I just had 2 new converters put on my car and it still won't pass. My reading went from 8 to 3 but i need 1.6 to pass. Now what?

 

Check for vac. leaks.

Is the air injection working?? (does it have, or supposed to have it??)

What are we working on??


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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R
and 2 POS commuters...

R.I.P. #3
"He can see air"

 

Hydrocarbons are produced by running too rich, if I remember correctly. So lean that puppy out! Or else create a vacuum leak before you go test, that should do it

Incidentally, I put my '62 Bonneville on a tailpipe sniffer just for sh*ts and giggles. At idle, the air/fuel ratio was about 12 to 1, and the hydrocarbons reading was TEN THOUSAND parts per million. I believe the standard for new cars is 200 parts or less. (Emissions controls DO make a difference!)

 

I think he's running lean; if he was running rich, he'd have high CO -and- high HC.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

He DOES have high HC, so either he's running rich or else his AIR system isn't working.

 

Running lean is NOx, I had that cause of some bad power and burn off relays, ya he's running rich, but not sure on the solution.

------------------
1989 GTA 350 TPI
Stock:
- T-tops
- Dual cats
- 9-Bolt 7.75" Rearend
- 3.27 gears
Mods:
- Dynomax Super Turbo Muffler

1992 RS 305 TBI - Sold

 

try backing the timing down a bit.

High HC only could also indicate a severe lean condition where there is not enough fuel to propagate the flamefront leaving unburned fuel in the exhaust.
I had this condition on a previous emissions test(idle). I tried to lean her out and it got worse. So I richened her up and all was good.

Good Luck passing the sniffer.

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LOBC-- SS-84

92 RS Heritage package with a 305 3" high-flow cat and pipe with a Dynomax 3" in dual 2 1/2" out.

84 El camino- 383 CID, Performer RPM, GMPP vortec heads, Holley 750 D.P.(0-4779c), Crane Energizer 274,Dual 3" Flowmaster 40 Series Exhaust, Turbo 350 (375b), TCI 2500 stall, Richmond 3.42 gears, PST Poly graphite Suspension bushings, PST steering linkage, PST springs, Monte SS sway bays, Wheels from a Third gen(does that count?)

 

After the cats, the mechanic tried changing the computer because he said I had an aftermarket one in but it made no difference. The only thing I notice wrong with the car is it has a rough idle which could be caused by a vaccum leak. I haven't checked the AIR system myself but I hope he checked it out to be working. My timing is set at 8dec BTDC which is 2dec advanced. I need to ask him about the air/fuel ratio to see if i am running rich or lean. I will ask him about the things you guys suggested but if the problem is still there i guess i need to cheat. Does the dry gas work and will it cause any harm? Also, would unpluging a injector help any without any harm being done? Thanks for the help so far.

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1989 Formula 350

[This message has been edited by PLANT PROTECTION (edited August 10, 2001).]

 

PP,

You can unplug as many injectors as you want without causing any real harm other than poor idle and rough operation. I've done it many times and for extended periods as a diagnostic practice.

As for the high hydrocarbon counts, UB2 rich, methinks. Unless you have changed the oxygen sensor within the last 25-30,000 miles, you might consider a replacement.

And you'll have a helluva time passing without a working AIR pump and diverter and check valves.

------------------
Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

you might want to give a try at gapping your spark plugs another .005. are there any mods done to the vehicle???

 

I have bosch platnium plugs so i don't think i can re-gap them. My mods are dynomax catback, k&n, accel #21 injectors, and an AFPR set at 48PSI.

------------------
1989 Formula 350

 

Whats the CO reading.??....a low/normal CO reading with a high HC will usually be a vac. leak/lean condition. (bad O2, vac hose, etc.)

High CO with high HC will usually mean a misfire or a poor running cylinder....

I just smogged a little Dodge pick up the other day and it had 2350++ HC and very little CO......All it took to get it cured was a carb adjust...it lost 2300 HC buy just richening it up!!

Food for thought.



------------------
ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R
and 2 POS commuters...

R.I.P. #3
"He can see air"

 

My CO reading is very low.......I think it is a 1.60 with a limit of 20. How much vaccum should be in the system and how do I check it? Also, is 48PSI enough pressure to compensate for my smaller injectors?

 

I would try to cure the rough idle before I went any further....you cure the rough idle and I bet you'll cure your high HC problem...


------------------
ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R
and 2 POS commuters...

R.I.P. #3
"He can see air"