So here I was waiting in line to get my 1990 GTA 305 Aircared, thinking to myself "with my luck I'm not going to pass this stupid emmisions test". Low and behold I didnt. My hydrocarbon levels at 40kph were twice the maximum allowable (155ppm/80ppm)!! At idle they were fine though. I replaced my O2 sensor about a week ago when I did my routine maintenance but damn! I am wondering if anyone else has had this problem recently. The only two things that I can see them having a problem with is that my valve seals do leak a tad, so I puff a bit of smoke at startup but they never saw that. Possibly my Cat is so old that is is not working properly? Are there any other Things that I should check? Thanks...

 

First off Welcome aboard!!!

Second - what area do you live in, is there a visual inspection, judging by the fact you said 40 KPH I assume you live up here in the north.

Also how many miles do your car have?
When did it last get a tune-up? Plug/wire/cap/rotor/O2 sensor.
Are there any SES codes?

Make sure your car was in it's operating temperature as well.

 

Yeah I live in the greater vancouver area. I replace my stock plugs, wires, cap, rotor, and coil maybe 3 months ago. I put a MSD coil and wires on, Accel cap and rotor. Cant remember which plugs I used but from what I can gather it doesnt much matter. I replace the O2 sensor 4 days ago.
There was a visual inspection, and like I thought there were no problems. My stock cat is still on there.
The car has 125,000km on it, and I havent really had any ses problems, except for once. It was an odd experience, I was on a road trip, nothing felt wrong with the car and I was getting extraordinarily good gas mileage. It turned on when I was nearing the end of the trip and then went out the next day.
I am going to try and pull any codes up if I can here soon this weekend.
The car was as warm as I can get it (roughly 90C) when i pulled in, I was driving it for about an hour steady before hand.
Oh and one more thing that I can think of is that my timing may be off, when I got it done they said it was set to 8* which seems a little bit high, though I run 89 or 92 octane most the time. Ill have to check that too when I get a timing light.

 

Make sure your timing is at 6* also run 94 octane.

Check for any vacuum leaks, and definately pull the codes.

High HC's is a rich condition normally, I would check to make sure your IAC and TPS are adjusted, check all your sensors.

Do you have a colder T-stat?
Aftermarket chip?

 

I've always had good success adding (a LITTLE) Methyl Hydrate with 94 Octane Mohawk gas.

Consider yourselves lucky. I have to wait at least 30-45mins for my Aircare tests. I have a 92 Camaro, so it's subject to the new kind of testing where they simulate different rpm ranges through different gears. Anyways, my first time through (after the cam/head/intake swap), 4 different Aircare attendants had to drive my car, because they couldn't keep it within acceptable limits. THEN, they had to switch to the 4WD dyno, because they couldn't keep the rear wheels on the 2WD dyno.

Needless to say, that their incompetence/inaccuracies had me coming back every weekend for about a month because i kept failing at the border line. I made it a point to rip through the side lane (before you make the turn into the lineup) to announce my arrival. Some of the guys would even come out and chat with me for a few minutes.. yea.. I got to know those guys pretty good after a while.

 

What kind of Cam/head you running?

 

zz4 cam and the holley systemaxII heads... I'm sure it just needed some prom tuning for aircare.

 

Schwem, that wouldn't be red with t-tops/ 5 spd would it?

 

Look at all these Vancouverites.

As mentioned above, rich conditions usually attribute high HC levels. Do you have any modifications to the car? As soon as MAP FI system has a change of almost anything it goes extremely rich. My last IROC with cam/heads was getting 6-8 mpg in the city; or 200km to the tank.

 

Man, I passed the driving test with no cats at all. I just put in 94 Mohawk and about 6L of Methyl-hydrate. Ran great!! I got HC's to 1/2 the limit. You'd never know I didn't have cats except I failed the idle by 4X.

I have a 90 Firebird 305 TPI so it should be pretty much the same.

 

No, its black with the gold pinstripes and the gold spoked wheels. T-tops, 700R4, Hooker cat-back, and Koni Yellows all the way around. Stock heads and cam, though I havent had the time to rip it apart and check, custom airfoil, Amsoil air filter.
The Hooker system sounds great but a little to quite with the 305. The Konis are nice, but if I set them to the stiffest setting it is too stiff for my car, and it jumps around all over the place when I hit a bump.
Right now I am looking into replacing the sad little 2.73's I have I have in the rear with 3.73's and possibly add disc brakes back there as well. The easiest way to do that would be to pull the whole rear end and put one from a S10 or Blazer in it right?
I think the thermostat is just the stock replacement, as I went into Deckers and asked for one for my car. It still has the stock chip in it though I think il be upgrading it with the GM prom sometime soon i hope.

