The title says it. I failed the smog test for 15 mph and 25 mph with my HC count over the maximum. On 15 mph I was 60 ppm over and about 10 over on the 25 mph check. This basically means that I am running a little rich or maybe my cat is going bad. The cat is 5 years old so it should still be good.

I have gone over all vacuum lines and they are good. I do have my spark plugs gapped wider than recommended but I don't have any ignition problems. I do have a bad battery that I will be replacing soon but I don't think that would affect my emissions.

Any suggestions for things I should look for or do? I want to do more testing and try a few things before I buy a new cat.

Make sure there's a good ground and connections for the battery. Fluctuating or erroneous sensor voltages can give the ECM false readings. If it's the cat the NOX and the CO2 will be high too. If all the other values are well below the averages (not the maximums) then make sure the car is all the way warmed up when they test. Bad or low temp or no thermostat with a low temp fan switch, if they keep the coolant temperature below 150, will cause the engine to run rich. All the places I go to in the bay area let the engine run for 10 or 15 minutes while they prepare to do the tests just to make sure it's completely warmed up. Sometimes they wait until the fan comes on. That way they are certain it's fully warmed up and that the engine won't over heat during the actual test protocol. An exhaust leak can cause the engine to run rich but again, here in the bay area, they usually test for exhaust leaks as part of the testing set up. That a start.

[This message has been edited by Fierari (edited 03-14-2007).]

Thanks for your reply.

My car was running the whole time prior to the test.

My battery is bad. I will be exchanging it today after work. Before I exchange it, I will check the voltage with the engine running to see if the voltage fluctuating much.

My CO levels were high even though they were within the maximum. I guess that points towards the cat being bad.

This Question gets asked on a regular basis,so I save my responce to a previous post,read here:
Tips on Helping pass smog
Advanceing the timeing will cause your car to fail (a check engine light will fail),I know this because thats what they said to the guy at the smog shop,that his timeing was advanced too far (Idleing too fast).Heres a few tips to help pass the smog.
1.Allow The Car To Heat Up!!!
2.Plugs and wires can be a good investment.A failing plug will cause unburned fuel to travel out the exhaust,causeing a test failure.
3.Distributor cap and rotar,can help,but it depend on how maney miles are on the car.
4.There is a port on the inside bottom of the throttle body,spray some throttle body cleaner in there.
5.Spray some throttle body cleaner in the pivot points of the throttle body (wear safety glasses)Then force some high temperture grease into the pivot points.The throttle body has been known to stick due to varnish build up and can cause the engine to idle higher than normal causeing it to fail.
6.High mileage motors have been known to build up carbon at the EGR tube on the side that attaches to the intake,but that would most likely trigger the check engine light.
7.If your tight on the bucks $$$ then remove the EGR and carfully clean any carbone builup you may see in there.Otherwise you will need to replace the EGR periodically.You should also remove and clean or replace the pcv valve.I recomend changing to new parts periodically.
8.Set the timeing were it's suposed to be.
9.If you removed the thirmistat for some reason or another,you will need to reinstall it,because you car will take much longer to to idle down and may not idle down dureing the test.Allow the car to heat up!
10.Exhaust leaks,such as the exhaust manifold gaskets could cause the car to idle up,fix any vacume leaks you may hear or see.High Idle will usually cause it to fail.
Well, if I missed anything feel free to add more.

quote Originally posted by Doug85GT: The title says it. I failed the smog test for 15 mph and 25 mph with my HC count over the maximum. On 15 mph I was 60 ppm over and about 10 over on the 25 mph check. This basically means that I am running a little rich or maybe my cat is going bad. The cat is 5 years old so it should still be good. I have gone over all vacuum lines and they are good. I do have my spark plugs gapped wider than recommended but I don't have any ignition problems. I do have a bad battery that I will be replacing soon but I don't think that would affect my emissions. Any suggestions for things I should look for or do? I want to do more testing and try a few things before I buy a new cat.

Replace the cat and you'll pass. Look down the center of the old one when you get it off and you'll see why....

