Help!! Won't Pass Smog!!!

[BlackBeautyGN]

I have a 1987 Grand National. It has 19,200 original miles on it. It was stored in my garage for 11 years and was taken out in November. Smogged it for the first time and it failed test at idle but passed crusing test. Technision recommended replacing catalitic converter. Second test, failed and produced even more emissions. Then they recommended a major tune up. Replacing plugs, air filter and wires. Third test, failed the idle test barely and passed cruising. What do you think it is? Any help would be appriciated. Thanks!

 

[The Radius Kid]

Maybe time for a new fuel pump.
Could be some vacuum leaks due to rotten ruber lines.
Don't forget to check the line to the vacuum ball under the driver's,front fender.

 

[turboCR]

THese cars are marginal in Ca at best. I barely pass each time. Were you high on Nox or HC?

That will assist me.

 

[TurboDave]

A car that has sat that long is certainly going to need new just about everything! Plugs, wires, EGR checked out! New cat, new fuel pump, and good check out by somebody that knows their way around these cars! I just left CA last year, it aint going to be a cake walk, but can be done.

 

[BlackBeautyGN]

I was high on Stage 2: Idle RPM HC. Max allowable is 120. I got 172.

 

[GNX]

Injectors that sit for that long could be varnished. Try either backflushing or replacing. Pour a couple of bottles of Chevron Techrolene into the tank and drive it for a couple of hundred miles after the cleaning.

Don't go to a dealer. Get one of the guys on this board that knows how to tune, check it out. I've had a set of KB silicone plug wires for TEN YEARS and they still ohm out identically, to the same ohms, as when they were new. Whenever I have to get new wires I'll go with the same.

Make sure that you have the stock chip, or one with a stock profile, in it.

 

[jastrckl]

what was your coolant temperature up to on the idle test? hope it was up near 200. running the car around before you go have it tested is a good idea, in order to heat up the catalytic converter. cold, they can't convert hc's into water.

 

[GN-231]

Your EGR is probably stuck if it sat there for 13 years. Pull of the round plastic cover, reach your hand under the shiny metal saucer and push the diaphram of the EGR up a few times to free it up. I would recommend changing plugs, wires, check your TPS settings, check the AIC settings, change the oil, test the vaccumm on the car, maybe put in a new fuel filter & adding the fuel cleaner. These tune up procedures I have listed above are very easy and you should be able to do them yourself without any problems on a saturday afternoon. I would probably drive the car around for a week after all the tune up stuff and also give it a couple WOT stomps to blow the carbon build up off the valves. Go to www.gnttype.org if you need to look up more on the procedures.

If you don't have a scanmaster.....get one.

 

[turboCR]

Check your radiator cap for the Higher pressure cap. A lot of owners, including me, run the Low pressure cap to keep temperature down, then I re-install the HP cap for the emissions test.

I would also suugest getting the engine thoroughly warmed up before the test. I mean thoroughly. Run it on the freeway for several miles.

EGR check is a must too. Put the original gap back on the plugs for the test only. Think LEAN.

UNder the best of circumstances you won't pass HC by much. Last time I made it by 3 ppm.

 

[TurboDave]

Originally posted by turboCR
(snip)
Think LEAN.
(snip)

Why???

All that does is raise the HC levels making it even more difficult to pass!!!

THINK STOICEOMETRIC!! NOT Lean, NOT Rich.

 

[turboCR]

That's what it took for me to pass. Sorry only my $.02 worth.

 

[jastrckl]

No, leaner is LESS hydrocarbons. More oxides of nitrogen, and carbon monoxide instead of dioxide. If he's failing from high HC's, he needs to try to run hotter and leaner. It seemed like he had room for increased NOx and CO emissions, so he should be able to get away with it.

 

[turboCR]

That was always my experience. May each car really has its own gremlins inside that run things. I'l still looking for mine. May be it will take another 203,000 miles.

More opinions? May be someone works for the state of CA and owns a GN. The other sugesstion that never fails is to put the probe in a new Honda's tailpipe, and run the test that way. I think it will pass. OF course I am not condoing this.

 

[gofstbuick]

Originally posted by turboCR
THese cars are marginal in Ca at best. I barely pass each time. Were you high on Nox or HC?

That will assist me.

This guy (BlackBeautyGN)lives in a Basic area of CA, a two speed idle area (tested a idle and 2500 rpm). Only test HC and CO. If his car is basically stock, it should blow zeros across the range.
TurboCR, I may be able to assist you, email me.

 

[GNX]

Originally posted by TurboDave


All that does is raise the HC levels making it even more difficult to pass!!!

