Hi. I have a 1997 Pontiac Grand Prix that i bought
last week. It ran great no CEL ON. Hot a coolant
flush, oil change and my husband did a tune up
cause it was showing signs of needing one. New
plugs and wires, He could not get one plug out so
he left it. Went to get
emissions test and computer
wasn't ready. Still no check engine light on. Drove
for 5 or 6 days no problems. Went back 2 days
ago to get emissions and passed yesterday
CEL flashing.

Came on, spit and sputter and cut off no power no
lights no nothing. Car sat for a few minutes with
battery cable off put back on, had power then tried
to start no luck. Let it sit a little longer started fine
no CEL. Drove multiple places no problems. Went
somewhere late last night engine light started
flashing. The car spit, sputter and then cut off. Did
not start back up. Had to get pushed to the house.
We know a flashing CEL is a misfire so we
assumed it was the spark plugs not changed this

Sprayed nut buster on plug and got it out.
Replaced with brand new. Tried to start and no
start. Engine light still on. We hear the fuel pump
so we know that's fine. Help. I don't know what to
do next. This is our only vehicle. We had the same
thing on ours after we got a transmission rebuild
and there are 3 sensors on the outside of the
trans. You can see one when you move the air
filter housing. That's what we were told was the
reason for that.
Ok, there could be a few different things causing your issue. First of
all, just because you can hear the fuel pump does not mean it's
putting out enough pressure to start the car. I would highly
recommend doing a fuel pressure check to see if it's within spec.
You should have at least 45psi with the key on for your particular
vehicle. If it's any lower than 40 you need a new fuel pump. Check
the fuel filter as well, it can be heavily clogged and cause a low
volume situation.

You may also want to check the
fuel pressure regulator for any
signs of leaks. If the rubber diaphragm inside it is ruptured, it will
leak gas through the vacuum line into the intake. This would cause
a rich condition (too much fuel) which can cause sputtering and
hard starts. Another thing to do would be to re-check all your
previous work. Maybe a spark plug got cracked upon installation,
maybe a wire was left loose or improperly installed, maybe a spark
plug had the gap closed by accident.

All possibilities.I would also highly recommend getting the car
codes scanned to see what trouble codes are making the check
engine light come on and/or flash. That will definitely help lead you
in the right direction for diagnosis. From what you describe it surely
sounds like something with the engine, whether it be electrical, fuel
related, ignition related, or what have you.
1997 Grand Prix CEL Light- Emissions Computer Not Ready

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