I failed emissions again on hydrocarbons. Very close this time. Will a new converter help with hydrocarbons? I turned my timing back to 4 degrees base. I unplugged my primary fan so the the temp would be about 230 (I have a 160 stat with a hypertech chip). I dont know what else to do. I just replaced head gaskets and all electrical items.I even tried a can of guarenteed to pass. No codes on scan tool. HELP!!!!!!!!!!!!!!!!

 

If the cat has never been replaced and you've taken care of all of the less expensive things, I'd say replacing it is a really good idea. The new one I got three years ago went bad after two and a half years.

 

what converter do you recomend??

 

Well, hydrocarbons means unburnt fuel, so what electrical peices did you replace? Do you have fresh spark plugs? Good wires? A good coil? A fresh converter might help burn off the extra fuel, but it might just be cheaper to give it a tune up, and an oil change, and see if it passes.

Well, there is an idea. It always works up here in Jersey.

Joker

 

Do you run a idle type sniffer test or is it run on dyno rollers? Does your car basically run good? If not, do the tune up thing. If your CO is low & your HC is constantly high, & you run the dyno roller test whereby the sensor probes go around the tailpipes instead of sticking inside the pipes, reply back. I think I might know the problem.

 

I already did all of those things with the exception of the new coil.

 

the treadmill is what they use with the pipe that fits around the tailpipes while testing. The HC are high when at low speed but get low as the car speeds up.

 

By the way the car runs great. No Problems!!

 

Reason I'm asking, I fought this HC problem on my son's 88 GTA for 3 weeks. The problem was a leaking filler neck where it enters the fuel tank. Not a liquid leak, just fumes. Our first test almost passed, we were low on the 2nd accelleration run. However we started into 95 degree days & the car was steady high HC. To find the problem, I had a friend with a 4 gas anaylyzer probe the system. In the tailpipe, HC was 20 ppm, probing the filler neck to tank, HC were 1500+ ppm. We dropped the tank & resoldered the filler neck. The day I had my friend check my car, he had another 88 GTA for the same problem, won't pass HC. We found the same problem on that car. Since the guy could not afford to have the tank repaired, my friend offered the following suggestions. Wash down the filler neck area with soap & water. Run the tank low on fuel. Leave the gas cap loose before getting to the test station. Carry a couple of gallons of water & wash down the filler neck just before going in for test. Go on a cool day.
BTW, on my car, yeah, you could smell fuel when you opened the filler neck DOOR and with the gas cap in place.

 

I will check this. I smell gas around my car at all times and could never figure it out.

 

The testing station pressure tests the gas tank b4 testing for emissions. I do appreciate your help and i will check this out.

 

Test the tank? Are you sure? In Illinois, they check the cap. BTW, I trryed retarding timing & high coolant temps as well & still failed. As I said, is your CO low? The CAT lowers both CO & HC, so if your CO is low, I doubt it's the CAT.

 

Sounds like theres a small vacuum leak causing high HC down low where theres high manifold vacuum aiding in the leak.

 

Emissions tests only test the cap usually, not the tank. I had a leak in my system from the cap due to a small dent on the filler. Wouldn't seat properly and wouldn't pressurize. Some creative sanding and voila a fully pressurized system and a very low hc count. When you take the gas cap off after a hot long run, do you hear the pressure release? It's very loud and unmistakable if you don't and smell fuel when sniffing around the car with the cap tight, odds are you have a fuel leak somewhere. When the system isn't pressurized, it takes a lot more fuel flow to bring up the pressure for the injectors which causes a rich condition and almost always guarantees a fail in the HC department.

If you've changed plugs, cap, rotor, wires and still have a high hc count, the next thing I'd go after is a fuel leak. A cat is good for getting rid of unburnt hc, but you'd rather have your engine burning it for you rather than relying on the cat. I'd only change the cat if I knew the rest of the system is at its peak condition.

 

I agree with much of what has been suggested.

Vacuum leak should tend to lean out the mixture moreso at idle. Almost positive of this with mass air. With speed density a vacuum leak creates an artificially high manifold pressure (low vacuum) hence the computer sees a load that isn't there and adds more fuel than is needed. The lean condition with mass air could create a lean miss fire at idle that might send just enough unburned fuel into the exhaust through a slowed down burn and or just plain bad combustion, to spike the HC low and then have it clear up high when the leak would be a much smaller proportion of the total amount of air going into the engine. Someone(s) really familiar check my logic on the mass air-speed density comparison.

