# Game Plan for Smog Test

**URL:** <https://community.cartalk.com/t/game-plan-for-smog-test/71223>\
**Category:** Maintenance/Repairs\
**Tags:** jimmy, gmc\
**Created:** [March 1, 2012, 12:57am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223 "2012-03-01T00:57:45Z")\
**Posts on this page:** 16\
**Page:** 1

<div class="post-metadata">

**Author:** ![Doug\_94965](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Doug\_94965](https://community.cartalk.com/u/Doug_94965)\
**Post date:** [March 1, 2012, 12:57am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/1 "2012-03-01T00:57:45Z")

</div>

I have a 2000 GMC Jimmy 2WD with 140k miles on it but now only drive 3-4k/yr so I really don’t want to replace it or dump $$ into it. Last year I passed the smog test but was close on the hydrocarbon limit (I did nothing before the test). Here’s what I’m considering…  
New air filter  
Use either Run Blue Sky Clean Air or Prestone Emissions Reducer  
Oil was changed \<500 miles ago  
Use premium gas in a \<1/2 full tank  
Check tire inflation, gas cap is on completely  
Go to the test with a hot engine (keep it warm while in line)

I do understand the purpose of the smog test…but have to weight the cost (and environmental impact) of a new car vs using the existing 3k/year… I’d possibly a different outlook if I were driving 20k/yr.

Any suggestions on the test?

---

<div class="post-metadata">

**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\
**Post date:** [March 1, 2012, 1:05am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/2 "2012-03-01T01:05:22Z")

</div>

Don’t bother using premium. Run whatever cleaner through a complete tank of gas before the test. Run the car 15 miles out and 15 miles back the day before. Don’t bother trying to keep it warm while in line because idling cools it down anyway. They have to get the system warm before making the test and it’s done by running at a higher engine speed. You should pass as long as a malfunction indicator light is not on.

---

<div class="post-metadata">

**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\
**Post date:** [March 1, 2012, 1:29am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/3 "2012-03-01T01:29:31Z")

</div>

Premium isn’t going to help you one bit.

Try something like SeaFoam.

If you think your air filter is bad then consider changing it.

---

<div class="post-metadata">

**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\
**Post date:** [March 1, 2012, 2:23am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/4 "2012-03-01T02:23:49Z")

</div>

Premium will do nothing for you.

My suggestions are to get the maintenance up to date and take it for a good highway drive prior to the test.

---

<div class="post-metadata">

**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\
**Post date:** [March 1, 2012, 7:21am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/5 "2012-03-01T07:21:22Z")

</div>

If the CEL is on, you will not pass. This is a 2000 model, and the ODB-II system checks the emissions itself. If it will not pass, the CEL comes on. If the CEL is off, the only other thing to worry about is the safety check if your jurisdiction does that. They check for cracked windsheild, worn tires, worn brakes, sloppy suspension and extent of rust.

---

<div class="post-metadata">

**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\
**Post date:** [March 1, 2012, 7:23am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/6 "2012-03-01T07:23:03Z")

</div>

Happiness in a 12 oz bottle…Good Luck…When is the last time you changed your spark plugs?

---

<div class="post-metadata">

**Author:** ![Doug\_94965](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Doug\_94965](https://community.cartalk.com/u/Doug_94965)\
**Post date:** [March 1, 2012, 7:37am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/7 "2012-03-01T07:37:49Z")

</div>

What is CEL? The vehicle is running perfectly and is well maintained (at least visually + basic fluid changes).  
Good idea - will do the plugs.  
Thanks

---

<div class="post-metadata">

**Author:** ![Doug\_94965](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Doug\_94965](https://community.cartalk.com/u/Doug_94965)\
**Post date:** [March 1, 2012, 8:00am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/8 "2012-03-01T08:00:11Z")

</div>

I was just looking over my last test - actually in 2010…and the HC at 25mph was fine, it was the HC at 15mph that was 1 PPM from the max of 50 PPM. Not sure if that sheds any light on the issue. I’ll still do the plugs.

---

<div class="post-metadata">

**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\
**Post date:** [March 1, 2012, 8:00am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/9 "2012-03-01T08:00:37Z")

</div>

CEL = ‘Check Engine’ light. If it only comes on for self-check when you start it up, then goes out, you have nothing to worry about emissions-wise.

---

<div class="post-metadata">

**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\
**Post date:** [March 2, 2012, 9:43pm UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/10 "2012-03-02T21:43:05Z")

</div>

Maryland suggests driving the car for 30 minutes on a highway before going to the test. That’s more than just warming it up to me, but good advice.

---

<div class="post-metadata">

**Author:** ![Doug\_94965](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Doug\_94965](https://community.cartalk.com/u/Doug_94965)\
**Post date:** [March 2, 2012, 10:00pm UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/11 "2012-03-02T22:00:26Z")

</div>

Thanks everyone for the suggestions. I’ve got a tuneup scheduled.

---

<div class="post-metadata">

**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\
**Post date:** [March 2, 2012, 10:39pm UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/12 "2012-03-02T22:39:42Z")

</div>

Doug, what do you mean by tuneup? You truck should only need spark plugs and maybe spark plug wires. There’s nothing else to a tuneup with electronic ignition. You’d throw a code if your ignition was acting up.

---

<div class="post-metadata">

**Author:** ![Doug\_94965](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Doug\_94965](https://community.cartalk.com/u/Doug_94965)\
**Post date:** [March 2, 2012, 10:47pm UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/13 "2012-03-02T22:47:22Z")

</div>

Good point, I asked for a tuneup with plugs and new spark plug wires (@ 140k miles). I’ll make sure that’s clear. I did have one shop (not the one I’m headed to) say the fuel line cleaning was included…other than the fuel filter, I wasn’t sure there was much more to clean.

---

<div class="post-metadata">

**Author:** ![bennyandthejets](https://avatars.discourse-cdn.com/v4/letter/b/b487fb/32.png) [@bennyandthejets](https://community.cartalk.com/u/bennyandthejets)\
**Post date:** [March 2, 2012, 11:35pm UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/14 "2012-03-02T23:35:44Z")

</div>

I can’t say I’ve ever heard about fuel line cleaning, maybe a can of Injector cleaner will help if the injectors have any kind of build up, I think 99% of the liquid injector cleaner purchased and poured into fuel tanks does nothing more than make the vehicle owner feel good about thinking he is doing his car a favor, but that’s ok. I’ve never seen an emission machine that provides an actual measurement of hc or co when measuring obd2, unless the tail pipe is probed also which isn’t the case in my state.

---

<div class="post-metadata">

**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\
**Post date:** [March 3, 2012, 12:37am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/15 "2012-03-03T00:37:06Z")

</div>

Every state is different…many sill measure tailpipe emissions with the car running on a dyno…of course they check the OBD-2 port too…It’s a regular dog and pony show that does little or nothing to improve air quality…

---

<div class="post-metadata">

**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\
**Post date:** [March 3, 2012, 4:30am UTC](https://community.cartalk.com/t/game-plan-for-smog-test/71223/16 "2012-03-03T04:30:05Z")

</div>

I would think an oil change before the test would be a good idea, along with the 30 minute road trip.