Help with emissions?

[Robertwav1]

Hello,

Flunked inspection here in NJ for Idle emissions, I think this may be something new as last years paper didn't have idle emissions. Anyway here's the readings,

Idle - Fail
HC ppm 304 (the standard is 220)
CO% 2.25 (the standard is 1.20)

High Idle passed at 39 for HC's and .07 for CO

What confuses me is that no codes (OBD1) which I understand has a lot less sensors the the OBD2. What do you do to reduce Idle emissions. I guess I'm a little spoiled with the OBD2 system which red flags everything and to me is easier to fix. This is a 93 ODB1 and don't know where to start??? I would take it somewhere if that's what I need to do. Any suggestions please would be appreciated. I rarely take the car anywhere to be worked on but I do have a corvette shop near by that has a good rep. Thanks

 

[boomdriver]

The OBD-II is not that different than the original. Its "onboard" vs off-board and the obd-II has a couple o2 sensors for better fuel control and to monitor whats going out the tip of the exhaust.

Your idle richness can come from worn dirty or tired fuel injectors, a tired cat, temp too low, dirty oil and emissions system...lots of things. OBD-II won;t tell you go here or there anymore than OBD-I will. All the diagnostics are designed to do is ID the system that has a malfunction, not what that malfunction is. If there is no code set, there is probably no malfunction. That indicates a cat or a dirty fuel/emissions system.
In the case of failing emissions testing with a car designed and produced 20 yrs ago.....the car needs a general tune up plus having some worn fuel system parts repaired or replaced...namely injectors. I know many guys that spent the $200 on new inj and got the result they were hoping for. Sometimes its more of a control issue, where sensors and adjustments are the key.
It would not hurt to go to your Corvette shop and get them to scan the motor and SEE what the ECM is seeing...then you will know what repairs are appropiate and whats a waste of time (and money).

Worst case...new injectors or/and a new cat(s) and a tune up

 

[Robertwav1]

I guess the best thing to do is take it for some diags. I would think the injectors are okay since I've sent them out a few years ago and have only put 3 or 4 thousand miles on the car since then. The cat is as old as the car. It runs so well I hate to have it touched but I guess it's time. 82K, I have changed the wires and plugs around 60K, at that time there was about .006 wear on the plugs. The oil is super clean as it gets changed once a year with around 1 to 2 thousand miles on it. So...off to the paramedics it goes. Thanks for posting!

 

[LLC5]

I guess the best thing to do is take it for some diags. I would think the injectors are okay since I've sent them out a few years ago and have only put 3 or 4 thousand miles on the car since then. The cat is as old as the car. It runs so well I hate to have it touched but I guess it's time. 82K, I have changed the wires and plugs around 60K, at that time there was about .006 wear on the plugs. The oil is super clean as it gets changed once a year with around 1 to 2 thousand miles on it. So...off to the paramedics it goes. Thanks for posting!

How far did you drive the vehicle before testing? The cat's need to be very hot to function properly, which is normally about a 20 minute drive with as many miles as possible on the freeway. Make sure that your throttle plate is clean of carbon build up, and that the PCV valve is clean and working properly. Good luck with it.

 

[Robertwav1]

How far did you drive the vehicle before testing? The cat's need to be very hot to function properly, which is normally about a 20 minute drive with as many miles as possible on the freeway. Make sure that your throttle plate is clean of carbon build up, and that the PCV valve is clean and working properly. Good luck with it.

Well, I don't think it's cause the cats weren't hot enough as this station I went too is further away and a longer drive then the one I used to go too which closed down. (They should all close down)...I will check the throttle plate and PCV which I haven't done. Thanks!

 

[Hib Halverson]

Looks like your engine is rich at idle but pretty clean otherwise.

It is likely, the reason you have no codes set is there is nothing going on with the system which would cause it to set a code.

The big difference between OBD and OBD II is that the former was only required to notify the driver a problem existed whereas OBD II was required to do that but also attempt to predict that there would be a problem. To do that, OBD II has more sensors and more diagnostic abilities, but...I digress.

I'd be looking for either misfire at idle or leaking fuel injectors.

Have you run the fuel pressure tests in the Factory Service Manual?

 

[Robertwav1]

Looks like your engine is rich at idle but pretty clean otherwise.

It is likely, the reason you have no codes set is there is nothing going on with the system which would cause it to set a code.

The big difference between OBD and OBD II is that the former was only required to notify the driver a problem existed whereas OBD II was required to do that but also attempt to predict that there would be a problem. To do that, OBD II has more sensors and more diagnostic abilities, but...I digress.

I'd be looking for either misfire at idle or leaking fuel injectors.

Have you run the fuel pressure tests in the Factory Service Manual?

As I have posted before fuel injectors were sent out and tested a few years ago and only 4 or 5 thousand miles on them. They weren't that bad when I sent them out but they blue printed and brought back up to specs. I replaced fuel pressure regulator a few years ago also. Oil is clean and the car runs great, like it did when I bought it. I made an appointment with a corvette shop close by so I'll see what they say. Like someone said here they will set it up on a computer and see what's going on. I don't have software for ODB only for ODB2 which is really very user friendly. Guess I should have bought a 94...... Oh well....I'll post results. Thanks All!

 

[John Robinson]

How much gas was in the tank when you went for the test and how old was it? You say the injectors were cleaned a few years ago and the car has not been driven over 4K miles. Makes me very suspicious that you have some old gas. Lets assume that you had a half tank of gas in the tank and it has been in storage for 4 or 5 months. That gas was evaporating all the good additives during that time. What that means is the gas has gone bad and even if you filled the tank up with ethyl you still have bad gas. You might try taking the car for a day long drive that will get the tank to were it needs 17 or 18 gallons of fuel and fill up with the highest octane gas you can. and then while it is hot and after you have driven 20 to 30 miles with the fresh fill go and have the test done again.

