93' coupe deville didnt pass smog
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1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 93' coupe deville didnt pass smog in Past Cadillac Vehicle Discussion; well i got my car smogged today, and it didnt pass. the report said my HC and Co2 levels were ...
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    4.9 liter beast is offline Cadillac Owners Member
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    Exclamation 93' coupe deville didnt pass smog

    well i got my car smogged today, and it didnt pass. the report said my HC and Co2 levels were fine, but my NO levels were too high for california. at the 15 mph test i had to be below 687 and i pushed out 965 and the 25 mph test i had to be below 701 and i was at 845.....any ideas? the mechanic only told me that it would cost about 250-400 to repair, but i dont see myself spending that much money right now cause i dont have it. suggestions would be great.

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    4.9 liter beast is offline Cadillac Owners Member
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    Exclamation Re: 93' coupe deville didnt pass smog

    I use 91 grade gas by the way, would that have anything to do with it? Also, does anyone know if those fuel additives that guarantee you to pass smog actually work? It seems like they would.

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    N0DIH's Avatar
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    Re: 93' coupe deville didnt pass smog

    Check timing and EGR operation.

    EGR is in place to reduce NOx emissions. High NOx is due to high combustion chamber temperatures. Reducing timing, compression, installing a LARGER cam and EGR are all factors that affect NOx emissions.

    Obviously you can't install a larger cam or knock down the compression, so check the timing and verify that it is not too high, do run recommended grade fuel as you mentioned, and ensure EGR passeges under the throttle body are clean all the way up to the EGR valve.

    Initially see if you can run a coffee pot cleaning brush through the throttle body blades into the EGR tube ("jet extensions") to clear them, this might be all you need. Run some solvent like X66P or X66A with the brush (available only at the local GM dealer for around $7).

    Oh, I prefer to always idle the car a lot in the parking lot when waiting for my turn on the smog bench. My 91 Bonneville passed at 0.00% CO, and 3 ppm HC. Good enough? It was for Colorado "Clean Air" zone at 6000+ feet.

    Tom

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    Re: 93' coupe deville didnt pass smog

    Very simple fix. Hold the throttle blades wide open. Look down the bores with a strong flashlight. See the two tubes sticking up at you from the floor of the manifold beneath the throttle blades??? Those are the EGR tubes and they should not be caked and plugged with carbon. Rod them out with a stiff piece of wire and re-test.

    Budwieser.

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    4.9 liter beast is offline Cadillac Owners Member
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    Talking Re: 93' coupe deville didnt pass smog

    you guys are awesome! im glad i found this site! anyways thanks for your help, im gonna work on that and see if the tubes are clogged, if so, i'll clear them. Just to be save i'll probably add some of that fuel additive just to make sure i pass. i really dont want to have to pay another 50 bucks if i dont have to.

    thanks again.

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    Talking Re: 93' coupe deville didnt pass smog

    by the way, how would i check/change my timing? im interested in learning about how to do this stuff.

    Thanks

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    Re: 93' coupe deville didnt pass smog

    ~ 4.9 LB: I Agree with both Tom “N0DIH” & Budweiser “bbob” on some of the Simple issues. One thing you may consider, (after you have checked the basic issues they mention) is to Flush the Cooling System and bring it back up to factory specs. As Tom states “High NOx is due to High Combustion Chamber Temperatures” my Personal Experience with Cadillac’s & BMW 5 Series of this Era is that Poor Condition of Coolant can/may play a significant cause in the Final analysis with these Aluminum Block Engines in Smog Testing! Remember that “High Combustion Chamber Temperatures” are Playing a Large Part in the High NOx Levels!

    ~ Another thing to remember/consider is the Catalytic Converter. The Older Models have 5 Precious Metals that May Not Pass in Your Specific Area and the New 7 Precious Metal Converters May meet these Requirements! The New SMOG Requirements SUCK for a Lot of Us with Slightly Older Rigs! Good Luck!

    {:{}

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    Re: 93' coupe deville didnt pass smog

    Quote Originally Posted by 4.9 liter beast
    by the way, how would i check/change my timing? im interested in learning about how to do this stuff.