When I first saw the title, I thought that my thread was being replied to and I was not getting the emails

I have the same issue with my 88GT just much worse than yours. I just hope you don't have to go through what I am going through right now. This is a pain in the butt to say the least, but at least I will know the condition of the engine when I get done.

https://www.fiero.nl/forum/Forum2/HTML/080761.html

Mine was 10x the max allowed. I would be curious to see a scan of yours to see if they rate it in the same fashion and compare what the 2 places allow for tail pipe emissions.

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85GT 5spd ,93 Eldorado 4.9 Dual O2 Custom Chip, Archie Clutch. Custom Exhaust. MSD Everything 245/50/16's Not Your Average 4.9 Capt Fiero Com --- My Over View Cadero Pics Yellow 88GT 5spd Stock.

Oh, and change the oil, the oil filter and the air filter if you haven't done that recently. I was amazed at how much of a difference they made in HC emissions. Went from fail to pass on an '87 Ford E-150 about 5 years ago.

Had similiar problem with high idle HC on the same truck. The problem there? No thermostat. They have full time fans and at idle it would cool down the engine too much during the test and go into the warm up (rich) mode.

[This message has been edited by Fierari (edited 03-14-2007).]

After installing the new battery tonight, the car ran and idled much better. They load tested my old battery and it was dropping all the way down to 6.9 V under load!

Could a battery as bad as that cause faulty sensor readings and screw up my emissions?
Capt Fiero, I don't have my test results in front of me. I will post them tomorrow for your comparrison.

Some budy correct me if Im wrong but a bad alternater would cause the 6.9 V reading.But I did have my 86 GT have a major power drain caused by worn headlight parts (disconnect the single power source to the right and left headlight and see if that makes a diffrence).Worn headlight parts would probubly kill the battery over night.

The first thing I would do is beg, borrow or steal a scan tool and see whether the car is running consistently rich for the integrator and block learn values. If it running consistently rich then find that problem before you stick a new cat on it. It could be the O2 sensor that causing the ECM to richen the mixture.

The 6.9 V was with the battery off the car. The alternator was replaced last year and during the on car test, tested good.

The O2 sensor is only 3 years old. I bought a new one when I bought the car.


Sounds like I will be replacing the cat today. If I have time, I'll retest it today also and tell everyone the results.

If I am reading that correctly, our test is actually harder to pass than your California emissions testing. I knew our test was hard to pass but yikes I thought for all the hell I hear about California testing that you guys would for sure be worse than us.

quote Originally posted by Capt Fiero: If I am reading that correctly, our test is actually harder to pass than your California emissions testing. I knew our test was hard to pass but yikes I thought for all the hell I hear about California testing that you guys would for sure be worse than us.

Actually the tailpipe test is kinda anti climatic around here. As the techs I've talked to have said if the engine is mechanically sound and all the required emissions components are present and functional they almost can't fail the tailpipe test. The problems are the visual and functional tests. If the check engine light doesn't work right that's a fail. If the EGR valve is not functional even though the NOX level is low that's a fail. If the timing is off that's a fail. If your gas cap doesn't seal correctly that's a fail. And Fieros are a "high pollution profile" car so, at least in the SF bay area, you get the privilege paying extra to go to test only stations where they are not allowed to tell you anything. They just give you the test report. That's the type of BS that pisses you off.

We also have the gas cap test, however they have done away with most of the visual stuff. 84-87 can even have a straight pipe instead of a cat, 88 however does have to have a cat converter. As for the rest of the stuff. They don't care what motor you have, or even if the check engine light is on for a Fiero. As long as you can meet or exceed the OEM specs for tail pipe emissions your car is fine. They get picky with newer cars but our older Fiero's are allowed to tweak them. We have gotten creative with getting cars to pass the tail pipe test with no cat, no EGR and removal of all other emissions equip and still getting it to burn clean. I fill the tank up with 94oct 10% alcohol blended fuel and maybe add an extra liter (quart) of pure alcohol to the tank before we take it in for testing. My 88GT failed because it had really low compression on one cylinder causing an incomplete burn which was spurting fuel out the tail pipe. (reason for my HC were 10x the allowed limit)

Edit to add pic from fuel pump.
This was back when gas was at least a bit cheaper at .96 cents per litre. Its now $1.08 for regular 90oct and up to 1.21 for Premium 94oct at the pumps.

[This message has been edited by Capt Fiero (edited 03-16-2007).]