Hello all!

This is my first post, Im looking at getting an 85 IROC 5.0 TPI.

I had the current owner perform an emission test before we made any type of deal and the car not only failed the test, it bombed it big time!
I have yet to see the car in person, but while talking with him he told me that the air pump has no belt on it but spins freely, so at some point the pump must have failed, or they just pulled the belt, either way to cat is now garbage. The car failed for NOX abviously, and that doesnt bother me much, a new pump and cat should clear that up. But the car tested at 2600 PPM HC, the max to pass is 175ish. That is an insanely high number. The current owner told me he has adjusted the timing, and though it was OK.
Has anyone had any experience with a car reading this high? Could excessive oil consumption be to blame? He told me it smokes a bit when first started, the reason now is pretty clear. It obviously has a rich condition, or misfiring, but he says it appears the car runs fine. Hes had it for a year but only put 1000 miles on it. He lives an a county with no emission testing required, but Im not so lucky. The car is pretty clean, so Im thnking of picking it up, but the really high HC reading is scaring me off!

Thanks for any help!

 

might pay attention to the hairs sticking up on your neck.

 

Welcome aboard thirdgen.org.

I agree red flags are in order, but some of your assumptions are incorrect. In order:

"...he told me that the air pump has no belt on it but spins freely, so at some point the pump must have failed, or they just pulled the belt, either way to cat is now garbage.".
Myth. I ran my car for 2 years between emissions test with the A.I.R. pump inoperative. When it came time for the next test, I got the system operating, and along with a full tune-up passed the test with flying colors (the technician even congratulated me, because he knew the car had a lot more umph than stock).
"The car failed for NOX abviously, and that doesnt bother me much, a new pump and cat should clear that up."
Wrong. High NOX can be affected by a poorly operating cat, but the A.I.R. system doesn't affect it to any significant degree. It's primarily due to inoperative EGR valve and/or excessively advanced timing.
"But the car tested at 2600 PPM HC, the max to pass is 175ish. That is an insanely high number. The current owner told me he has adjusted the timing, and though it was OK."
High HC is caused by unburned or partially burned fuel. Look for ignition problems (spark plugs, wires, cap, rotor, coil) or low compression due to leaking exhaust valves.
"Could excessive oil consumption be to blame? He told me it smokes a bit when first started, the reason now is pretty clear. It obviously has a rich condition, or misfiring, but he says it appears the car runs fine."
Oil consumption could contribute to high CO, but you didn't mention that reading. Rich will also show up in high CO. The smoke at start-up is the classic Chevy valve stem seal problem, but I doubt that's the problem with the emissions readings (fixing the seals is relatively simple and inexpensive to do yourself - paying a shop to do it will be expensive). Rich (high CO) will tend to suppress NOx, so high NOx is a pretty good indication it isn't running rich. But, smoke at start-up is cause for emissions failure in most states with emissions testing.

In most states, passing emissions is the responsibility of the seller. You didn't indicate where you live, but make it clear to the seller that it's no deal until he gets it to pass AND run properly.

 

OK, well I wont get into an argument over what works and how.

I talked with the owner of the car today, and he said the timing was off. He pulled the spark plugs and sais they looked "OK". He is replacing the air pump and converter and will have it re-tested. I had told him from the very start that the car had to pass or no deal. I'm in Georgia and they dont seem to care about the smoke at start up. I moved here from Colorado, and just the fact that the belt was not on the air pump would have been an automatic failure. They test everythng out there, even my 66 Nova, and 66 VW had to be tested!

What about a defective PCV valve? O2 sensors?

 

Have him put a brand new cat on. That'll cure most of your problem. I bought my GTA with a 2 month old cat & o smog pump at all....I pass emissions tests CLEAN!

Granted, no smog pump means the car SHOULD fail visually, but they typically care more about #s than visual stuff.

 

Well, I am now the somewhat proud owner of a 1985 IROC-Z.

The timing was set correctly, cat, air pump, plugs, and both O2 sensors were replaced and the car passed with flying colors!

The car is in pretty good shape, but it has a few things I will need to deal with.
I need to get all the belts situated, I just drove it with the lights on and the belt, or a belt was noisy. Its missing the Tuned Port Injection badge on the bumper, and a Z28 emblem on the left rocker. The window tint on the doors removed. A good wash and buffing. Other than that its going to be my daily beater!

 

Congrats on the pass and the buy!

The shotgun approach usually covers the target.

(But there's only one O2 sensor on 3rd gens. . . )

 

....That's good news. celebration time...