I just had this problem with my 95 Tahoe. It passed emissions fine 2 years ago but when it came due this year it failed miserably. First the testing facility made me install a new muffler and tailpipe sinc ethey found a leak, then I figured I'd clean the plugs and do basic tuneup stuff and the HCs were WAY high. My brother-in-law the Chevy mechanic took it into the shop and retarded the timing and took it back to get it tested. It failed by .02 points. So we replaced the catalytic converter and at the retest it passed better than it would have rolling off the line. He set the timing back to stock after the retest. It seems the culprit was a bad catalytic converter. You need to know if it's the HC's, NOx or CO that's out of whack so you know what to focus on when you try and repair the system. My buddy had a 79 Monte Carlo with a well built 350 that only had dual high-flow cats on it for emissions equipment and he had to retard the timing WAY low in order to pass emissions but it passed.
In wisconsin to get a collector plate my buick had to get tested, this was when I first got the car and had no idea about anything car related. I was happy when the people at the test station said that that the car had just a trace, and that the newer cars dont run that clean. Now that it passed and I got my plates, I decided to start replacing parts on the car. lo and behold, I get underneath the car and see the big holes rusted in the tail pipes!:laugh:
I have always run the car hard to get it nice and hot, made sure I had just enough gas to get to a station after the test, and dumped a bottle if isopropel in the tank
If it failed because it had high HC/CO levels you can dissconect a small vacum hose (introduce a small vac leak) to lean it out at idle. To much of a vac leak and your CO will be fine, but the HC will be too high This also means that if your CO-levels are ok, but HC-levels are too high during a test and you didn't pull any hoses, you probably already have a vacuum leak somewhere... You may be able to lower HC levels by altering the timing.
:Brow: Hypothetically speaking, you should be able to buy a gallon of ethanol alcohol (not isopropyl) from a local chemical supply store. You can add this to your fuel tank (1/8 or 1/16 full) to get a 15% to 20% alcohol to gas mix before the emissions test and run the car at higher speeds to get the engine nice and warm, then pull it in for the emissions test. As soon as the test is over, fill the rest of the tank with gas to dillute the remaining alcohol and burn it out. Hypothetically speaking - if you know what I mean - non-California emission vehicles used to pass the California standards for emission .... all the time using this process.:Smarty:
Looks like I failed :blast: They no longer use the dyno test. I was thinking maybe that would be a better test with the dyno for my 80's car. I used the seafoam and it was running great. I changed the plugs and the car started running bad. It is kind of like a hesitation and the car bucks while I am trying to slow down. It feels like I don't have enough octane or clogged injector. The car has done this in the past and I always put injection cleaner in. I was thinking about opening the spark plug gap a little bit. I checked the plugs before I put them in and they were around .38. I believe I had the old plugs were around .40. I will pick up some more injector cleaner and try that. I did not check the timing. So that will another thing to check. I have till the end of next month to pass. I will have to work on it when I get back from Carlisle. My CO reading was 1.65 and the standard is 1.20. . My HC ppm reading was 211 and the standard is 220
seafoam generally will make the car run worse for a while as all the sludge gets broken up and passed through the system. Make sure you do an oil change too after all that crap gets passed through. Here they changed the test to plug in on obd2 and check for smoke on '95 and older cars. Alot better than the old dyno days where certain places would screw you for repairs that weren't needed. I have a buddy that does inspections and he said most of the cars fail because the inspection station doesn't clean the filters in the machine. It causes a bit of a backpressure which makes the machine read stagnent air. Almost like a big EGR setup.
I already dumped the oil that had the seafoam mixed. I might have had around a quarter tank full of gas that was mixed with the seafoam after the oil change. I added $20 which is about 5 gallons of gas. I am going to buy a different fuel cleaner to help it run better. In the past I have been able to calm the car down from bucking this way. Let me take a ride. Thanks, Rob
I was thinking about that before some. I used ac delco R45TS and 45TS. I had some of these plugs in the garage already and I could only come up with 4 R45TS and 2 45TS. I believe one of the 45TS plugs were shorter because it was an older version. I was not sure if I could mix them or not and I thought the R stood for resistance and that was for radio noise only. Looks like that might be the problem :spank: At this point I am ready to start all over with the tune up and replace everything. What kind of plugs should I buy??? What Brand Distributor Cap and rotor should I buy? I believe the wires only have 2,000 miles on them. Thanks, Rob
As far as the CO, how old is the O2 sensor? HC's are affected by tune up parts- plugs, cap, rotor, wires. Also change the oil and filter right before the re-test
Not sure the age of the sensor. I have had the car for 7 years and never changed it. The service engine light has come on and off a bunch of times. I did jump the number one and # two pins on the testing port and came up with one flash and one flash for the #11. Not sure what that number means. The chart I found on-line did not mention that number. Maybe I was doing it wrong or it just was not listed. I will add the O2 sensor to the list. Thanks, Rob
I have all the GM Exper-tech books for your year car. If I remember correctly (its been a while since I fixed an OBD 1), Its supposed to flash a code 12 first, then flash the fault code or codes, them finish the sequence with a code 12 again. Then start all over. We need to find out exactly what code we have in there first before we start just throwing parts at it
Jason, I believe the codes are 12, 12, 12, 44, 44, 44, and it went back to 12. If you have any info please let me know :TU: Thanks, Rob
No longer- the new units are sealed and state certified ( at least in Caliphonia ) . Best bet? hypothetically speaking of course- slip the guy testing a a bill and let him run the Honda thats in for a brake job on your test...:bla:
Code 44 is "lean exhaust detected". An oxygen sensor curcuit. Good guess right? :laugh: Here is the information I have on what you should check-
:gp: For futre reference code 12 tells you that the connection is good and that you are comunicating with the ecm. The trouble codes will follow after 12 and then after all of them are shown it'll go back to 12. Every code is flashed 3 times to make sure you don't misread any. You only have 1 code and it's code 44
I've also heard, (don't know how true it is), that if you run the car hard before the emissions test and get the catalytic converters nice and hot, you have a better chance of passing. You're lucky. I went through all kinds of hell trying to get a Chevy powered Suzuki Samurai to pass. Most places wouldn't even touch it because of the engine swap. Eventually I found a place that would. They checked emissions on one exhaust pipe (true duals, no cats, only mufflers), so actually, they only tested 3 cylinders, and it passed.