    Thanks

    You should be able to pass fine without the "additive". Most of those tests in a bottle are alcohol to help with the HC and CO numbers. I doubt that it will do anything at all to help the NOx and it is a waste of money. Forget it and just clean out the tubes.

    Unless you are running VERY hot the coolant temp shouldn't affect the NOx nor the precious metal content in the cat conv.

    If you want to check the timing score a timing light and hook it up to #1 cylinder. Look under the dash just beside the steering column for the ALDL connector. Use an alligator clipped test lead or paper clip and jumper pins A and B and start the engine. This forces the PCM into the "set timing" mode and the timing as read with the light should be at 10 BTDC. If you want some more performance and don't mind premium fuel all the time loosen the distributor and bump the timing up to 13 or 14. The 4.9 has a pretty conservative spark cal and likes the additional spark but it has no knock sensor (hence the conservative spark cal....) so you will likely always have to run good gas and listen carefully for spark knock. If it knocks then just back off a degree and try it there. For insurance you could retard the spark to 7 or 8 degrees for the emission test to help the NOx but I am about 90% sure that cleaning the EGR tubes alone will fix the problem.

    Not to downplay the importance of refreshing the cooling system and using the coolant supplement pellets. The single most important thing for the long life of a 4.9 is fresh coolant and the coolant supplement pellets. This keeps the corrosion inhibitors in the coolant up to full strength and seals the cooling system to prevent any internal leaks into the oil that can cause premature engine wear. It probably won't help the emissions but it will certainly keep the engine alive longer.

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    Re: 93' coupe deville didnt pass smog

    Quote Originally Posted by Skullman

    ~ Another thing to remember/consider is the Catalytic Converter. The Older Models have 5 Precious Metals that May Not Pass in Your Specific Area and the New 7 Precious Metal Converters May meet these Requirements! The New SMOG Requirements SUCK for a Lot of Us with Slightly Older Rigs! Good Luck!

    {:{}

    I know about platinum, palladium and rhodium in the cats but what are the other 2 or 4 "precious metals" you mention??

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    Re: 93' coupe deville didnt pass smog

    I also live in Southern California and my NOx was around 3000 ppm . I ended up having to hook the EGR straight to vacuum so that it would dump a whole bunch of exhaust down the intake manifold and setting the timing back something like 20-30 degrees. Even then, it barely passed on the NOx. Looks like yours is close enough to passing that you will probably pass after following the advice above.

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    Re: 93' coupe deville didnt pass smog

    Quote Originally Posted by bbob
    I know about platinum, palladium and rhodium in the cats but what are the other 2 or 4 "precious metals" you mention??
    ~ First off, I have to ask where you’re at? Here in Cali, especially in the major metropolitan areas the "Smog Laws" are quite intense (I’m in the SF Bay Area). If you reside in Cali. I can understand that you could miss this just as I did. My Catalytic Converter went out and I hit one of my Muffler Shop Buddies up and found this out. I chose Not to follow what Cali Regs are and went with the 5 instead of the 7 'cause I can change registration to another county. Another C-Note for the 7 was not worth being in the Bay Area Reg wise. Please understand that we have run these vehicles thru the system and My Peach Puff will NOT Pass Cali Smog with the 5 Cat! (In the Major Metro Areas) And I SHIT You NOT that Flushing and Bringing Up to Specs Does Work! With these Era Cads & 5 Series BMW’s! Well, here in Cali anyway! I can’t tell you right now as to the other “precious Metal” as I’m down at the Ranch but I will attempt to find out and post. I do know that Cali Smog Reg Laws does talk about them for Us and our older Rigs so as to pass. My understanding has always been that we only had to meet the Requirements of the Year, but here in Cali that has changed!?

    ~ So, Please tell us what’s your background!? “Since you obviously have knowledge!”

    ~ For the Record, I played with BMW’s for a number of years and the Dealership group asked me to play with Cady’s in the mid to late 80’s.

