failed smog - The 1947 - Present Chevrolet & GMC Truck Message Board Network

osaltyone · 10-16-2009, 11:29 PM

Well...I took it in today and HCO was 128 and max allowed was 98 @ 25, was right on the nose for passing at 15. He also wrote Tampered on my slip because my o2 sensor was unplugged and he could not find the wire running to it and aparently my timing was 14 BTDC when he checked it. Should I take it to a smog repair place? The cat was replaced 2 yrs ago because it failed.
Anyone know where the o2 sensor plugs in on an 84 with a 305.

The truck was my dads project and after he passed, I took it on, but know very little about the emissions/engine. I have tore the whole suspension out and bagged it, so I can work on them.

Malo83 · 10-17-2009, 04:13 AM

On my 83 the plug is behind the engine just underneath the distributor, it's a bear to get too when I change out my o2 sensor.
Does your truck have the computer? if so you have to disconnect the 4pin plug coming off the distributor to set the timing at 8*

osaltyone · 10-17-2009, 06:56 PM

I took a mirror and can't see the plug. Maybe I have to look a bit more. I don't think I have a computer on my 84. I thought they started in 87 and 88. If there is a ecu it is not clearly visible.

Zane M · 10-17-2009, 07:52 PM

If you have an O2, you have a computer. I don't know when they started, but there were computer controlled carbs/ignitions before the switch to FI in 87.

grinch4om · 10-18-2009, 05:20 AM

my 84 had a computer that only controlled timing

osaltyone · 10-19-2009, 09:02 PM

Quote:

Originally Posted by grinch4om

my 84 had a computer that only controlled timing

Where was that computer located? I took it to a shop today and they said it did not belong and I needed to take it to the state referee to confirm and certify.

osaltyone · 10-23-2009, 11:13 PM

Turned out to be the damn vacuum lines. I took it to the shop for diagnosis and they said the vacuum lines were all ran incorrectly. They tore them all out and ran new ones, went from 151 on the HC to 88.
Something I should have noticed, but did not have time.

http://67-72chevytrucks.com/vboard/s...d.php?t=367593

10-16-2009, 11:29 PM	#1
osaltyone Registered User Join Date: Jun 2009 Location: Corona, ca Posts: 406	failed smog Well...I took it in today and HCO was 128 and max allowed was 98 @ 25, was right on the nose for passing at 15. He also wrote Tampered on my slip because my o2 sensor was unplugged and he could not find the wire running to it and aparently my timing was 14 BTDC when he checked it. Should I take it to a smog repair place? The cat was replaced 2 yrs ago because it failed. Anyone know where the o2 sensor plugs in on an 84 with a 305. The truck was my dads project and after he passed, I took it on, but know very little about the emissions/engine. I have tore the whole suspension out and bagged it, so I can work on them.

10-17-2009, 04:13 AM	#2
Malo83 Cruzzzn' Vet Join Date: Jan 2005 Location: Porterville,Ca. Posts: 1,918	Re: failed smog On my 83 the plug is behind the engine just underneath the distributor, it's a bear to get too when I change out my o2 sensor. Does your truck have the computer? if so you have to disconnect the 4pin plug coming off the distributor to set the timing at 8*

10-17-2009, 06:56 PM	#3
osaltyone Registered User Join Date: Jun 2009 Location: Corona, ca Posts: 406	Re: failed smog I took a mirror and can't see the plug. Maybe I have to look a bit more. I don't think I have a computer on my 84. I thought they started in 87 and 88. If there is a ecu it is not clearly visible.

10-17-2009, 07:52 PM	#4
Zane M Registered User Join Date: Dec 2006 Location: SLC, UT Posts: 706	Re: failed smog If you have an O2, you have a computer. I don't know when they started, but there were computer controlled carbs/ignitions before the switch to FI in 87.

10-18-2009, 05:20 AM	#5
grinch4om dang its hot Join Date: Nov 2006 Location: frankfort kentucky Posts: 1,349	Re: failed smog my 84 had a computer that only controlled timing

10-23-2009, 11:13 PM	#7
osaltyone Registered User Join Date: Jun 2009 Location: Corona, ca Posts: 406	Re: failed smog Turned out to be the damn vacuum lines. I took it to the shop for diagnosis and they said the vacuum lines were all ran incorrectly. They tore them all out and ran new ones, went from 151 on the HC to 88. Something I should have noticed, but did not have time. http://67-72chevytrucks.com/vboard/s...d.php?t=367593 Last edited by osaltyone; 05-30-2010 at 01:18 AM.



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