 

Before Aircare had you recently disconnected the battery?
It does take sometime for the ECM to learn again and will run rich.
Did you ever pull any codes?

 

No I dont think that the battery has been disconnected since I installed my alarm over 4 months ago. I would hope that it doesnt take that long to learn...
I have not had a chance to pull any codes at all. But what I am wondering is if I am going to get anything because the light is never on?

 

Well, I think you answered your own question. Advanced timing will increase hydrocarobns. Retard your timing and you should make it.

Auggie

 

Pretty much stock everything with no codes you should pass if your cat is working. Are you single or dual cat ? You may need new cat(s) if you idled for that long and still failed.

Which station did you go to ? Some are easier than others.

 

also, it depends where you live, but you could always slip the aircare guys $20. The ones here make minimum wage, they have to sit around there sucking down exhaust fumes all day for the lowest pay legally allowed. so they're pretty easy to bribe here....

 

Make sure to set the timing to the stock figure (6* btdc IIRC), and check for vacuum leaks. High HC indicates that your engine isn't burning fuel well. Having 94 octane will only hurt you, because you don't need it. Unless you advance your timing or somehow higher your compression, it won't burn as well(as complete), so you should switch back to 87 octane. Also, the catalytic converter reduces hydrocarbons. So if what I said fails, it may be bad.

 

Does the engine still have a working A.I.R. pump? Is the diverter valve still working?

And when you said "the light is never on? " does that mean even at start-up?

 

Hmm.... I gues I will set my timing down to 6* and if you are correct about the higher octane fuels not burning as complete, then I will have to step down to 87 again. Though I thought it was always the other way around, and that higher octane fuels burned cleaner.
I went to one in Burnaby near BCIT actually. It it a large facility and I dont think I can slip the guy $20, even if I did my car would still not be running as best as it could be. At this time I am looking into doing more mods, and I would rather upgrade the toasted components than perfectly good ones.
You will have to excuse my ignorance here but what is an A.I.R. pump? Diverter valve? I can feel my way through most of the actual mechanics of my car, but I have a long way to go when it comes to the damn computer and emmisions crap.
The SES light only comes on with ignition, and goes out when the engine is started.
You dont think that my leaking valve seals have much to do with the HC levels?
Anyways thanks for all the help youve given me so far, been a real help. Keep the tips coming! :hail:

 

A.I.R.= Air Injection Reaction. That consists of the air pump (smog pump) the Diverter valve (P.E.D.E. 's valve) The black unit that the hose from the air pump goes to then the hoses that connect to the checkvalves that are hooked to the little tubes coming off the exhaust manifolds, there is also another tube going down to the converter.

Is your charcoal cannister intact? Might want to look into maybe changing the filter on the bottom of it (if it has one, not all do).

 

and if your cat is ...???how old..you might check it out and make sure it is flowing freely....

 

I just took the car into the shop and got my mechanic to take a quick peek at in with his computer. The HC levels were averaging ~50ppm rather than the 155 at the aircare center, but he said that he cannot accuratly recreate the effects of the car being on the rollers. He said that a new cat would be a good idea, and I priced a high performance 3" cat at Mopac for $160CDN. Just waiting till monday for my mechanic to see if he can get a better price for me. Then I need to get the thing welded on... another $75 or so . Oh well at least my car will sound better with the new 3" cat.
It seems as though all my emmision control sensors and crap are all working as they should. So I dont have to deal with them, Yay!
I just found out that my timing was for sure set at 8*, but we hooked a timing light up to it and its at 6* so the computer must have retarded it. Is there any downfalls to having the computer retard the timing other than at startup its a tiny bit rougher?

 

Advanced. The reading they take at idle is with the ESC wire connected, so it would be advanced from the 6* base timing that you set wth the ESC wire disconnected.

 

Don't worry too much about hte filter on the bottom of the EVAP canister. IIRC, after the 1987 year, there was no filter pad, and the canister was (is) considered a throw-away replacement unit.

 

as far as wanting a rear i'd recommend finding a posi for it rather then a locker out of a truck.. i'd look for one out of a 3rd or 4th gen f-body.. 4th gens are slightly longer however and require a different offset wheel.. you can put your stock ones on but they look a tad silly.. but its a great idea if you plan to put 4th gen wheels on

 

Do not run methyl-hydrate in a fuel injected motor, unless you want to ruin your injector seals.

How about trying a product called guarenteed to pass.