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Passing Smog [message #271125]

Tue, 03 February 2015 18:27

Jarrar

Messages: 41
Registered: July 2014
Location: Santa Cruz, California.

Karma: 0

Member

How are you?

I have a 1977 GMC 23ft transmode.

Went to smog it yesterday/Monday and it did not pass.

I drove it about 30 miles on Sunday and about 6 miles on the freeway on Monday before I went for the smog check. I also left it running till the mechanic got to it. I had put $50 of fresh gas in the tanks on Sunday.

The part that it failed is the Idle test which according to the paper was at 928 RPM. I looked at the RPM gauge in the RV and the idle is at 750 in Park and around 600 in N.

So why is this idle at 928 RPM?

It failed the CO measuring at 5.11 and the maximum is 3.00

Any advice on what I can do please to make it pass ?

Thank you,
AJ

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Re: [GMCnet] Passing Smog [message #271126 is a reply to message #271125]

Tue, 03 February 2015 18:41

Len Novak

Messages: 676
Registered: February 2004
Location: Las Vegas, NV

Karma: -3

Senior Member

928 seems a tad high, where are you located?

Len and Pat Novak
1978 GMC Kingsley
The Beast II with dash lights that work and labels you can see!
Fallbrook, CA new email: B52Rule@Roadrunner.Com
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375

www.bdub.net/novak/

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of AJ
Sent: Tuesday, February 03, 2015 4:28 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Passing Smog

How are you?

I have a 1977 GMC 23ft transmode.

Went to smog it yesterday/Monday and it did not pass.

I drove it about 30 miles on Sunday and about 6 miles on the freeway on
Monday before I went for the smog check. I also left it running till the
mechanic got to it. I had put $50 of fresh gas in the tanks on Sunday.

The part that it failed is the Idle test which according to the paper was at
928 RPM. I looked at the RPM gauge in the RV and the idle is at 750 in Park
and around 600 in N.

So why is this idle at 928 RPM?

It failed the CO measuring at 5.11 and the maximum is 3.00

Any advice on what I can do please to make it pass ?

Thank you,
AJ
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Len and Pat Novak 1978 GMC Kingsley The Beast II with dash lights that work and labels you can see! Las Vegas, NV new email: B52sRule@Gmail.com http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375 www.bdub.net/novak/

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Re: [GMCnet] Passing Smog [message #271127 is a reply to message #271125]

Tue, 03 February 2015 18:46

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

928 rpm MIGHT BE a bit into the centrifugal advance and just a scosche bit
into the transition range off idle. Is that figure mandated by C.A.R.B. In
California? It needs to have a bit more idle air to reduce the CO. There
is always a bit of difference between readings on the on board tach and the
diagnostic center tach. I thought that they were supposed to conform to the
underhood sticker, but ????
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Feb 3, 2015 4:28 PM, "AJ" wrote:

> How are you?
>
> I have a 1977 GMC 23ft transmode.
>
> Went to smog it yesterday/Monday and it did not pass.
>
> I drove it about 30 miles on Sunday and about 6 miles on the freeway on
> Monday before I went for the smog check. I also left it running till the
> mechanic got to it. I had put $50 of fresh gas in the tanks on Sunday.
>
> The part that it failed is the Idle test which according to the paper was
> at 928 RPM. I looked at the RPM gauge in the RV and the idle is at 750 in
> Park and around 600 in N.
>
> So why is this idle at 928 RPM?
>
> It failed the CO measuring at 5.11 and the maximum is 3.00
>
> Any advice on what I can do please to make it pass ?
>
> Thank you,
> AJ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Re: Passing Smog [message #271133 is a reply to message #271125]

Tue, 03 February 2015 19:24

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

Jarrar wrote on Tue, 03 February 2015 17:27

How are you?

I have a 1977 GMC 23ft transmode.

Went to smog it yesterday/Monday and it did not pass.

I drove it about 30 miles on Sunday and about 6 miles on the freeway on Monday before I went for the smog check. I also left it running till the mechanic got to it. I had put $50 of fresh gas in the tanks on Sunday.

The part that it failed is the Idle test which according to the paper was at 928 RPM. I looked at the RPM gauge in the RV and the idle is at 750 in Park and around 600 in N.

So why is this idle at 928 RPM?

It failed the CO measuring at 5.11 and the maximum is 3.00

Any advice on what I can do please to make it pass ?

Thank you,
AJ

It sounds like your tach is off. Also, I don't understand why the RPM would be different in park vs neutral--did you mean drive? A lower rpm will help and I would lean out the idle mixture screws into the zone where the idle rpm is going down as you scrw them down. You can always bsck them out later.

