Mechanics

CAN'T PASS EMISSIONS

Dodge Other

Hi, I have a '73 Dodge Challenger with a 318, automatic. Mileage is 127,232mi.
We took it Friday to have it tested, and it passed everything except the HC on the idle. Initial readings were:Loaded HC 00225/standard400
Loaded CO 3.58/standard3.75, Idle CO 3.02/standard5.00, Idle HC 00738/standard400
They retarded the timing to zero, and the readings changed to Loaded HC 192, Loaded CO 3.54, Idle CO0.80,Idle HC 2436, which is triple what it was to begin with! What do you suggest? Everything else looks pretty good, I think. Thanks for any info. I need this to pass as it is my daily driver, and I can't qualify for a waiver, as it hasn't been registered in this state for a year yet.







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Angelbez
September 30, 2007.



I think if you change the oil and have a fresh set of plugs, PCV it should make it. Let it warm up full before the test, and don't shut it off till it's over!

Merlin2021
Sep 30, 2007.
EGR's started popping up on that year-check for one-if so clean it out- It will raise the HC's at idle creating vacuum leak if its cracked opened with carbon.

As for the others as recommended follow thru. Due to oil dilution ( Gas )and the PCV valve if its mid position it will allow more air in the engine and further leans out the A/F mixture.

Rasmataz
Sep 30, 2007.
I own the EXACT same car with the EXACT same problem. Fill up with airplane gas or racing gas before you go and try not to idle in line too long to get the reading done. It is your only hope

Tiny
Ravensanctuary
Aug 15, 2009.
Think she got the sticker by now!

Merlin2021
Aug 17, 2009.
Let me clarify my early awnser to this about using airplane gas or racing gas to get to pass the emissions test.

These cars were made to run on leaded gas. Nowadays all you get is unleaded. These cars don, t run good on this stuff also too the octane ratings are lower. Without lead in the gas the valve seats will wear. Unless you have hardened seats put in. This will cause the valves to leak a bit and that means carbon will get past and with the lower octane ratings you don.T get as clean a fuel burn. The compression ratio was something like 10.5 to 1 from the factory If you fill up I would STRONGLY suggest you add a lead substitute and an octane booster like 104 octane boost to protect your valves or invest in a set of hardened seats for your heads. My car has hooker headers on it and a set of hooker thru pass glas paks the pipes come out and end right in front of the rear tires. I dont even have a egr valve so those answers are not exactly right that are suggesting that as your problem. Same goes for the pcv valve though I do have that still. I have to do the emissions thing every year new plugs tune up etc. Are not going to help very much if at all. If you are having runing problems these cars with the 318 came with a carter carb of about 650 A eldlebrock 750 will do much better for you than that thing and advance the timimg to where the car picks up and wants to miss and back it off just a touch. Dont retard the timimg that will make things worse for you. And when you wait in line for your turn at the test, keep your car in nuteral and not in gear it will keep the load off the engine and that will help emensely. There may be a few other little tricks you can do but the gas and this clarification should get you thru the test OK. The racing gas or the airplane fuel will not hurt your motor at all if anything the engine will " clean itself out" for you and will actually run alot better for awhile. I hope you take good care of your car as these things are worth around 25,000 or so nowadays if they are anywhere near original. I own a charger and a cuda along with my challenger. Good luck and enjoy your ride!

Tiny
Ravensanctuary
Aug 18, 2009.