WHY WILL MY VAN NOT PASS SMOG CHECK?

  • Tiny
  • Azmodeus
  • 1989 Dodge Van
  • V8
  • 2WD
  • automatic
  • 73,000 miles

Failed miserably, almost twice as high as passing grade. I replaced the catalytic converter two years ago and it barely passed then. (The tech said it takes several miles before it "kicks" in from being new and I'd only put 40 miles on it.)But, it passed. My EGR pump seiezed and I replaced that thinking it should now pass with flying colors. I've also replaced plugs, cap, rotor, wires, pcv valve and the oil only has 1000 mi. On it. I'm wracking my brain but for it to fail so miserably it must be something major that I'm overlooking. Any suggestions or reccomendations before I just take it to a shop? Also, no check engine or maintenance light comes on. ( They work I tested them ) Thanks

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Friday, July 6th, 2012 AT 6:28 AM

10 Replies

  • Tiny
  • hmac300
  • Expert
  • 43,623 posts

First thing to do is ifyou changed oil did you change filter as well. Also change your air filter. Then drive the vehicle about 20 miles on eway/interstate and THEN have it tested. Alot of times things go screwy with just driving down to get it checked. It should pass then.

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Friday, July 6th, 2012 AT 12:17 PM
  • Tiny
  • Wrenchtech
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  • 20,040 posts

You also need to post what the actual measurements were along with the minimum passing specs.

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Friday, July 6th, 2012 AT 12:38 PM
  • Tiny
  • Azmodeus
  • Member

All right, I get that you probably get people that have questionable intelligence, I always change the filter when I change the oil and the air filter is brand new. The HC (PPM) measured at 254 at 15 MPH, max is 122 and 157 at 25 MPH, max is 102. The NO (PPM) measured at 1755 at 15 MPH, max is 1010 and 1419 at 25 MPH, max is 870. Like I said I just changed the EGR pump and most components are less than a year old. It is just baffling me.

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Monday, July 9th, 2012 AT 4:59 AM
  • Tiny
  • Wrenchtech
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  • 20,040 posts

Yes, you are correct. That is why we have to explain things that we say sometimes.

The reason he recommended to change the oil is because HS from the fuel and combustion process get mixed with the oil and will be drawn into the intake through the PCV system so a fresh oil change will give you an advantage. The NOX gases are caused by extreme combustion temperatures which is the reason the EGR system is put there. Make sure that system is working properly and the engine temp is being regulated properly.

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Monday, July 9th, 2012 AT 9:55 AM
  • Tiny
  • Wrenchtech
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  • 20,040 posts

Typo. HS was supposed to be HC

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Monday, July 9th, 2012 AT 9:56 AM
  • Tiny
  • Azmodeus
  • Member

Only 1k since last oil change and engine temp. Is fine. Perhaps a blockage in the EGR system? Get good vacuum on the PCV side.

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Monday, July 9th, 2012 AT 10:28 PM
  • Tiny
  • hmac300
  • Expert
  • 43,623 posts

It could you could try running a coat hanger down it to clean it up. Did you drive like mentioned and have it tested then?

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Monday, July 9th, 2012 AT 10:29 PM
  • Tiny
  • Azmodeus
  • Member

Yes, that test was at full operating temp. After a freeway drive. To fail so miserably seems extreme. She only has 84500 original miles and runs great.

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Monday, July 9th, 2012 AT 10:37 PM
  • Tiny
  • Wrenchtech
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That's really not that miserable for a 23 year old car. HC is unburned fuel so ignition and compression are what you want to look at the hardest for the HC reading. You can test the EGR port by applying vacuum to the EGR at idle and see if it tries to stall.

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Monday, July 9th, 2012 AT 10:44 PM
  • Tiny
  • hmac300
  • Expert
  • 43,623 posts

Due to the age of this vehicle i'm starting to think that your valve seals may be worn or bad as that would make at leastone of them high if not theother. Really no good way to check those though without replacing them.

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Monday, July 9th, 2012 AT 10:46 PM

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