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: Passing Smog [message #271136 is a reply to message #271125]

Tue, 03 February 2015 19:44

bwevers

Messages: 597
Registered: October 2010
Location: San Jose

Karma: 5

Senior Member

I hope you didn't have to pay them.
Sounds like it needs a tune up.
Plugs, timing, idle speed and mixture adjustment.
We used to retard the ignition timing to get the CO down.

Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose

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Re: Passing Smog [message #271162 is a reply to message #271136]

Wed, 04 February 2015 02:51

Jarrar

Messages: 41
Registered: July 2014
Location: Santa Cruz, California.

Karma: 0

Member

Guys thank you for the replies.

I am in Santa Cruz, CA.

There IS a difference in the RPM when it is in Neutral and Park.

Can you guys give me steps I can take/Do in plain english please?

I took out the plugs and adjusted the gap, it was .60 as I recall, made it smaller so it is not overloading the ignition system.

The wires seem to be in decent shape so is the cap and rotor.

How do I adjust the Carb so it is not running rich,...etc.

Plain english please.

Thank you.
AJ.

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Re: [GMCnet] Passing Smog [message #271165 is a reply to message #271162]

Wed, 04 February 2015 04:05

Mr ERFisher

Messages: 7117
Registered: August 2005

Karma: 2

Senior Member

Take it to a shop that will tune it till it will pass
Like Jim'k

On Wednesday, February 4, 2015, AJ wrote:

> Guys thank you for the replies.
>
> I am in Santa Cruz, CA.
>
> There IS a difference in the RPM when it is in Neutral and Park.
>
> Can you guys give me steps I can take/Do in plain english please?
>
> I took out the plugs and adjusted the gap, it was .60 as I recall, made it
> smaller so it is not overloading the ignition system.
>
> The wires seem to be in decent shape so is the cap and rotor.
>
> How do I adjust the Carb so it is not running rich,...etc.
>
> Plain english please.
>
> Thank you.
> AJ.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>

--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: Passing Smog [message #271190 is a reply to message #271125]

Wed, 04 February 2015 11:41

Wayne

Messages: 106
Registered: August 2004

Karma: 0

Senior Member

A few years back, mine failed just like yours.

I adjusted the idle screws and speed as per the service manual (GM called it the lean drop method) It then passed easly. To do it correctly you need a vacuum gauge and tach.

I have posted a photo of the page on our photo site. Here is the URL: http://www.gmcmhphotos.com/photos/lean-drop/p41047-lean-drop.html

good luck,
Wayne

Wayne Lawrence
76 Birchaven
Bellflower CA
w.lawrence@verizon.net

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Re: Passing Smog [message #271204 is a reply to message #271125]

Wed, 04 February 2015 17:08

Jarrar

Messages: 41
Registered: July 2014
Location: Santa Cruz, California.

Karma: 0

Member

Anyone in Santa Cruz or nearby can help me do these adjustments on the Carb and engine so it passes Smog?

I simply don't have the equipment or the space to work on it.

Anywhere near Santa Cruz, California please.

Thank you all so much.
AJ

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Re: [GMCnet] Passing Smog [message #271240 is a reply to message #271126]

Thu, 05 February 2015 16:58

Jarrar

Messages: 41
Registered: July 2014
Location: Santa Cruz, California.

Karma: 0

Member

I am in Santa Cruz, CA.

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Re: Passing Smog [message #271293 is a reply to message #271125]

Fri, 06 February 2015 10:07

mikeceli

Messages: 20
Registered: January 2015
Location: N. Ca.

Karma: 1

Junior Member

http://www.carsdirect.com/car-maintenance/7-common-reasons-for-failing-an-emissions-test

Cali wants the OP's GMC and all older vehicle, CRUSHED.

I recommend you NOT deviate from OE tuning specs(plug gap) , except perhaps retard the ignition timing 2-3 degrees. (cali allows only so much timing retard/advance or it's an automatic failure. I'm not sure how much, 2-4 degrees or so)

This sounds like a job for someone like Applied GMC, in Newark, Ca. The ignition system, carb, catalytic converter should be tested and repaired as indicated.

If you feel you can.........spray a can of carb cleaner, in the carburetor, slowly while keeping the engine running. CAUTION MUST BE DONE PROPERLY TO NOT CATCH FIRE After cool down, Id pull the plugs again, put 3 OZ. of Seafoam (avail at NAPA, O'Reilly's, Walmart) in each cylinder. Let it sit, overnight, then before installing the plugs, crank the engine to expel the Seafoam. Install new or KNOW GOOD set of OE spec spark plugs.
(NOT Bosch Platinums)!

