I can't believe I have failed 5 times. Evertime on Hydrocarbons. I think I'v read most of the message boards about emission failures and tried just about everything. Standard for HC is .80, the closest I came was .98. The car is a 92 RS, 305TBI with 125,000 miles. I have replaced everthing. Complete tune-up (plugs, wires, coil, cap and rotor, oil, air filter). Other items. Converter was replaced about 9 months ago, O2 sensor 1 week, EGR about 9 months, smog pump 1 week, 1 bottle of guarentee to pass (crap). The engine is stock except for flowmaster muffler. The highest reading was 2.80 the lowest was .98 on HC. I have run out of things to try. The engine runs good and strong. Any suggestions would be welcome at this point. Also changed thermostat (190), and did finally get my electric fan to come on.

 

The complete results for the last three tests, type of gas used, timing setting and changes from test to test. Without this info, no one can tell you anything more than you've told us.

 

By test results if you are refering to the graph they give you I don't have a scanner. The last three results were .98 then 1.03 then today 2.30. Really don't understand the last test results. I'm using 89 octang fuel and I have not played with the timing. It is set to factory specs. Also I am letting the car get warmed up to proper operating temp before testing. I got the .98 by replacing the K&N filter (new by the way) with a FRAM filter. Hope that helps.

 

No, I mean HC, CO, CO2, NOx, O2 and anything else they give you. Also, is it a dyno test, if so are you failing load or idle? Is your AIR pump working and connected properly?

 

Sorry, My CO was 12.10 (standard is 15.00) and my NOx was 1.90 (standard is 2.50). The keep the other results when you retest so I don't have them. But they mainly stayed about the same. Only failed on HC. Its a IM93 test were they drive it on a treadmill, verying the speed.

 

Airpump is connected and working.

 

Test your CTS, bump up your timing, go to a step colder plug, go to 87 and lots o' alchohol and really, really check your timing. It really helps to see the last few total results to see any trend in your tests. You may be running rich and/or your timing is off.

 

A very simple way to pass is to put a gallon of methanol into the tank with 3 gallons of high octane gas.. I failed the first time with 3x over the limit on HC, and also failed on all the other three. I didn't know my injector was toast at the time, so just used this trick. I did not pass but just by doing the above, I was only 1.1x over, which is a HUGE improvement. My car died a week later and I found out my injectors were toast. After replacing four of them and a tuneup, I passed with flying colors with methanol after failing by a very small margin without.

 

maybe something small and rather insignificant..but..

try getting a new gas cap..may not be pressurizing properly..

iroc2nv

 

Part of the test is to pressure test the gas cap, and it always passes. I'm going to have the temp tested at the CAT to make sure it is getting hot enough. I'm just at a loss of why I keep failing.

 

Checking the Coolant Temp Sensor is a good idea like was mentioned earlier, also verify the timing is set correctly. Also, drive it around for at least 30-40 minutes before going to the tester and don't turn the car off while waiting for your turn on the dyno. The cats have to be HOT to work at their best efficiency. Good Luck!!!!

 

CTS was replaced, and the timing is set to factory specs. I also drive to the emission test faclity in the next town, about 10 miles.

 

A new pcv valve and filter wont hurt any. Theyre both usually very cheap and both are possible causes of failure.

 

Did that also. When I tuned it up, I tuned it up. Everything. Every sensor, every wire that can be replaced (vacume also). I had my new converter tested today and he said its not getting hot enough to burn off the hydrocarbons. He used a heatgun pointed at it. It showed 200 temp in and 200 temp out. He said it should be hotter going out. Can anyone here confirm that? Thanks for all the help and comments so far. Scott.

 

you carbed or fi?

what about ur fuel sending mechanism..

fuel rail for fi and carb for carbed?

iroc2nv

 

Note the timing part. It may look right with the gun, but it's been mentioned a time or two that certain timing tabs on these cars are, shall we say, not known for reliability. Also, if that 200º is F, then no that's not right.