I too have an 88 GTA with the crack in the tank where the filler neck met the tank. It has been welded, SOMETHING YOU WANT DONE BY A PROFESSIONAL WITH THE TANK OFF THE CAR AND ABSOLUTELY CLEAR OF ALL FUEL FUMES.

If it's lean at idle (vacuum leak)with mass air, less timing shouldn't help, it should hurt. Has the HC dropped as you've backed off timing, or did you only change ignition timing once?

I agree with the high coolant temp concept. I have also heard from technicians who agree with the high coolant temp, but also believe as has been alluded in this thread, that lower air temperature is better for passing emmisions. Not sure why this is, because hot air is generally good for combustion efficiency as long as it is not contributing to preignition or detonation.

You have to be careful with this next concept, but you may want to try adding methanol/ethanol to your fuel. If I were doing it with you vehicle, I would get the tank near empty and add no more than a half gallon of alky, and then add 6-8 gallons of premium pump gas. I wouldn't let the system sit this way indefinitely. I would set up the fuel this way, drive the car 10-20 miles a then do the test. Immdediately after the test, if you passed, fill up with whatever pump gas you want and drive off into the sunset. If you didn't pass but saw some improvement you might try adding a little more alky like 1-2 qts, mix it up by driving with it in the tank, and try the test again. It's not a good idea to let fuel systems that were not designed for alky, to be exposed to it, especially in higher concentrations, any longer than necessary for the purposed of the test you are doing.


Good luck. Let is know how it turns out. Post some actual emmissions numbers from your tests.

Chris

 

First test:
HC 2.68 GPM Standard: 1.7 GPM
CO 12.22 " 30 "
NOX 1.45 " 2.7
CO2 N/A

Second Test "
HC 1.98 "
CO 8.59 "
NOX .812 "


AS YOU CAN SEE ALL OF THE NUMBERS WENT DOWN. IT WAS ABOUT 10 DEGREE COOLER ON THE SECOND TEST WITH TIMING AT 4 DEGREES BASE AND COOLANT AT ABOUT 230.
WHERE CAN I FIND ALCOHOL TO ADD TO TANK. I HAVE BEEN TOLD TO USE DRY GAS AS WELL (WHICH IS ALCOHOL)
THANKS FOR ALL OF THE HELP!!!
I'M GOING TO LOOK FOR LEAK AT TANK THEN TRY ALCOHOL TO GET THESE MARYLAND COMMIES OFF MY BACK.

 

BY THE WAY I CHECKED FOR VACUUM LEAKS. I CANT FIND ANY. I SPRAYED CARB CLEANER (CAR RUNNING OBVIOUSLY) ALL AROUND INTAKE TUNED PORT RUNNERS, CHECKED LINES, NO LEAK I CAN FIND.

 

I had to pass a 0.8 gram per mile standard & we were anywhere from a 0.92 to a 2.6. Your CO number doesn't quite make sense to me 12 something...against what standard? We even tried 30% methanol, which made the problem worse, it has a higher vapor pressure. I don'nt think a can of alcohol is going to help you. Try testing on a cool day & the filler neck cleansing process. Good luck.

PS Keep the timing retarded.

 

Lean out the carb
If you fail on hydrocarbons like joker37 said not all the fuel is getting burnt. I had the same problem but in a more harsh situation.
Anyway in my case the car was running extremely rich. All they did was lean out my carb (I think) and I passed. $99 for the dynostics and tuning at Canadian Tire.

 

THE MUMBERS I POSTED WHERE THE ACTUAL EMISSION AND THE SECOND # WAS THE STANDARD. when i typed it up it looked good> when the message posted it moved my quote marks>

 

FJK help the guy out with how you got your alcohol. I was going to suggest contacing VP race fuel vpracingfuels.com.

Some gas stations have methanol pumps. There is one within a mile of my home in SoCal but it requires a card to operate and looks kind of lonely. My guess is one needs to own or have legal use of a flexible fuel vehicle to get one of these cards. Anyone with experiene in this regard?

My guess is 30% methanol was too much. From my suggestions you can see I think somewhere in the 3-10 maybe 15% range is good to try, but too much would be detrimental. There may also be O2 sensor related issues with an injected vehicle vs an non feedback sytem many carburated systems.

Can you post your emmission numbers with and without the 30% methanol and list any other changes made in conunction?

I am not doubting you, but explain why you think vapor pressure characteristics of the methanol were the problem.

 

Cristobal: We're talking about 2 completely different things here. You're thinking about this methanol thing as it affects combustion and its resultant effect on exhaust gas emissions. In which case, you are correct. I'm talking about exhaust gas emissions that are perfectly acceptable to pass an emission test, but the test station sampling probes also pickup ambient air around the tailpipes that have gasoline fumes being emitted by a leaking filler neck to tank seal. That is why the higher vapor pressure of ethanol & hot days cause HC to go up. Gasoline fumes are under a higher pressure & can escape the filler neck crack more easily.

