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View Full Version : 1994 325i Can't Pass Smog - High HC



synik
03-14-2013, 01:26 PM
ive been in the process of buying this car, which was supposed to pass smog fine but to the seller's surprise its not passing because of high hc. we made a contract that if it does not pass they will refund the money and they have been working with us. initially the seller was told to get spark plugs to fix it which we did (they paid for) but that didnt do it and now this same mechanic has told the seller that it needs a new muffler to pass. this sounds to me like it wouldnt fix high hc at all and is a waste of money (150)... however the muffler does need to be replaced (it's loud). I'm taking the car back to them tomorrow to get this muffler installed and watch it (i'm sure) fail again.. what can i suggest them to do? i realize they want to sell the car as much as i want to own it but i cant afford to pay for a new a bunch of crap to get it to pass smog... and neither can they really.

now, the car does have some electrical/computer possibly sensor issues.... the computer screen will give faulty readouts saying CHECK COOLANT LEVEL, but the coolant seems fine. Also, it will shoot out TAIL LIGHT FAILUREs and while i've checked the back lights and most of the time they seem to be on, one time one of them was out... so it does have electrical/sensor issues going on...

anyway, from my research ive found that high hc could potentially relate to a whole sleu of things, none of which seem to be the muffler. The o2 sensors can be bad, the hoses might need to be replaced, the coolant sensor might be malfunctioning, there might be a computer problem, or the final most likely fix it seems ive read about is that you need to replace the catalytic converter which is about a 500 job. if none of that fixes it then theres probably a leak in the engine somewhere . if they had to do all this im sure they would want to try and list the car for more than i bought it for... its an icky situation. im worried they might no longer have the full cash we paid either... smog checks are such bs. any ideas on how i should proceed? I would want to push them to fix the cat converter but im sure this guy wants to only do the cheapest possible fixes... and it just doesnt seem like those are going to be enough... and a muffler doesnt seem to me like it would fix anything. heh. i guess im going to ask for my money back tomorrow unless they try to pay for a real job (like a cat replacement) and tell them to give me a call once they pass it... thanks for reading or any ideas!

granlund
03-14-2013, 01:40 PM
Coolant level can be a corroded electrical connector. If there is coolant in the reservoir, you're probably fine.

Tail lights have a tendency to malfunction because the insulation on the wiring to the trunk lid has cracked. Remove the rubber boot and check the individual wires.

As far as emissions go, ask for the actual values of HC, CO and NOx from the emissions report. It's easier to make judgements on what could be wrong from seeing the actual report.

ScooterB8
03-14-2013, 04:29 PM
The basics should be done first. Spark plugs, air filter and fuel filter. It's easy enough to check the resistance across the coilpacks. I doubt a coil is the problem, but it doesn't hurt to check if they're already out to do the spark plugs (but I see that's already done). Then I'd change out the O2 sensors.

LOL!!! What kind of mechanic is this that says the muffler is causing high HC? I don't think I've heard that before. Also, the car should be taken for a good drive before the test to ensure the catalytic converter is heated up to be working properly.

s1dc9
03-14-2013, 06:16 PM
A standard tune up always solves the problem, like ScooterB8 mentioned : spark plugs, air filter, oil change, oil filter, tire pressure and make sure your PSI is according to what is on the tires or a bit less as air expands. I would hold of on the fuel filter and just run some 91 Chevron fuel for a few days prior to testing. And make sure your cats are hot... drive on the freeway for about 30 mins or so. The cats need enough run time to get up to hot temps. This should solve your problem. Take your car to a muffler shop to get a leak test done (many places do this for free). As far as it being loud, it's just the baffle that has reached it's end of life. My car is loud too, people think I have a header and it still passed with out replacing it :D As for the coolant level, it might need a new level sensor(start with that).