So i was do for a Smog test,and was confident in the truck that will pass as the engine was running really good, in the last 2 years and only added about 4200 miles, also no check engine light ! in last 2 years , i have done smog in jan 2012 and passed ok.

Anyway , today not sure if this has something to do with it,i put some 91 grade gas ,about $25 and drove the truck about 8-10 miles then went to smog , and off course it failed.

They said that NO (PPM) is to high!

*15 mph
max 699
ave 393
meas 1096
fail

*25 mph
max 601
ave 293
meas 636
fail



Also the smog guy said that my check engine light come on to the end of testing and then went off, he said most of the
time it happens when testing trucks because they are rear drive...but even with that light coming and going away
it still passed that function,so he said not to worry! I never from the last smog done had any check engine light!.


History of things done on the truck:

*12/21/2011 oil and filter where changed , miles: 235.200 (10-w40)
*2/10/2012 air valve was changed
*2/26/2012 spark plug wires and plugs where changed
*7/20/2012 oil and filter changed at 238.185
*10/7/2012 changed spark plug wires and plugs again as the old once start to crack
(changed under warranty at autozone)
*4/14/2013 changed oil and filter , miles 241.215

And i guess i am due for a oil change ,now or within 100 miles.

So now related to that high emission,what will be best to start? Engine runs okay,no check engine light.

The guy at the smog place said even if i burn all the 91 grade gas out and put back 87 unleaded , the emission may come
very little down but not too much and i still need to figure out ,what is causing this! He said to take a look at Cat,O2 Sensors ...

The truck is not smoking or anything.

Please let me know what will be your guys advice!

Thank you and appreciate your time to reply.

Regards.


1995 Dodge Ram 1500 5.2L 2 Wheel drive.

 

Have you ever changed the 02 sensors ?, if not, that is one thing that needs to be done.
If your cat converter is also original with over 200.000 miles on it, it needs to be replaced also. These parts go bad over time and many miles, but don`t always throw a code.

 

Its possible its the O2 sensor if its the original one from when the truck was new. i know when my 98 dakota had a bad o2 the exhaust smelled rich and it didnt throw a code. might be worth a shot changing it.

 

It will be worth changing it simply due to the age.

Have you fixed your plenum yet? Burning oil would give you some truly ugly results.

 

@ Ram_Driver, cjantczak, HeyYou, really appreciate for advice !...

Well i had to call my brother to get more info history (he purchased in 2001) me i only had the truck for about less than 3 years ,only as a reserve as i had other dodge ram ,newer and i have sold it so i am back at this one for a little while )

So my brother told me that about 10 years ago , he did a transmission rebuild and when they install it back or take it out they damage the o2 sensor on the CAT and they have replaced that one so i guess it was in 2003, as for the CAT, He had some smog problems in Oregon where he used to live ,so he put a new CAT about 5 years ago, i can see that is hand weld if i look under (so it was changed in 2007,2008) .

Recap:

O2 changed about 10 years ago (1 O2 on the truck - it had about 160.000 miles)
CAT changed about 5 years ago (1 CAT on the truck- plus flowmaster)


@HeyYou, i never got the chance to change that plenum yet!,hopefully soon, i know that is a must at this age.


Thank you,

 

Plenum, O2 sensors... Good things to do regardless.

Honestly, when I lived in an emissions area i always had to change my oil before I'd get it tested.

No oil change? Fail. Every. Time.

Change the oil? Pass!

The oil collects dirt and contaminants while you drive; it's one of the main reasons why you change it (breakdown being the other). So when you get the emissions tested, the oil at the end of its life is both breaking down itself and releasing those captured contaminants and pollutants. Fresh oil is free of those contaminants, so there's nothing to release.

If you're just 100 miles away from being due, go change it and try again.

I'm sure some will say that the impact of an oil change is negligible in emissions testing... I'm just sharing my experience and theory.

 

@Twmays, Yes i may do that and try again!...

What oil will be best ? from Auto Zone,Napa or o'reilly auto parts?
i used 10w-40 regular oil last time!

And do i need to drive the truck 15-20 miles ? before going to the smog shop or drive little more to make sure that engine is hot...

Thanks!.

 

I would change the oil and filter. And take the vehicle out for a long road test before doing the smog test. This way the engine is already at operating temp. And since you have a 5.2 engine, I would also have the timing checked too. On some engines the timing is checked with a scanner to set the syn timing.

 

Hmm, since you said "timing check" i know that they suppose to do it with a gun to make sure is at 10 degrees i think ,and i watch the guy and he never did it , so i ask him why not ,and he said that is not required anymore, i guess maybe the OBD2 wire will tell them? , no clue...

And yes,will be driving to hills little to get it really ready for smog....

Thanks,

 

Use whatever you usually like. Point isn't some "right" oil, just clean oil.

Just up to temp, make sure it's not in open loop. (And we are back to replacing the front O2 to control air/fuel mix)