1986 Chevy 305 - failing emissions bad

LukeZ

G-Body Guru
Thread starter
Apr 24, 2015
525
63
Delaware
Okay. Five years straight, you passed the test. Last year you added the catch can. You did not say if you tested last year before or after you installed that can but I am thinking that you did not test at all given the limited amount of road time you suggest occurred.

This year you tested and El Flunko! Were it me I would be looking at the last item to be installed that could have an adverse affect on the emissions; in my mind that would be that oil catch can between the PCV and the manifold. The question in my mind is what happens to the oil mist that condenses in that can once it has filled up? Under normal conditions the PCV doesn't send liquids it sends a sort of light to heavy mist back to the manifold to be incorporated back into the air/fuel mixture. It sort of sounds to me like that can got full and then, during the test, dumped its entire contents into the manifold at once. Way too much oil for the engine to consume and expell. Contemporary two-strokes mix at around 40 to 1 or possibly leaner now. What your engine may have received would have been way richer in ratio by twice as much or worse.

At this point, I would be pulling the plugs to see what the tips look like. The tip off will be a plug tip that is absolutely black and oil fouled and stinking of burnt oil from attempted combustion. Instead of pulling #1 first, head to the firewall and pull #7 and #8. Sometimes they tend to foul out first and could show a good indication of what the rest look like.



Nick
I actually emptied the catch can before the test, but it was about halfway full so maybe the oil had slicked up the engine too much already anyways. I have actually had the rear spark plugs foul up before and had to clean them - I will definitely check them for gunk. I will be replacing all of the plugs anyways so this should be a good indicator. Thanks!
 

scoti

G-Body Guru
Supporting Member
Sep 5, 2019
806
93
Texas
If the vehicle has been dormant, I would put some extended miles on the odometer as well (freeway speeds) before re-testing.
Get some non-ethanal fuel if you can as well. While not available everywhere, it works better for vehicles that have dormant periods.
 
Last edited:

MJScarangella

Master Mechanic
Sep 24, 2020
250
63
Pennsville, NJ
"1986 SS El Camino

MODIFICATIONS: Short throw dipstick, Lambo doors, swiss-cheesed the frame, stick-on vents, Black Ice® Little Tree, lightweight muffler bearings, high performance wiper fluid, VTEC swap, spare tire delete, cross drilled brake lines, drilled and slotted pushrods, Xenon blinker fluid, lightweight license plate, hi-flow glove compartment filter, bullet hole stickers, deleted back seat, turned the hood ornament sideways, and a Flux Capacitor."


This is hilarious.

Hey, Delaware.... You in Sussex, Kent or New Castle county? I live across a bridge from New Castle; do most of my shopping in DE.

One amazing thing about Jersey is zero inspection of cars earlier than 1995.

Bad gas is my bet. I got my car last March with half a tank of God knows how old the gas was. I drove that car sputtering to empty. When I re-filled and changed fuel filter on carb it ran nice with CCC, but stank. Apparently my catalitic converter's honeycomb had blown down into the muffler.
 
  • Agree
Reactions: 1 user

LukeZ

G-Body Guru
Thread starter
Apr 24, 2015
525
63
Delaware
If the vehicle has been dormant, I would put some extended miles on the odometer as well (freeway speeds) before re-testing.
Get some non-ethanal fuel if you can as well. While not available everywhere, it works better for vehicles that have dormant periods.
Maybe I'll just drive to the end of the half-tank of old gas that I have in the car, and then hit her with some fresh gas. I'll definitely get her on the highway for some cruising at speed. Thanks for the advice
 

JimmyCamino

Greasemonkey
Dec 15, 2020
101
28
Alexandria, VA
Bummer that Delaware requires emission tests even on antique registrations. Virginia exempts passenger vehicles older than 25 years, too.

