I have a 2002 Pontiac Grand Prix.  Over the last few
weeks i have had trouble with the can being jerky while accelerating also i tends to do this more the
warmer the car gets IE: runs good in th am but by lunch time it's acting up. Also i noticed this morning
that the tranny didn't seem to be shifting from 3rd to drive please help any advice will help.  Thank you.

Could you give me a little more info please. Do you have any
engine light or codes stored that you
know of? What is the engine size and mileage of the car. Also, at what speeds are you having the jerky
feeling. Thanks. Will try to give some help after your reply, SF

i have no codes to give sorry.  The jerky feelings happen at all ranges but mostly take off
from 0-50 i have even felt it with the cruise set at 70mph.  The check engine light comes on and then
goes off from time to time i had it hooked up once and they told me in showed no
code so i just thought
it was the gas cap.  The engine is a 3.8 series 2 also the mileage is around 120,000.  Also when the
car jerks i would describe it as wanting to just die the TACH will drop some then pick right back up when
it does this it dose not rev higher though leading me to believe that the tranny is not slipping but like i
said earlier it docent seem to be shifting into drive from third.  At 60 mph the rpm's are at 3000 when
they were normally at 2000-2300 misfire is helps and thank you very much for your time.

OK, thanks. Well, any time the check engine light comes on, there should be a code as current, or in
history, even a loose gas cap. That is really the key to diagnosis. Just by you descriptions, sounds like
you may have 2 or more things going on. A common problem for the jerky condition is a misfire in 1 or
more cylinders. Will need to have the ignition system check- plugs, wires, and also the fuel injectors.
Plug wires and coils are a common area of problems on the 3800. May want to view the
page to see a pic of 'ignition coil inspection' to see what a bad coil usually looks like. Another concern
could be a plugged catalytic converter. They cause a poor acceleration condition (see
question #48
from the
Q & A list for a grand prix with a similar condition). Some engine driveability conditions can
cause odd shifting depending on the engine problem. All goes back to the check engine light codes.
Coil inspecting, pulling trans. Dipstick and check for a nice red color and not a dark burnt color/smell
are some things you can do yourself. After that, getting the codes that are probably still in memory is
the next step.

I need to know the location of the oxygen sensor on a 2002 pontiac grand prix gtp
sedan 3.8L.
That depends on which sensor you are referring
to. There are several oxygen sensors on your car.
how many 02 sensors are on a 2002
Grand Prix with the 3800 engine?
It has 2. One in the rear exhaust manifold, the
other is after the catalytic converter.
2002 Pontiac Grand Prix - V6, 3.1L

When returning from the Grand Canyon to Orange County, California, the
Check-Engine light came on when the car started to struggle when pressing down
on the accelerator, seeming as if not getting the air/fuel it needed, until it reached
the higher gears and started to run smoothly.  Before it reached the final stop, the
Check-Engine light turned off by itself.  When a diagnostic machine was used, it
said that several systems were Okay/Ready, including Misfire, Fuel System, HO2
System, EGR, Comprehension, and Catalyst, while others, including the Evap
System and the O2 Sensor, were Not Ready.  The EGR Valve was changed, but
that didn't help the problem.  Now that the Check-Engine light is off, the diagnostic
tool won't give any further information.
Can you help me?
A) What is/How do I fix/replace the Evap System?
B) What is/How do I fix/replace the O2 Sensor?
C) What other problems/solutions can you think of to assist me in my current
I think you are misunderstanding the scanner
readings. The systems listed as Ready or OK just
means the diagnostic parameters to run the test
for that system were attained, and the test was
run, and in the case of OK- test passed. Systems
that list as Not Ready, means the parameters
were not met, and the test did not run. It does not
mean there is a problem in those systems. You
need to scan the computer for the actual trouble
codes. By what you describe, sounds like maybe
just an engine misfire, possibly a bad spark plug
wire or coil.
Corroded ignition coil and spark plug wire causing engine misfire and check engine light.
Can't locate the transmission modulator on 92 Oldsmobile 98 3800.
While standing in front of the car, it is on the side
of the transmission. The side closest to the
1998 Lumina 3.1 that idles fine but stumbles when accelerator is pressed.  
Replaced coils, plugs, wires, throttle position sensor, and fuel pump.  Problem
remains...any ideas?
About all that is left is a bad fuel injector. You
could also have a rocker arm stud that has pulled
out of the cylinder head, but that usually causes
an engine tapping noise as well.
ok so i took it to the dealer and they told me that the catalytic converter is plugged and the map
sensor is bad which is the reason it is not shifting right.  Then they told me that the recall on the
converter ran out at 120,000 and i have 124,000.  So my next question is will the can run properly
with out the converter or are there sensors built in to it?  Also how do i change the map sensor?  
Car is a 2002 Pontiac Grand Prix.

1- It is against federal emission standards to run a car without converter.
2- With a converter removed you will definitely have a check engine light and codes. The oxygen
sensor behind the converter monitors efficiency. You will get oxygen sensor codes, and possibly
driveability concerns because the computer will be trying to adjust air/fuel ratio after seeing
incorrect readings from post converter oxygen sensor.

I will attach a pic of MAP sensor location and send shortly
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2002 Pontiac Grand Prix Catalytic Converter Codes- No Engine Power