THINK STOICEOMETRIC!! NOT Lean, NOT Rich.

I passed way below all parameters last time out. Southern California Test Only Station!

My fuel pressure was 45 PSI with the line off. Blue Tops!

I used a stock profile chip and went in warm 180-185. It was made for the Blue Tops and 45 psi.

If I turned the FP down to 40-38-35 psi with the line off, I wouldn't have passed because the chip will automatically compensate and it will run RICH after a few minutes. You need a chip programmer to explain the cells and what they'll be doing.

Hate to say it guys but Dave is RIGHT! Unless you know how to burn your own chips, I wouldn't try and get your car to pass with only messing with turning your FP down. If you did, that wasn't the reason the car passed unless the chip was originally made for the lower fp reading. JMO

 

[v8rob]

I also failed emissions test, need help.

my '87 GN also failed the Texas emissions test today. Actually, it failed about 6 times. - I was able to make adjustments to the car and keep trying it.

The car has 21k orig. miles and no cat. I did all the usual things to prepare for an emissions test, changed the oil, fuel filter, spark plugs. The EGR diaphragm seems to be working fine. coolant temp was up around 210-220. After some tweaking, we could get the HC's down to just barely under the limit, but we never could get the NOx's where they needed to be.

I was using an "emissions" chip for the stock injectors. We played with the fuel pressure and tried it at various settings from 38-44 psi. Funny thing, increasing it from 38 to 40 actually dropped the HC's.

Any ideas on what I need to do to get it to pass, other than the obvious - put a cat back on it.

Thanks,
Rob

 

[jastrckl]

You're going to need a cat to pass unless your car is in GREAT shape. It's a 16 year old pushrod motor with some design quirks, it's not really a clean emissions design. When you turn down the fuel to blow less HC's, you wind up lean and create some NOx and whatnot. You need a cat so you can run richer and let the extra HC's in the exhaust get converted to water (steam), and avoid producing the NOx altogether.

 

[v8rob]

I understand what you're saying. That's one good thing that came out of hours of tuning, tweaking and multiple emission dyno runs - I now have a much better understanding of what pollutants are caused by. And how tuning changes affect the combustion process.

As for the condition of the engine, that's what's frustrating. The car only has 21k orig. miles and has been pretty much pampered the whole time. I know several guys in this area that pass the sniffer test with much higher mileage engines, more mods and no cat.

One thing I forgot to mention, I was running 93 octane during the tests. Should I have dropped to 87 octane? I know the lower octane burns faster, so I'm thinking maybe I could run lower octane to keep the HC's down and increase the fuel pressure a little to cool the combustion chambers more and hopefully reduce the NOx's.

any ideas?

 

[gofstbuick]

v8rob
What kind of modifications have been done to your vehicle? Because my car passed CA emissions test with flying colors. I looked into TX emissions program and it looks like it now mirrors CA program. Here are some things to thinkabout regarding NOx:

The factory setting is pretty lean, and sometimes trying to obtain a little richer mixture will help.

CA requires the vehicle to be tested in drive, not overdrive and at 15 mph, Nox reduction is totally reliant on the catalytic converter (no EGR in second gear), so a good three way cat is imperative. By the time you hit 3rd gear, NOx reduction will be a combiation of the CAT and the EGR system.

Make sure your O2 sensor is working good, because it helps to maintain stoichiometry, probably within a range of 14.5:1 (slightly rich) to 14.9:1 (slightly lean). The slightly rich side helps control NOx (in the CAT) by extinguishing the mixture and reducing temps that would create NOx and the slightly lean mixture helps the CAT control HC and CO by using the extra oxygen (stored in the CAT substrate material) to complete combustion.

 

[v8rob]

gofstbuick,
engine mods are: Walbro 307 hotwired, adj. FP reg., Pete Tomka cold-air package, Duttweiler neck on stock IC, coolant by-pass in TB blocked off, Hemco upper plenum, Kirban valve springs, Fel-Pro valve seals and 160 t-stat. (actually, I now have some doubts about the t-stat, it was supposed to be in there when I bought the car, but I have ordered a new one just to be sure.)

For the emission testing I changed the oil, installed a new GM O2 sens., new GM fuel filter, new AC Delco R43TS gapped at .035 in. and new plug wires (the wires I had on it were perfectly good until I pulled one of the terminals off while changing the plugs )

I know it will pass with a cat., but I will have some difficulties reinstalling it (long story).

I'm frustrated because I know the engine is in good shape, it *should* pass. I know of several Buicks around here that pass without a cat.