 

[Robertwav1]

How much gas was in the tank when you went for the test and how old was it? You say the injectors were cleaned a few years ago and the car has not been driven over 4K miles. Makes me very suspicious that you have some old gas. Lets assume that you had a half tank of gas in the tank and it has been in storage for 4 or 5 months. That gas was evaporating all the good additives during that time. What that means is the gas has gone bad and even if you filled the tank up with ethyl you still have bad gas. You might try taking the car for a day long drive that will get the tank to were it needs 17 or 18 gallons of fuel and fill up with the highest octane gas you can. and then while it is hot and after you have driven 20 to 30 miles with the fresh fill go and have the test done again.

Hey John,
I understand what your saying about the gas but my driving habits with this car have been pretty much the same over the last 10 years or so. I fueled up a few times this summer, a few trips to the shore and some local driving on nice days. Maybe beginning of summer the gas set for several months but I would think anything bad would be gone by now the closing of the driving season for me. It's a good point though. We have inspecton every two years and they changed the inspect procedures from two years ago. Now, stricter emission standards to get rid of older cars. They no longer do safety inspections to reduce the lines.

 

[Robertwav1]

Just an update, got the car back from the vett people and they replaced both O2's cause they were slow reacting as well as the cat on the left side was 200 degrees cooler then the one on the right. They told me that these cars for some reason have a tendency to go through cats on the driver side more then the passenger side. Emmissions checked out well after the O2's changed but they said the car should have passed easily. Possibly an O2 fading in and out could be the cause. They suggested to go through on a quiet day when not so many cars in line so as not to idle for a long time...strange how the back of the inspection sticker says "NO Idling" yet the very same state is making me sit in line idling away??? We'll see how it goes. The cat I let go as suggested to try it first without replacing. There quote price was 750.00 and 300.00 labor for the one side. The exhaust system has to be dropped and I would probably do both but would like to attempt it myself....can it be done with ramps and jacking up the rear of the car? I also see there are different types for my car, I was wondering if it's best to take a pic of what I have and replace with the same? Suggestions welcome. I have enough tools and still young enough to wrestle with it but I'm not sure of what it involves. Thanks for listening!

 

[kim]

Thats strange, everyone I know has had the passenger side cat blow out. I had mine replaced at a muffler shop with an aftermarket cat for $280.

 

[KANE]

Just my opinion... but I don't think too highly of the emission tests. Quite frankly, there are really too many variables to manage during what amounts to a snapshot in time. Bad equipment, cold vehicles, bad gas, operator error, etc. It seems to be more of an political thing than something that actually does anyone any good.:eyerole

Lots of folks have weighed in- and I agree with all of them. Back when I lived in NC, I found that taking my Vettes out and "exercising" them pretty hard a few days before an emissions test did wonders as LLC5 has stated. Your gas has likely changed in quality due to age (like John stated) and your root cause is beyond the monitoring capabilities of your ECM (as Hib has suggested).



Personally, I have an allergic reaction to spending money- especially when dealing with government.

Since you seem to be fairly close to passing, there are couple things that I would try before I spent several hundred dollars-

• fresh plugs
• air filter
• new gas
• run the heck out of it for 100 miles
• an "emissions passer" additive to give it just a little bit of help (scale it down for 1/4 of a tank or so)

The list above should be less than $100 and could get you a passing score.


Also- consider changing the shop who is doing the testing. I've had more than a few "fails" for that reason. Operator error happens.


Best of luck- hopefully Governor Christie will repeal some of the madness that applies to older cars and emissions as part of "spending cuts". :L

 

[boomdriver]

I was told by someone that WAS a smog inspector for many yrs that the test stations are typically the guilty ones and not the customer.

Its because they have to spend money (profits) to maintain the test equipment and they dont, and that the equipment is calibrated to an exact specification. When thats not correct becasue of old dirty filters and pick-up nozzels that are caked with carbon and soot the test machines will start to fail every vehicle that rolls thru the doors. Thats when they will finally do the maint, but only after they've passed out a pile of FAILED test that are all registered with the state.THEN some clearisil tester will stop the show for an hour and do the maint on the test equipment thats supposed to be done daily. One hr of downtime on the equip equals 3 to 4 test that they are not putting in the cash register.

The proper proceedure is to replace certain filters EACH morning before any testing is done. Calibrate the machine to meet the conditions, humidity, temps and do so with clean and fresh parts. They don't do that because it cost money and what do they care if you fail....they often get to do some BS repair or get to do the 2nd or 3rd test from another station and charge you for it. I've personally had to buy a new gas-cap from the test station before they'd pass my car...and I KNOW it was bunk 'cause that "failed" cap was only a few weeks old. ad

The gov has the right idea, just the wrong approach. You can't mandate testing and be fair with the results if you sub contract the work to an entity (privately owned and operated stations) that can potentially profit off of the result....either way. Thats why many states do not allow test stations to do ANY type of repair work. Too much opportunity for crooked station personel to manipulate the result for their gain.

 

[Robertwav1]

Well, I guess this thread is finished now. I Passed this morning . The only thing that was done were the O2 sensors which the cars computer failed to recognize as going bad. Had it been an OBD2 system with the added O2's on the downstream an error would have occured and I would have been able to correct it. In this case the O2's had to be checked seperately and yes they were functioning but slow to react. Another lesson learned, the newer stuff is easier because of the updated computer in the cars. So, don't let you O2's go to long...