how to lower hydrocarbons for emissions test ?
- Thread starter jaker04
- Start date
I drove highway for 30 mins before my 2nd smog test, still failed.
i changed oil, cleaned out the filter and used GTP, still didn't pass. how do i retard the distributor? I don't have tools.
takes a wrench. There are two or three nuts or bolts. You loosen them, it has a small amount of adjustability. Enough to help, not enough to hurt anything I know this is a v6 but it's the same. \\
Don't retard the timing...a properly performed emission test will check timing as well, and fail you if it is out of spec.
Since you have no tools, and really not much knowledge of this kinda stuff...I think you'd be money ahead taking it to a shop who can properly diagnose and repair the car.
How much money have you thrown at it so far without solving anything?
When we had emissions testing my go to with an old car was to bump up the idle to near the max allowable rpm, get the motor good and hot on the highway first. Dont shut off the engine while waiting and add a liter of methyl hydrate to a 1/4 tank of fuel. Worked well on beaters that had trouble passing the test. In particular low speed or idle emissions.
Paco
Paco
- Joined
- Nov 29, 2009
- Messages
- 9,516
What exactly is the issue causing it to fail? Is the car just worn out? Does it burn oil?
The secret to pollution is dilution.
A tank of CO2 in the trunk piped into the exhaust?
A tank of CO2 in the trunk piped into the exhaust?
Altering timing or idle speed is not allowed in California. You must have the same 8BTDC (+-1) timing and the same 650 rpm idle (82 Mazda) AND Evap rated vacuum lines on anything vapor related PLUS you must have a functional EGR (the only test they do is to suck the EGR valve and see if the idle drops, you dont necessarily need it to work as designed but its gonna lower your NOx levels especially at high speed test. High HC is unburned fuel (im taking about a carbed motor here) and usually its the plugs or obviously the AF mixture screw on the carb but many are sealed here so very little adjustment is possible unless you break the limiter off and manually turn it, still allowed just tell them you had the carb rebuilt. New plugs and a clean carb! New air filter will get as much air in there as needed as well as new oil to possibly absorb some nasties or not burn old nasties. MAke sure coolant is up to par, a hot head is an NOx breeding ground but a cold motor is a HC adder as the fuel is not getting vaporized in the hot intake, it needs to be heated as designed. And vacuum leaks, VACUUM LEAKS on a carb will increase NOx as it will run lean and hot. Could possibly help HC but its a balancing act. PREMIUM fuel will cut NOx levels. I have a 92 SC400, 474 was NOx threshold, mine was like 531 on regular gas, it stated only use premium so what the heck, Ill try it. Next test on Premium (and a repaired brake booster line vacuum leak) lowere by NOx to 74!! NOw only my15mph low speed HC is failing (73 passing and Im at 99?) and I have new plugs...dirty injectors? Another vacuum leak YES, I found a purge control line off the intake to a switch was not connected. The EFI didnt meter this leak through the MAF and was compensating by increasing the duty cycle of the injectors to try and get stoich at the pre cat O2 sensor (maybe?) and was making the entire fuel curve richer than needed. I hope that is the case as cat's are $400 a piece and this car has 3 of them...and on is ticking on acceleration. I am sure it is damaged internally from a faulty coil last year. unburned fuel from half the cylinders for about 5 minutes of driving burning in the cats cant help things in there! All tests listed were after this incident. But I am very close to passing, I just have to get the HCs down another 24 ppm. 10 is average, 73 allowed, Im at 99. cold start injector sticking inside the manifold? Ill unplug the harness!
High hydrocarbons are from unburned fuel, or excessive burned oil. Plugs, wires. O2 sensors can help. High NOx is usually from lean burn issues.
tried to smog it again after I found the unplugged hose to the charcoal canister. Darn thing failed AGAIN and now the friggin HC are HIGHER (What the heck?) and the NOx is even LOWER at 35!!! Im thinking the vacuum leak actually helped dilute the HCs while slightly hurting the NOx levels but Im so low on NOx now that I may just let another vacuum leak ride in an attempt to get the HC under 73 or just say F it and register it in Arizona at my sisters address. Seems every exotic and motorhome in So. cal is out of state registered and for good reason. New Cal Cats are $$$, out of the question, Ill just sell it as a drift car.
Give it a tune up , cap rotor, plugs and check your plug wires, stay away from 93 octane and stick with 87 the lower the octane the cleaner it will burn, fresh oil and filter and install new air filter, if it's burning oil then a gal of lacquer thinner in the tank will help clean up the cat. ask me how I know.
yeah, wires spec out, new plugs rotors and caps, 2 new coils all within a year. oil and filter change before smog test...all the usual stuff. 93 octane (specified for this motor) lowered my NOx considerably so Im unwilling to go to better burning 87 (???) but I am willing to retard the timing 3 degrees max allowed in CA if 92 pre OBD2 Lexus allows me to manually? My fleet mechanic told me retarding will allow more time for combustion and hit up a smog shop just before closing to get him to do a gas analyzer pretest and then have him open a vacuum leak and see if it changes anything HC wise. I know my cats are shot. Probably an uphill climb with those not efficient anymore. Doesn't burn oil.
Hopefully Jaker04 got his car to pass emissions somewhere between February and now, since pishta is hijacking the thread with his '82 Mazda whatever.
I wonder if anyone has tried gas detectors like this
https://a.aliexpress.com/_mLV8UXQ
which might help measure the HC level before taking it to multiple tests
https://a.aliexpress.com/_mLV8UXQ
which might help measure the HC level before taking it to multiple tests
I have a common belt clip CO/HC/O2 gas meter for manhole work, it does ppm but only goes to 1000 ppm or .1%. CO is like 3% (30,000 ppm) on an '82 (here I go hijacking again) per the tune up portion of the FSM and .49% (4900 ppm) on a 92 SC400 per Cali smog. It does HC and NO in ppm--- CO, CO2 and O2 in % . HC, CO and NO are measured to a pass fail. So these little $80 gas meters could do HC and CO in ppm but not NO.
I'm passing real world info on a similar issue that can be useful to anyone reading this thread, thank you.
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