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89 pontiac 2.8L surging idle



 
 
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  #1  
Old February 25th 05, 05:53 AM
Steve
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Default 89 pontiac 2.8L surging idle

I have a 1989 pontiac 6000 with the fuel injected 2.8 liter v6 that has
developed a problem with surging/low idle.

The car starts and runs fine when cold (first started in the morning) but as
the engine warms up the engine begins to idle strangely and it surges from
high to low high to low until finally the idle is so low that it stalls. I
can't even stop at a stop light without the engine dying on me.

The engine had a recent tune up so I highly doubt that spark plugs are the
problem as it runs fine on high idle.

What could cause this?


I was thinking that it could be the following:

1. Bad ignition module
2. Bad fuel injectors
3. Clogged throttle body.


Can anyone recommend a course of action for me? The car has 300,000km's on
it and I'm the original owner and I have cared for my car since the day I've
owned it.

Thanks a million



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  #2  
Old February 25th 05, 06:01 AM
Steve
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Default

one more thing... I read that the fuel pressure regulator and fuel rail
could cause this problem.

Can anyone confirm this?
Thanks

"Steve" > wrote in message
news:qbyTd.497870$8l.312150@pd7tw1no...
>I have a 1989 pontiac 6000 with the fuel injected 2.8 liter v6 that has
>developed a problem with surging/low idle.
>
> The car starts and runs fine when cold (first started in the morning) but
> as the engine warms up the engine begins to idle strangely and it surges
> from high to low high to low until finally the idle is so low that it
> stalls. I can't even stop at a stop light without the engine dying on me.
>
> The engine had a recent tune up so I highly doubt that spark plugs are the
> problem as it runs fine on high idle.
>
> What could cause this?
>
>
> I was thinking that it could be the following:
>
> 1. Bad ignition module
> 2. Bad fuel injectors
> 3. Clogged throttle body.
>
>
> Can anyone recommend a course of action for me? The car has 300,000km's
> on it and I'm the original owner and I have cared for my car since the day
> I've owned it.
>
> Thanks a million
>
>
>



  #3  
Old February 25th 05, 07:31 AM
Comboverfish
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Posts: n/a
Default

A surging idle would lead me in the direction of a vacuum leak.
Possibly at the vacuum hose tee or elbow at the rear of the engine
compartment or leaking intake manifold gasket(s).

Toyota MDT in MO

  #4  
Old February 25th 05, 03:48 PM
external usenet poster
 
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Default

It's been a long time since I've owned a GM 2.8L V6, so I don't
remember a lot about them.

Most fuel injected cars have some kind of idle bypass passage in the
throttle body, often with an electrically controlled valve. If that
gets clogged or the valve gets flakey, it can cause the problem you are
experiencing. Sometimes the "valve" mechanism is separate from the
throttle body with hoses going to the intake manifold and the air
plumbing between the MAF sensor and the throttle body.

Also, an oxygen sensor that's going bad can cause surging. So you might
want to check the O2 sensor as well.

--
Racer X

1984 VW Jetta Diesel GT
1992 Mazda Miata (looks OK considering it's been hit by an 18 wheeler)
1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy)
1995 Ford Escort (may it rest in pieces)
1983 VW Rabbit GTI (ITB racer)
1988 Mazda RX-7 (maybe for sale, make offer)
1992 GMC Topkick (portable garage for racecar[s])

  #5  
Old February 26th 05, 12:52 AM
Steve
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Posts: n/a
Default

would a faulty fuel pressure regulator cause that problem too?

> wrote in message
oups.com...
> It's been a long time since I've owned a GM 2.8L V6, so I don't
> remember a lot about them.
>
> Most fuel injected cars have some kind of idle bypass passage in the
> throttle body, often with an electrically controlled valve. If that
> gets clogged or the valve gets flakey, it can cause the problem you are
> experiencing. Sometimes the "valve" mechanism is separate from the
> throttle body with hoses going to the intake manifold and the air
> plumbing between the MAF sensor and the throttle body.
>
> Also, an oxygen sensor that's going bad can cause surging. So you might
> want to check the O2 sensor as well.
>
> --
> Racer X
>
> 1984 VW Jetta Diesel GT
> 1992 Mazda Miata (looks OK considering it's been hit by an 18 wheeler)
> 1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy)
> 1995 Ford Escort (may it rest in pieces)
> 1983 VW Rabbit GTI (ITB racer)
> 1988 Mazda RX-7 (maybe for sale, make offer)
> 1992 GMC Topkick (portable garage for racecar[s])
>



  #6  
Old February 26th 05, 05:56 AM
Comboverfish
external usenet poster
 
Posts: n/a
Default


Steve wrote:
> would a faulty fuel pressure regulator cause that problem too?



All it does is keep pressure at around 35 psi engine running and up to
about 45 psi with no vacuum (vac hose removed, high load conditions).

Check your fuel pressure, or have someone do it if you aren't sure how
to do it safely.

Toyota MDT in MO

  #7  
Old February 26th 05, 02:42 PM
external usenet poster
 
Posts: n/a
Default


Steve wrote:
> would a faulty fuel pressure regulator cause that problem too?
>

The fuel pressure regulator could cause problems like that. Especially
if the vacuum line to it is clogged or damaged. But testing that is a
bit of a pain, and the first two things I mentioned are much easier and
more likely.

Cleaning the throttle body and idle bypass stuff is probably a good
ideaeven if it doesn't solve the problem. I really think it could be a
big part of the problem, though.

And hooking a volt meter up to the O2 sensor and checking it isn't too
difficult (depending on how accessible the O2 sensor connections are).
The voltage should oscillate between two levels. The quicker it
changes, the better it is. If it's very slow to change levels and it
pretty much matches the surging from the engine, that's a good bet that
the O2 sensor is failing and causing the surging. If it reads a
constant voltage, it's dead and needs to be replaced, but it's probably
not the cause of the surging problem.

--
Racer X

1984 VW Jetta Diesel GT
1992 Mazda Miata (looks OK considering it's been hit by an 18 wheeler)
1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy)
1995 Ford Escort (may it rest in pieces)
1983 VW Rabbit GTI (ITB racer)
1988 Mazda RX-7 (maybe for sale, make offer)
1992 GMC Topkick (portable garage for racecar[s])

  #8  
Old February 27th 05, 07:44 AM
Eric F
external usenet poster
 
Posts: n/a
Default

is your check engine light on? If so, you need to read the codes to see
what's going on.
It could be an Oxygen sensor, mass airflow sensor, throttle body plate heavy
coked up..


"Steve" > wrote in message
news:qbyTd.497870$8l.312150@pd7tw1no...
> I have a 1989 pontiac 6000 with the fuel injected 2.8 liter v6 that has
> developed a problem with surging/low idle.
>
> The car starts and runs fine when cold (first started in the morning) but

as
> the engine warms up the engine begins to idle strangely and it surges from
> high to low high to low until finally the idle is so low that it stalls.

I
> can't even stop at a stop light without the engine dying on me.
>
> The engine had a recent tune up so I highly doubt that spark plugs are the
> problem as it runs fine on high idle.
>
> What could cause this?
>
>
> I was thinking that it could be the following:
>
> 1. Bad ignition module
> 2. Bad fuel injectors
> 3. Clogged throttle body.
>
>
> Can anyone recommend a course of action for me? The car has 300,000km's

on
> it and I'm the original owner and I have cared for my car since the day

I've
> owned it.
>
> Thanks a million
>
>
>



 




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