I can't comment on the source for the methanol because my kid got it from my friend' s business. Since this guy has alot of racing contacts, I assume he probably purchased some from a race fuel source, like VP or Elf.

 

FJK

I understand what you mean, I just wasn't sure of the entirety of what you meant as far as the alky is concerned.

I would still be interested in what your numbers were.

Chris

 

Chris: My numbers have no meaning because they were being corrupted by the fumes by the fuel tank. In fact, when the car ran methanol, we also had 2 injectors unplugged & we set our world's record for HC's, about a 2.8 as I remember. I think we ran the test 5 times before we passed. In Illinois you get 3 chances to pass. After the second failure, I bought 2 voluntary tests because I did not want to go for a waiver. The car has a Vortec supercharger and for all but 1 of the tests, we had the supercharger drive belt removed. With the fuel tank repaired, I believe we could have passed with the supercharger operating. Howerver, for the last test, 2 things were changed at once. We fixed the tank, but we also had a new CAT installled. For all tests, the CO was really low, indicating to me that the CAT was ok. On the final test, the car "fast passed". CO was non-existant (0.009 g/m)and HC were 0.039 g/m. We also had timing retarded on the last test, 0 deg btdc.

 

Gotcha

Thanks

 

FJK: I am thinking of doing a engine swap to a 350 from 305. What emmision pieces can I leave off in Illinois an still pass, that you know of? Or do I need everything back on? Thanks

 

86
You need whatever emissions componets to pass the test. Meaning, the car is not really scrutinized for emission related componets, the car is just tested. If it passes, it passes. If it flunks, it flunks. They also check the gas cap, which has to pass a pressure test. What does this mean from a practical standpoint? I would say you definitely need the CAT & the air pump functioning. Doing an engine swap with an electronically controled engine, it is almost easier to retain all emission control devices from a donner car, than is to eliminate them. The problem comes in if you flunk emissions & want to apply for waiver. That is when they will check your car for emissions componets & tampering. There are a number of conditions that have to be met to get the waiver. Some of these are:
1) Your final test you flunked must have shown an improvement in emissions compared to the earlier tests you flunked.
2) For 1981 (I think) & newer cars you must prove with receipts that at least $500 has ben spent to improve emissions AND the work was done by a professional tech (not yourself).
3) They inspect the car to see that all emission related components exist and have not been tamper with.
4) The engine is not modified, they use the example of adding a turbocharger.
So, if you do the swap, you really want to be able to pass emissions & not get involved with the waiver runaround.

 

I would say it definitely pays to suck it up and temporarily install a stock sh!tty cat like Walker/Dynomax ($90-$100). Seeing your CO it seems that the exhaust output is not that low.

Check out how I fixed my emissions problems .

With a brand-new cat your CO is supposed to be super-low. Before putting a new cat, changing the plugs, air-cleaner, etc. I polutted more than a diesel truck. (Again, check that link out) After those changes, I passed in 30 seconds, like a brand new car.

Your HCs are suspiciously high, but your CO should be close to 0 , or between 0 and 1. I'd say, put a brand-new stock cat (get it welded for $30 or so if you use a wider exhaust) and pay $20 for a voluntary test. After you pass the voluntary, just come back in the line and do it again, officialy.

I have a manual fan switch setup. I turned the fan off on voluntary and the car overheated. I passed, but I had some NOx's (caused by higher temps), still well within the legal range. The next time I had it running all the time -- it was a hot day and my car's temp didn't go below 185, didn't go much more above it either. All the results were pretty much the same, except I had 0 NOx's.. (it said N/A on the report).

I live in Illinois and I think we have the same test...

 

Oh, yeah, I think 0btdc is way too retarded for idle. It's going to make you run rich b/c the combustion is so inefficient.

 

I've got a Turbo TA and am fighting the same problem; high HC, normal CO.
I am beginning to suspect false readings from the fuel tank as well. I do know that the last owner dropped the tank to install an upgraded fuel pump, however I do not smell gas, and I do hear the pressure hiss out when I open the gas cap.
The car's original cat had been gutted, which I did not know. I went for a test, and failed with 3.6 HC, 14.2 CO, and 305.5 CO2. (This is GPM on an Illinois IM240.) I swapped on a known good cat from a friend's car, and did the other usual tune-up items, and failed again. This time with 1.7 HC, 6.4 CO, and 399.4 CO2.

