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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / June 2006

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94 Grand Prix starts but stalls

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timinohio@gmail.com - 24 Jun 2006 07:15 GMT
My 94 Grand Prix starts, revs up to about 3000 rpm, and stalls withing
a couple seconds.  I've got fuel and spark, but it still stalls.  Mass
airflow sensor, or maybe O2 sensor?  Can someonepoint me in the right
direction?

Thanks for any help/info.

Tim
jeffcoslacker - 24 Jun 2006 12:39 GMT
Sounds like a catastrophic vacuum leak to me, or it's not sensing intake
air volume correctly, as you said...Make sure the PCV or other large
vacuum lines aren't unplugged, depending what motor you have it could
have a massive intake gasket leak...

But you're on the right track, they throttle way up like that when
there's too much air in the cold start mixture. Could be the IAC also,
not being able to get it into a rich cold engine start idle...can you
keep it running by giving it throttle or no?

EGR stuck open would also do this...

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jeffcoslacker

http://www.automotiveforums.com

timinohio@gmail.com - 24 Jun 2006 15:06 GMT
Forgot to mention it's a 3.4L.  And, working the throttle only just
barely keeps it running and running very roughly at that.  Thanks for
the help so far.

> Sounds like a catastrophic vacuum leak to me, or it's not sensing intake
> air volume correctly, as you said...Make sure the PCV or other large
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>
> http://www.automotiveforums.com
philthy - 29 Jun 2006 00:52 GMT
bad injector  killing the pcm driver
failed oil pressure sensor causing fuel pump kill
factory alrm system shutting down  puter failure to properly maintain vehicle such as plugs,
wires and air filter, fuel filter too
but the first thing to do is pull fault codes

> Forgot to mention it's a 3.4L.  And, working the throttle only just
> barely keeps it running and running very roughly at that.  Thanks for
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> >
> > http://www.automotiveforums.com
timinohio@gmail.com - 29 Jun 2006 09:34 GMT
Philthy - can you point me to the proper scanner to get the fault
codes.  I keep getting told that OBD2 scanners won't work on my 94 GP.
But, surely, SOMETHING can be plugged into the OBD connector and tell
me what's wrong.

Thanks so far for all the info.

Tim

> bad injector  killing the pcm driver
> failed oil pressure sensor causing fuel pump kill
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> > >
> > > http://www.automotiveforums.com
jeffcoslacker - 24 Jun 2006 16:56 GMT
Well you can rule out the O2, because it ignores that signal until the
engine warms up.

What you need to find out here is if it's too lean or too rich that's
causing the condition. When you say it runs up to 3000 then dies, is it
smooth and strong sounding until it checks out?

And does it woof and backfire through the intake when you try to keep
it running with the throttle? Or just chug like it's flooding? Any
sooty exhaust as it dies out?

A defective Coolant Temp Switch will sometimes make something like this
happen on cold starts, but usually causes overfueling and sooty exhaust
and strong fuel odor, along with fuel fouled plugs.

The MAF could concievably cause this, you can have someone thump on it
while you attempt to start it, if it reacts to being bumped, it's
bad...

The 3.4's did have lower intake gasket design problems, sometimes the
gasket would disintegrate and cause leakages. Usually there was coolant
loss involved too when this happens.

This is the SFI SOHC 3.4, right? Not the DOHC? I don't even know if
they put those in Grand Prix, but they were a headache.

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jeffcoslacker

http://www.automotiveforums.com

timinohio@gmail.com - 28 Jun 2006 14:11 GMT
Thanks again, Jeff, for the info and help.

When I get it started, it revs up to 3000 hard and fast and smoothly,
then dies jsut as quickly.

Not sure about the sooty, exhaust; car isn't here, so I can't try it.
I will get back to you.

As for the MAF, I haven't looked at my library's Chilton yet, so I'm
not completely sure where it is located.  Can  you point me to it?

Again, without the car here, I can't be 100% sure, but I believe it IS
the DOHC.  As I recall, the decals on the fender say something like
"3.4L twin DOHC" but I will check that too.

Thanks again.

Tim

> Well you can rule out the O2, because it ignores that signal until the
> engine warms up.
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>
> http://www.automotiveforums.com
gfulton - 28 Jun 2006 15:08 GMT
> Thanks again, Jeff, for the info and help.
>
[quoted text clipped - 44 lines]
>> jeffcoslacker
>> ------------------------------------------------------------------------

I had the DOHC 3.4 V6 in a '92 Olds Cutlass Supreme.  It also started
revving to about 2500 when started.  Checked for vacuum leaks, closed off
the IAC solenoid port, no help.  I finally took a coaster and completely
plugged the intake and the engine still ran at 1500 rpm.  Turned out to the
be intake plenum gasket was cracked in 3 places.  It's not that bad of job
to replace and if that's your problem, check the big vaccum rubber line to
the brake booster while you've got the plenum off.  It's bad about
deteriorating and sucking closed causing a loss of brake boost.  You can't
hardly get to it with the plenum on.  Hope this helps.

Garrett Fulton
timinohio@gmail.com - 29 Jun 2006 09:36 GMT
Garrett-
The booster rubber vacuum line - is it about 3/4" in diameter?  I was
looking around and I saw that this line was swelled, and is spongy to
the touch.  If I have to tear it down to replace the gasket, I'll be
sure to replace the line too.  Thanks for the tip.

Tim

> > Thanks again, Jeff, for the info and help.
> >
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>
> Garrett Fulton
gfulton - 30 Jun 2006 01:50 GMT
> Garrett-
> The booster rubber vacuum line - is it about 3/4" in diameter?  I was
[quoted text clipped - 3 lines]
>
> Tim
That's the guy, Tim.  My wife also complained, along with the high idle
problem, that sometimes she seemed to loose brake boost and had to really
stomp on the pedal.  My line on the engine was dead soft and a real pain to
get to with that plenum on.  Good luck.

Garrett

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