 

its possible you have a bad converter, what brand is it? if just your hc is high, it sounds like a lean miss. Check for vacum leaks. is it rough at idle? you may have a bad plug (internally shorted) or a bad wire. Spray carb cleaner around the intake and listen carefully for any detectable change in idle. As a "jackass test" try to restrict your aircleaner to see if the hc drops, that is a sure sign of lean miss. Another thought is your map sensor, it might be going south. Also, just a thought, disconnect your brake booster and plug the line (do not drive this way!)see if your idle vacum increases.

 

maybe you missed my post.. you're only over by a little bit.. a 4 to 1 ratio regular gas to methanol (you can get methanol for the same price per gallon as gas at any mechanic shop) will lower your emissions by at least half, and most likely more (in my case, it lowered my emissions by 70%, although it still wasn't enough to pass, my injector was toast). Of course this is a temporary solution, so if you're worried about the health of people around your car (really, it makes little difference with inderect exposure) and the proper functionality of your car, I guess this is not an option for you.

Other then that I can tell you from my experience its either the cats (unlikely, the stock cats are good for lots of miles, at least for emission purposes), or like in my case, used injectors not pumping the proper amount of fuel into the engine. in my case, it was only 1 injector that was faulty, and it put my numbers through the roof, HC was over 5x the allowed value.

 

My car has the TBI on it. While never tested, everything appears to be working. I did add a 1 inch spacer to it. Cleaned the TBI and replaced some of the parts on it, not injectors though. Timing marks off could be a problem, but how would I know? Do not know the brand of the the converter, it was put on by a good muffler shop. And you it was 200º F at both ends.

 

I'd suggest a new cat. Quick and cheap. Usually fixes the problem. Just because something is new, doesn't necessarily mean it's doing its job.

I think this is the one you need, but I don't mess around with anything to do with TBI motors, so I don't know for sure.

http://store.summitracing.com/partde...?part=CTO-4115

 

 

Trypt, how would that fix his underlying problem? I would want to try and fix the problem not mask it entirely.

 

It would make him pass the emission test, thats all.. failing does not do anything to performance, so really it is not a problem.. if the cats are bad, just throw the suckers away. If the car stinks, then of course he'll have to do something, i hate driving behind stinky cars, i hold my breath. And if it is a serious problem like a faulty injector, then for sure he has to change that since the whole engine would be running horrible in that case.. But if everything is fine and its just a few extra particles getting throught the cat, methanol is a cheap way.

 

The engine runs fine. I keep the oil change and the engine tuned. When something is wrong I fix it. There is no reason why the car should have failed 5 times. Right now, I just want to pass and forget about this for another 2 years.

 

My HC's have to be 220 or lower and every time i'm over 800, so before i put gas in my car i buy 1/2 gallon isopropyl alch. pour it in then fill up. sometime it runs a little rough so i drive it atleast 100mi. and my HC's last time were 12. you might also find a local shop that has an exhast gas analyzer and just move your timing around till its in specs. drive to the test site, pass, then back to the shop and change the timing back to make it run right. Another thing you might try is running the highest octane gas you can buy, my dad does this for a month before he gets tested. don't know what it does he's just always done it.

my .02

 

Man, just move to another state with no Emissions checks, i could run a carberated 540 down here in KS, no cats, no nothing, they would never know or care. Heck, my truck is completely free of all emissions equipment. But hey, I guess it is a 72, and therefore outta the federal mandate.

 

i test cats 2 ways. with the car already warmed up & my exhaust analyzer in the tail pipe i run it around 2500 rpm for about a minute or 2 & then shut it off & quickly disable the ignition, i then crank it over & watch the co2 reading on the analyzer, i like to see it go to at least 5 percent, the higher the better. next i do another 2500 rpm run & then raise it on the rack & check the temps, on a good running motor with no problems i want to see at-least 100 degrees hotter on the exit side than the inlet side. if either one of these doesn't look good then it needs a new cat, you said yours had the same temp inlet & outlet, if it was tested
right then your cat is dead.
when buying a new cat, beware, all cats are not equal, i have seen some replaced because of a HC failure, after replacement they passed HC fine but fail on Nox.