FJK -- Was your tank still pressurizing with the leak? I can hear mine hiss as I remove the gas cap. And whereabouts in IL are you located? I'm in the NW burbs and am thinking that your friend with the 5gas analyzer could be a big help.

 

ALXTTA 1
Yes, my tank would still pressurize as you described. That's what initally drove me away from thinking it was the tank filler neck. Also, it was a mental thing, pulling the tank & then discovering that it was not the problem. That's why I wanted some evidence that the filler neck was the problem. I'm not trying to talk you into it or out of it. I will give you this information to help make a decision. Look at you HC plot (trace) that they gave you when you failed the test. The trace will undoubtedly have some minor peaks & valleys, but if the entire trace runs above the dashed line standard, it could be the filler neck. The fumes from a leaking filler neck is a constant throughout the test cycle & offsets the HC's above the standard. If the HC has dramatic spikes & valleys in different portions of the cycle, chances are it is something engine related. Also, compare the peaks & valleys of the HC trace to the P&V of the CO trace. Do they follow one another? If so, it again would be more engine related.

My friend's shop is in the western suburbs, Glen Ellyn. The place is always busy, so I'm sure you would have to leave your car for a couple of days, just to get it diagnosed. Chances are many shops in your area have the same capability with a gas analyzer.

Regards, FJK

 

FJK - Thanks for the quick reply.

In the beginning of the test, 2 of the HC spikes are worse than with the gutted converter (near 7)! Once the veh speed reaches 45-50+, then the HC hugs the limit line (although it barely ever goes under.) The HC trace does not seem to follow the CO trace. Actually, at a few of the worst HC spikes, CO is near zero.

I can email pics of the traces. I'm thinking maybe the cat wasn't fully lighting off at first, and this coupled with a small fuel leak, causing say, .5 constant false HC, is the culprit. What are your thoughts?

 

my car had a 2.8l v6 (carbed) with nothing but fresh plugs, converter and exhuast
CO: 14.020 out of 14.808
CO2: 284.600
HC: 0.998 out of 1.445

sombody explain the high CO's

 

Alxtta 1: Either post or e-mail (private message) the traces after your last test that had the better cat.

Redcamar83: High CO's, sounds like you are running too rich.

I'll try to help you guys out, but I'm no emissions tech. I just play one on this board (LOL).

I just ran my 92 Ford van through today & fast passed. As you could see with my earlier post on the 88 gta, it also fast passed, which means emissions numbers really need to be low. On a fuel injected car I would think with a resonable tune up, an active CAT, & an operating air pump, it would be difficult to fail.

 

i had the same probleum and a new o2 sensor fixed that. that and use gas octane treatmentin your gas tank. and drive around the expressways just before you go for the test. that will help!

 

FJK - Here's the latest trace. Any advice appreciated.

I was talking to a guy in CA and he found one issue. Normally, I run my car with a breather on the driver's side valve cover. For the testing, I'd been replacing it with the stock oil cap. By doing this, I had basically blocked any vent for the PCV. He thought this might be a problem and suggested I run with the breather.

 

2 things:

what do you mean, the tank was pressurized?? if anything there would be a slight vacum.

secondly, low CO and high HC would indicate a lean miss. The car misfires because the mixture is lean, resulting in unburned hydrocarbons, High HC

 

ALX:
In looking at your traces, it seems to me that you have some fundamental engine problems & not a fuel tank leaking problem. You said you did a basic tune-up, but did that cover all aspects of the ignition system, plugs, cap, rotor, ignition wires? Although your CO passes, it is still not that clean. Here is what I would be looking at:

For HC's:
Ignition system tune up as stated above.
Air pump system;pump working, divertor valve working, no leaks on plumbing.
Ignition Timing Set Correctly
Fuel Pressure Regulator vaccum line correctly connected to intake maniflod.
Turbo boost leaks

For CO's:
Replace O2 sensor if more than 50K miles (might affect HC as well)

Both HC & CO
New CAT

 

Hmmm, thanks. The Turbo TA has a DIS (distributor-less) ignition system. There is no cap or rotor, there is a coilpack. I need to check that. I did replace the plugs, and the wires seem to be good, although I still need to check their resistance.
There is also no AIR system, as far as I know. There is no pipe for it on the cat. Timing is set within the chip. The fuel pressure looks fine (I have a gauge for it on the A-pillar.)
The 02 sensor is a brand new, stock replacement.

I really hate to just start replacing other parts, ***** nilly. I need to find a mechanic close by that I can trust to truly diagnose the problem.