing oil will not do something like that, nor would arx unless it really cleaned up the ring packs and there is a lot of wiggle room for oil to get by burn or something but I highly doubt it could do that.

make sure the timing is correct, if it has an EGR clean it out, if it has a PCV change it, just basically tune it up.

 

[dbdeland]

Shelby,

Check this link out on Auto-Rx web site click on the link below Auto-rx was not involved involved in this test.

Independent Field Test

 

[Quest]

(1)get a tuneup. If your van comes with a carb or TBI, give it a thorough checkup and a proper tuneup as well.

(2) check your timing, making sure that none of the vaccum related advance motors, etc. are leaking or broken.

(3) check your CAT.

(4) if you have an EGR valve, check and clean/replace it if needed.

(5) give your engine a compression check.

Judging by your description, this issue may not have any significant relevance to motor oil in general, but an old, tired engine with questionable state (tuneups, etc.) and emissions control units.

 

[Rick20]

It is likely that after running the cleaning and rinse phase, rings will seal better with the cylinder walls. But you have got to run the application miles before you will get the results. It is likely your hydrocarbon reading will drop significantly, after you are done.

 

[Quickbeam]

HC is unburned fuel. Could be caused by lots of things but most often it's related to misfire. Is this the two speed idle test or ASM Loaded Mode? What are the other gas numbers?

Also if the cat is original it's likely shot by now. The HC level isn't all that high so either the cat is bad or it's doing a heck of a job covering up some other problem like lean misfire. The EVAP system could be faulty too. Without the other gas numbers it's difficult to know.

 

[tom slick]

what were the O2 and Co2 numbers?

 

[Shelby]

Thanks Quick, that makes sense because the oil smelled so bad (like fuel). It was the 2 speed idle test. Maybe it's time for a tuneup, will new spark plugs/wires maybe help? All the other numbers were on the low end of whats normal, o2 and co2 were below average. The only thing that was high was the HC.

 

[Shelby]

I just bought an old Van because I need to drive a familty member around after a stroke. It was a great deal 800 bucks but it is a 20 year old vehicle. Anyhow, I almost failed the smog test, the "HC" which I assume is "HydroCarbons" was 119 out of 121 possible, with the average vehicle at 49. Questions-

I changed my oil before the test and added ARX, could this have made the HC go up?

My oil before the changed smelled like ****, it smelled like unburnt gas or something like that got in there. It could be a poor mix but could that also be because of dirty injectors, instead of a nice spray pattern it probably is dripping gas?

Do you think just changing your oil to a synthetic before the test might drop that number a couple notches before next one?

Other thoughts? I used ARX and Techron and I would bet those will help in the long run, but any thoughts on products that might help also?

 

[Quickbeam]

Diluted oil can cause elevated HC to some extent as can an impropely operating PCV system. You may want to change the oil again but in my experience oil isn't usually the culprit.

As for the other gases CO2 is an indicator of combustion efficieny. With a correctly operating engine/converter it should be high, around 14-15%. O2 and CO should be around half a percent. CO and O2 are inversely proportional in that a lean mixture will be high in O2 while a rich one will be low. Vice-versa on the CO. With those numbers I could calculate what your lambda (and thus your mixture) is. Since you were doing a 2 speed idle test NOx wasn't measured so it's unimportant. The bottom line is as long as the cat is fed a stoichiometric mixture and is working emissions will be at a minimum.

Tune the van up and confirm the engine is operating in closed loop with the O2 sensor cross counting. The catalyst depends on this flip flopping of the exhaust stream to operate. (I'm assuming it's a three way cat). However, a good cat will mask upstream engine problems while suffering a reduction in service life because of them. It's why changing the converter just to pass is a bad idea unless it can be proven the engine out exhaust stream is correct.

Leaky valves and bad timing can also cause high HC. As previously mentioned if the vehicle has an EVAP system it should be checked. Replace the catalyst only after everything else has been verified and be sure it's "lit" (hot) just prior to doing the next test. Good luck.

 

[Shelby]

Oh yeah I'm sure your right about the PCV not releasing pressure. The valve cover has been leaking for years according to the old owner. I'm hoping a ARX treatment might clean the PCV and the drains at the valve so maybe the oil will go into the motor more efficiently. It's a Van and working on it is a royal pain, just the estimate to repair the valve cover is 600 bucks, so I'm going to try a ARX cleaning and some stop leak stuff before considering shelling out major money. I'm going to have to double check the smog cert tommorow and post exactly what it says.

I think they did measure NOx so maybe it was the other test? I know they tested it at idle and again at x number rpm's. I'm not sure the differences between the tests. It was done at a smog only station. Anyhow, thanks for the advice I think I'm pointed in the right direction.

 

[Big Jim]

NOX is only generated under load so there is nothing to measure unless the test is done on a dyno.

You have lots of good advice here. Don't forget that high HC is from unburned gasoline (raw fuel) and is from ineffecient combustion.

It would be good to know what the other gas reading were. CO, CO2, and Oxygen. More complete information can help better understand what is going on.

 

[m2200b]

PCv valve, hose and grommet won't benefit from ARX. They're usally $2-3 each so I change them
if they're old or don't work. Look at the hood above the PCV valve for oil and dirt to show leak, look at the valve cover around the grommet for oil and dirt to show the grommet has petrified from soft sealing rubber, look at the hose for age , cracks and blockage.

 

[tom slick]

We need to know the actual numbers for HC, O2, and Co2. they are all pieces to the puzzle and without knowing them it is purely guessing at what the problem is.

 

[Shelby]

ok guys i haven't been able to login in but finally figured it out-
smog numbers
15mph- CO2 12.0 O2- 4.2 HC- 119 CO- .10 NO- 245
25mph- CO2-12.3 O2-3.5 HC-83 CO-.01 NO-324

 

[Big Jim]

It's running lean. High oxygen. Low CO. High HC. The cat must overall be working well for the CO2 to be so high.

 

[Shelby]

What kind of things can I do to help this? Where is the EGR valve? It has a weird PCV system, it looks like a hose attached to the VC.

 

[Big Jim]

I didn't notice. Did you post the vehicle make, model, year, engine size, etc? That may help us in telling you where the EGR valve is.

 

[Shelby]

It's a 1987 E150 club wagon, I think it's a 5.0.

 

[Big Jim]

Off hand I don't remember exactly where the EGR valve is on that engine. If I opened the hood (or maybe removed the "dog house" engine cover) I could easily identify it though.

I'm pretty sure that it has a large steel tube from one of the exhaust manifolds running up to it and that it is somewhere on the intake manifold, probably near the throttle body.

Anyone else know where it is on this engine?