These procedures will make smoke like HecK! Possibly not doable in SC, CA. Your gonna want to change the oil and filter, after the above treatments.

The ignition wires, cap, rotor, coil will need testing, professionally if you don't have the tools and knowledge.

You might end up needing a new CAT (if originally equipped). Cats are tested by measuring the input and output temps, with the engine running. Also, strike w/ rubber mallet, to hear loose, cracked substrate. If you have the OE "Pellet" CAT, it's likely failed. That is another "cali NIGHTMARE! Cats must be CA. Certified which raised the prices from approx. $80.00 to $400.00.

THEN, the idle will need to be set to OE range.

GOOD LUCK!

[Updated on: Fri, 06 February 2015 10:09]

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Re: [GMCnet] Passing Smog [message #271294 is a reply to message #271293]

Fri, 06 February 2015 10:36

Emery Stora

Messages: 959
Registered: January 2011

Karma: 4

Senior Member

What CATALYTIC CONVERTER are you talking about?

Are you really not aware that the GMC motorhome was never equipped with a catalytic converter?

Emery Stora

> On Feb 6, 2015, at 9:07 AM, Mike Celi wrote:
>
> http://www.carsdirect.com/car-maintenance/7-common-reasons-for-failing-an-emissions-test
>
> Cali wants the OP's GMC and all older vehicle, CRUSHED.
>
> I recommend you NOT deviate from OE tuning specs(plug gap) , except perhaps retard the ignition timing 2-3 degrees. (cali allows only so much timing
> retard/advance or it's an automatic failure. I'm not sure how much, 2-4 degrees or so)
>
> This sounds like a job for someone like Applied GMC, in Newark, Ca. The ignition system, carb, catalytic converter should be tested and repaired as
> indicated.
>
>
> If you feel you can.........spray a can of carb cleaner, in the carburetor, slowly while keeping the engine running. After cool down, Id pull the
> plugs again, put 3 OZ. of Seafoam (avail at NAPA, O'Reilly's, Walmart) in each cylinder. Let it sit, overnight, then before installing the plugs,
> crank the engine to expel the Seafoam. Install new or KNOW GOOD set of OE spec spark plugs.
> (NOT Bosch Platinums)!
>
> These procedures will make smoke like HecK! Possibly not doable in SC, CA. Your gonna want to change the oil and filter, after the above treatments.
>
>
> The ignition wires, cap, rotor, coil will need testing, professionally if you don't have the tools and knowledge.
>
> You might end up needing a new CAT (if originally equipped). Cats are tested by measuring the input and output temps, with the engine running.
> Also, strike w/ rubber mallet, to hear loose, cracked substrate. If you have the OE "Pellet" CAT, it's likely failed. That is another "cali
> NIGHTMARE! Cats must be CA. Certified which raised the prices from approx. $80.00 to $400.00.
>
> THEN, the idle will need to be set to OE range.
>
> GOOD LUCK!
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Re: Passing Smog [message #271318 is a reply to message #271125]

Fri, 06 February 2015 17:39

mikeceli

Messages: 20
Registered: January 2015
Location: N. Ca.

Karma: 1

Junior Member

You might end up needing a new CAT (if originally equipped).

Did you not read my post? I said if originally equipped. And no, I was not aware if the GMC ever had cats. I am considering purchasing one, not an owner. Twenty years automotive experience, almost no Motorhome experience.

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Re: [GMCnet] Passing Smog [message #271319 is a reply to message #271294]

Fri, 06 February 2015 17:38

Sammy Williams

Messages: 522
Registered: August 2010

Karma: -2

Senior Member

UNCategorized never had cats. Only if the owners had feline companions
would it have cat s lol Sammy
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Re: [GMCnet] Passing Smog [message #271336 is a reply to message #271318]

Sat, 07 February 2015 02:07

Olly Schmidt

Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...

Karma: 8

Senior Member

Hello Mike,
> [..]
>
> Did you not read my post?

That was uncalled for. Comes over very nasty from my point of view, even
if you probably didn't intend any nastiness. This is the GMC Motorhome
place. If you copy/paste stuff from another source, it might make sense
to verify that the statements in there are applicable.

> [..]I am considering purchasing one, not an owner. Twenty years automotive experience, almost no Motorhome experience.

It is great to have someone with long experience around. Welcome.

And when you do have a GMC Motorhome, go and enjoy it.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, VA

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Best regards

Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany

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