OT (sorta)

It's not a Toyota but it is an automotive issue. My son can't get his
87 Suburban through emissions. Here's my post to a chevy group. Anybody
got any ideas on how to get the darn hydrocarbons down??? Thanks.
jor.
[color=blue]
> jor7 Suburban, 350, Throttle Body Injection
>
> My son is having a rough time getting his Suburban through Arizona
> emissions. The hydrocarbons are really high. He's done all the usual
> (new oil, new PCV valve and so on). He even added a gallon of alcohol
> to the tank. On my old carbureted Ford (sorry) pickups I usually retard
> the ignition a couple of degrees, lean out the idle mixture and add a
> gallon of alcohol. I sail right through emissions. With the TB
> injection though, I'm at a loss how to adjust it so the HC levels are
> acceptable. Thanks.
> jor[/color]

"jor" <jor@jor.com> wrote in message news:2006080206482075249-jor@jorcom...[color=blue]
> It's not a Toyota but it is an automotive issue. My son can't get his
> 87 Suburban through emissions. Here's my post to a chevy group. Anybody
> got any ideas on how to get the darn hydrocarbons down??? Thanks.
> jor.
>[color=green]
> > jor7 Suburban, 350, Throttle Body Injection
> >
> > My son is having a rough time getting his Suburban through Arizona
> > emissions. The hydrocarbons are really high. He's done all the usual
> > (new oil, new PCV valve and so on). He even added a gallon of alcohol
> > to the tank. On my old carbureted Ford (sorry) pickups I usually retard
> > the ignition a couple of degrees, lean out the idle mixture and add a
> > gallon of alcohol. I sail right through emissions. With the TB
> > injection though, I'm at a loss how to adjust it so the HC levels are
> > acceptable. Thanks.
> > jor[/color]
>[/color]

Just a guess here, but maybe a new CAT?

"jor" <jor@jor.com> wrote in message news:2006080206482075249-jor@jorcom...[color=blue]
> It's not a Toyota but it is an automotive issue. My son can't get his 87
> Suburban through emissions. Here's my post to a chevy group. Anybody got
> any ideas on how to get the darn hydrocarbons down??? Thanks.
> jor.
>[color=green]
>> jor7 Suburban, 350, Throttle Body Injection
>>
>> My son is having a rough time getting his Suburban through Arizona
>> emissions. The hydrocarbons are really high. He's done all the usual (new
>> oil, new PCV valve and so on). He even added a gallon of alcohol to the
>> tank. On my old carbureted Ford (sorry) pickups I usually retard the
>> ignition a couple of degrees, lean out the idle mixture and add a gallon
>> of alcohol. I sail right through emissions. With the TB injection though,
>> I'm at a loss how to adjust it so the HC levels are acceptable. Thanks.
>> jor[/color]
>[/color]

High HC is usually the result of incomplete combustion. Make sure the spark
plugs for every cylinder are firing, that they are the correct plugs and in
good condition, and that the high tension ignition wires, rotor, and coil
are in good shape.
--

Ray O
(correct punctuation to reply)

Excessive hydrocarbons is an indicator of incomplete combustion, and since
that can occur from a rich mixture or someting like a lean miss, the HC
number alone cannot be used as an indicator to diagnose anything. Do you
have any of the the other figures from the test like co, nox, or o2?

On 2006-08-02 09:55:43 -0700, "qslim" <Suckers@suckersdotcom> said:
[color=blue]
> Excessive hydrocarbons is an indicator of incomplete combustion, and since
> that can occur from a rich mixture or someting like a lean miss, the HC
> number alone cannot be used as an indicator to diagnose anything. Do you
> have any of the the other figures from the test like co, nox, or o2?[/color]

HC Loaded: 127 (passed)
HC Idle Reading: 477 (standard is 220) = FAIL

CO Loaded: .85 (passed)
CO Idle: .27 (passed)

It passed the Air System, CAT & Gas Cap tests.
Thanks.

"jor" <jor@jor.com> wrote in message news:2006080220152250073-jor@jorcom...[color=blue]
> On 2006-08-02 09:55:43 -0700, "qslim" <Suckers@suckersdotcom> said:
>[color=green]
>> Excessive hydrocarbons is an indicator of incomplete combustion, and
>> since
>> that can occur from a rich mixture or someting like a lean miss, the HC
>> number alone cannot be used as an indicator to diagnose anything. Do you
>> have any of the the other figures from the test like co, nox, or o2?[/color]
>
> HC Loaded: 127 (passed)
> HC Idle Reading: 477 (standard is 220) = FAIL
>
> CO Loaded: .85 (passed)
> CO Idle: .27 (passed)
>
> It passed the Air System, CAT & Gas Cap tests.
> Thanks.
>[/color]

If the HC higher at idle than loaded, I'd suspect a lean miss. Make sure
the throttle body plate moves freely and closes properly, check the ignition
system.
--

Ray O
(correct punctuation to reply)

On 2006-08-02 21:11:35 -0700, "Ray O" <rokigawaATtristarassociatesDOTcom> said:
[color=blue]
> If the HC higher at idle than loaded, I'd suspect a lean miss. Make
> sure the throttle body plate moves freely and closes properly, check
> the ignition system.[/color]

Ray,
We were working on it for awhile last night and discovered that the
EGR had been bypassed. Also, the nuts holding on the EGR will little
more than hand tight. Anyhow, we pulled it and it seemed to function
alright but we went ahead and replaced it anyhow and hooked it back up
(vacuum line). Anyhow, would the bypassed EGR contribute to high HC
readings? Thanks.
jor