    {:{}

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    Re: 93' coupe deville didnt pass smog

    Quote Originally Posted by Edahall
    I also live in Southern California. ~SNIP! Bla Bla Bla
    ~ I still can't get over the Look of your Rig! Damn, I think those Land Rover Wheels Really Make your Rig! Just My 13 Cents Worth!!!! Nice Rig!!

    {:{}

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    4.9 liter beast is offline Cadillac Owners Member
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    Exclamation Re: 93' coupe deville didnt pass smog

    Well, today after my math final i was on a mission to clean my throttle body and tubes. I opened up the throttle body and i was disgusted! i couldnt believe how much crap i found clogging the tubes. One tube actually buried underneath a pile of "black" haha. i didnt have any pipe cleaner, but i did have some left over throttle body cleaner spray from my last car so i did an initial cleaning using a flathead screwdriver down the tubes, then when i couldnt get anymore out using the screwdriver, i sprayed some throttle body cleaner down the tubes and on the basic surface of the throttle body and throttle body plates. I started it up and let it idle for about 10 minutes while cleaned my wheels up a little. drove it to work fine. One thing i did learn today was that if your car doesnt pass smog when you first buy it from someone, you can actually have the previous owner pay to have it smog legal. i was shocked. So basically i called the previous owner up (i just bought the car no more than 3 weeks ago) and told him it was law to either sell me a smog legal car or pay for the smog inspection/mechanical work and parts. He agreed that he would pay to have my car resmogged and pay for anything needed to be fixed in order for it to pass smog. I was shocked that this was a california law (i live in SF). Im having the smog re-test done thursday at a local shop with nothing more done to the car other than the cleaning of the throttle body. I hope it passes. I'll post the numbers up to show how much/little the actual cleaning did as compared to it not being cleaned.

    Thanks again for all your help guys. This site could potentially save me A LOT of money haha.

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    BeelzeBob's Avatar
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    Re: 93' coupe deville didnt pass smog

    Quote Originally Posted by 4.9 liter beast
    Well, today after my math final i was on a mission to clean my throttle body and tubes. I opened up the throttle body and i was disgusted! i couldnt believe how much crap i found clogging the tubes. One tube actually buried underneath a pile of "black" haha. i didnt have any pipe cleaner, but i did have some left over throttle body cleaner spray from my last car so i did an initial cleaning using a flathead screwdriver down the tubes, then when i couldnt get anymore out using the screwdriver, i sprayed some throttle body cleaner down the tubes and on the basic surface of the throttle body and throttle body plates. I started it up and let it idle for about 10 minutes while cleaned my wheels up a little. drove it to work fine. One thing i did learn today was that if your car doesnt pass smog when you first buy it from someone, you can actually have the previous owner pay to have it smog legal. i was shocked. So basically i called the previous owner up (i just bought the car no more than 3 weeks ago) and told him it was law to either sell me a smog legal car or pay for the smog inspection/mechanical work and parts. He agreed that he would pay to have my car resmogged and pay for anything needed to be fixed in order for it to pass smog. I was shocked that this was a california law (i live in SF). Im having the smog re-test done thursday at a local shop with nothing more done to the car other than the cleaning of the throttle body. I hope it passes. I'll post the numbers up to show how much/little the actual cleaning did as compared to it not being cleaned.

    Thanks again for all your help guys. This site could potentially save me A LOT of money haha.

    Just cleaning the throttle body is not likely to help the NOx problem with the smog test.... It will help the idle and stalling and such.

    You have to get the tubes clean all the way thru. If they are clogged badly then they may still be clogged near the bottom if you cannot run a stiff wire all the way thru them (they are 1.5 to 2 inches long into the manifold). Ram the wire thru until it bottoms in the passage in the manifold below the tubes...you cannot hurt anything...but it is important that the tubes are open and unobstructed all the way thru.

    In some cases where there is heavy buildup in the tubes it is necessary to remove the throttle body and use a drill bit to clean the carbon out.


    Tell the previous owner that he has to buy the case of Budweiser.....LOL.

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