Excessive HC generally means too rich. But sucking dirty oil doesn't help either. And the catalytic converter helps some but can't do that much. Hard part about emissions is you don't know how your mods / "repairs" are performing until you take it in for the official test. Unless you have an exhaust gas analyzer or can read signals off the O2 sensors. If the repairs advised here don't get you through the re-test, seek professional help.
 

LukeZ

G-Body Guru
Thread starter
Apr 24, 2015
525
63
Delaware
"1986 SS El Camino

MODIFICATIONS: Short throw dipstick, Lambo doors, swiss-cheesed the frame, stick-on vents, Black Ice® Little Tree, lightweight muffler bearings, high performance wiper fluid, VTEC swap, spare tire delete, cross drilled brake lines, drilled and slotted pushrods, Xenon blinker fluid, lightweight license plate, hi-flow glove compartment filter, bullet hole stickers, deleted back seat, turned the hood ornament sideways, and a Flux Capacitor."


This is hilarious.

Hey, Delaware.... You in Sussex, Kent or New Castle county? I live across a bridge from New Castle; do most of my shopping in DE.

One amazing thing about Jersey is zero inspection of cars earlier than 1995.

Bad gas is my bet. I got my car last March with half a tank of God knows how old the gas was. I drove that car sputtering to empty. When I re-filled and changed fuel filter on carb it ran nice with CCC, but stank. Apparently my catalitic converter's honeycomb had blown down into the muffler.
haha glad I'm not the only one getting a kick out of it!

Also, live in Kent county - but the state is so small, I'm in all 3 counties every week whether its for work or seeing friends or whatever

Damn, you guys might have some mean taxes over there but that no pre-1995 inspection sounds pretty awesome. If this car won't pass, I guess I know where I'm moving to haha
 

LukeZ

G-Body Guru
Thread starter
Apr 24, 2015
525
63
Delaware
Bummer that Delaware requires emission tests even on antique registrations. Virginia exempts passenger vehicles older than 25 years, too.

Excessive HC generally means too rich. But sucking dirty oil doesn't help either. And the catalytic converter helps some but can't do that much. Hard part about emissions is you don't know how your mods / "repairs" are performing until you take it in for the official test. Unless you have an exhaust gas analyzer or can read signals off the O2 sensors. If the repairs advised here don't get you through the re-test, seek professional help.
Yea I guess I can add VA to my list of potential places to move as well if this car won't pass inspection haha

I'm hoping that after emptying the gas tank, getting new gas, and changing oil/filters and spark plugs, she'll run good enough to pass the test. Just needs to work this one last time!
 

Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
2,668
113
Galaxy far far away
What is your A/F mixture solenoid dwell? If your plugs are gunked up so will be your O2 sensor. The PCV is a controlled vacuum leak, the catch can could be leaking additional vacuum and leaning out your fuel mixture. A lean exhaust is much more pungent than a rich exhaust.
 

LukeZ

G-Body Guru
Thread starter
Apr 24, 2015
525
63
Delaware
What is your A/F mixture solenoid dwell? If your plugs are gunked up so will be your O2 sensor. The PCV is a controlled vacuum leak, the catch can could be leaking additional vacuum and leaning out your fuel mixture. A lean exhaust is much more pungent than a rich exhaust.
I think the catch can is sealed up pretty well - the PCV still has good suction. I may just bypass the catch can for the re-inspection anyways.
Thanks for the tips!
 

JD1964

Greasemonkey
Dec 31, 2014
179
63
I had an 86 Pontiac 6000 4cyl that just would not pass the tailpipe test. Everything was functional and set to factory specs. Retarded the ignition timing to 0 and it passed easily. Ran like crap but passed. After the test I returned the timing spec.
 
  • Like
  • Clever
Reactions: 1 users
G-Body Performance Upgrades

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck ConsolesDixie Restoration DepotMike's MontesP-S-TSouthside Machine PerformanceUMI Performance

ContactAdmin@GBodyForum.comfor info on becoming a sponsor