The EGR valve only opens under vacuum. I doubt if it is contributing
to the high HC reading at idle.


jor wrote:[color=blue]
> On 2006-08-02 21:11:35 -0700, "Ray O" <rokigawaATtristarassociatesDOTcom> said:
>[color=green]
> > If the HC higher at idle than loaded, I'd suspect a lean miss. Make
> > sure the throttle body plate moves freely and closes properly, check
> > the ignition system.[/color]
>
> Ray,
> We were working on it for awhile last night and discovered that the
> EGR had been bypassed. Also, the nuts holding on the EGR will little
> more than hand tight. Anyhow, we pulled it and it seemed to function
> alright but we went ahead and replaced it anyhow and hooked it back up
> (vacuum line). Anyhow, would the bypassed EGR contribute to high HC
> readings? Thanks.
> jor[/color]

"jor" <jor@jor.com> wrote in message news:200608030656468930-jor@jorcom...[color=blue]
> On 2006-08-02 21:11:35 -0700, "Ray O" <rokigawaATtristarassociatesDOTcom>
> said:
>[color=green]
>> If the HC higher at idle than loaded, I'd suspect a lean miss. Make sure
>> the throttle body plate moves freely and closes properly, check the
>> ignition system.[/color]
>
> Ray,
> We were working on it for awhile last night and discovered that the EGR
> had been bypassed. Also, the nuts holding on the EGR will little more than
> hand tight. Anyhow, we pulled it and it seemed to function
> alright but we went ahead and replaced it anyhow and hooked it back up
> (vacuum line). Anyhow, would the bypassed EGR contribute to high HC
> readings? Thanks.
> jor
>[/color]

The EGR recirculates some exhaust gas into the combustion chamber to lower
combustion temperatures and reduce oxides of nitrogen (NOx). I doubt if the
bypassed EGR valve caused the high HC readings. Some people bypass the EGR
valve in hopes of improving performance and/or drivability.

A dirty fuel injector could theoretically cause the HC to be high at idle.

How does the engine run at idle? With a set of set of park plug wire
pullers, carefully remove one spark plug wire at a time while the engine is
running. The engine should run noticeably rougher when the spark plug wire
is disconnected. If the engine runs the same when a particular wire is
disconnected, then that cylinder was not firing.
--

Ray O
(correct punctuation to reply)

>> <snip>[color=blue]
> The EGR recirculates some exhaust gas into the combustion chamber to
> lower combustion temperatures and reduce oxides of nitrogen (NOx). I
> doubt if the bypassed EGR valve caused the high HC readings. Some
> people bypass the EGR valve in hopes of improving performance and/or
> drivability.
>
> A dirty fuel injector could theoretically cause the HC to be high at idle.
>
> How does the engine run at idle? With a set of set of park plug wire
> pullers, carefully remove one spark plug wire at a time while the
> engine is running. The engine should run noticeably rougher when the
> spark plug wire is disconnected. If the engine runs the same when a
> particular wire is disconnected, then that cylinder was not firing.[/color]

It idles smoothly. I don't think any of the plugs aren't firing but
we'll make sure. Thanks.
jor

"jor" <jor@jor.com> wrote in message news:2006080317324711272-jor@jorcom...[color=blue][color=green][color=darkred]
>>> <snip>[/color]
>> The EGR recirculates some exhaust gas into the combustion chamber to
>> lower combustion temperatures and reduce oxides of nitrogen (NOx). I
>> doubt if the bypassed EGR valve caused the high HC readings. Some people
>> bypass the EGR valve in hopes of improving performance and/or
>> drivability.
>>
>> A dirty fuel injector could theoretically cause the HC to be high at
>> idle.
>>
>> How does the engine run at idle? With a set of set of park plug wire
>> pullers, carefully remove one spark plug wire at a time while the engine
>> is running. The engine should run noticeably rougher when the spark plug
>> wire is disconnected. If the engine runs the same when a particular wire
>> is disconnected, then that cylinder was not firing.[/color]
>
> It idles smoothly. I don't think any of the plugs aren't firing but we'll
> make sure. Thanks.
> jor
>[/color]

Incorrect or bad spark plugs could also keep the fuel from burning
completely so pull the plugs and visually inspect. Sniff the end of the
plugs for a gas smell.
--

Ray O
(correct punctuation to reply)

On Wed, 02 Aug 2006 06:48:20 -0700, jor wrote:
[color=blue]
> It's not a Toyota but it is an automotive issue. My son can't get his
> 87 Suburban through emissions. Here's my post to a chevy group. Anybody
> got any ideas on how to get the darn hydrocarbons down??? Thanks.
> jor.
>[color=green]
>> jor7 Suburban, 350, Throttle Body Injection
>>
>> My son is having a rough time getting his Suburban through Arizona
>> emissions. The hydrocarbons are really high. He's done all the usual
>> (new oil, new PCV valve and so on). He even added a gallon of alcohol
>> to the tank. On my old carbureted Ford (sorry) pickups I usually retard
>> the ignition a couple of degrees, lean out the idle mixture and add a
>> gallon of alcohol. I sail right through emissions. With the TB
>> injection though, I'm at a loss how to adjust it so the HC levels are
>> acceptable. Thanks.
>> jor[/color][/color]

is it in closed loop?