Pontiac Grand Am Runs Bad At Low Speeds
1997 Pontiac Grand am se  2.4L engine light on,
multiple misfire.
We changed
spark plugs, plug wires, map sensor,
o2 sensor, coil housing,
coils, control module,cam
sensor, checked fuel injectors, checked
compression 150%.  New computer.  Had fuel
injectors cleaned out.

Question: Car runs perfect if your driving on
interstate.  Driving through town car won't stay
running, stalls constantly and shakes like crazy.  
Had it to two different mechanics and neither one
of them could figure it out.  Tried everything.  Car
barely runs or starts now.  It started running bad a
few weeks earlier and the problem gradually just
got worse.  Can't drive it at all now.  Did find a
broken line to the gas tank, no fuel in line more like
a vacuum line, fixed that and car ran worse after I
fixed it.
The line you are talking about sounds like the
EVAP emissions
vapor line. That would have nothing to do with the way it is
running. Must just be a coincidence.

You said that the injectors were checked? Were they checked for
proper fuel flow? There is a test to see it the injectors are
restricted by using a pressure gauge and comparing the flow rate
of each one.

You need to get the gas checked. You may have gotten a bad
tank. Have a fuel sample taken and then let it sit a few minutes to
look for any separation or settling. If there is any, then it is
contaminated. Usually it is from water.

If the gas is fine and still wont run at slow speeds, it sounds like
the timing has jumped. Especially is the misfire code is showing
up on all four cylinders. This will not always show up on a
compression test. Best way to check that on this engine is to
remove moist of the top timing cover bolts, turn the engine to line
up the cam gear marks and see if the crank mark is lined up.

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Live Chat:

Question: Joe, I have a question regarding idle on cold start. I
posted a video on youtube and if I give you the address can you
listen to it and give me your opinion?

Answer: Sure.


Year make and model please.

Pontiac Grand AM 2005 3.4l.

Ok. Give me a minute to check it out...

thanks man.

The dealer said its because overnight it loses pressure and it takes
a while to rebuilt that pressure...

What pressure are they talking about?

lol no idea man. he was talking about a spring part... I have a hard
time hearing his because his english is not too good.

Does the engine make noise also under the hood?

at the end of the 30 sec clip you will hear that the strange noise
stops. Then the motor has a clicking sound but only for about 20
second. The idle is not perfect hot or cold too.

Does the exhaust smell?

Only when cold before the exhaust heats up.

Do you think it smells like burning antifreeze, oil, or gas.

Nothing bad. Just burnt gas.

Ok. If you have not done so already and you have the car with you,
check the coolant level and condition. Also pull the dipstick and
see what color the oil is. And one final thing, remove the oil filler
cap to see if it is full of sludge.

I was thinking more like it could be the MAF or PCV or IAT causing
the issue...

No, probably not one of those. Bear with me while I type a pretty
big paragraph of some things I think it could be.

Thanks man.

With watching and hearing the video, and the things you have told
me about the mechanics speaking about a spring, it sounds like
the mechanic is trying to describe that the lifters are taking too long
to pump up. All the lifters have springs inside them. Or he was
trying to tell you one of the valve springs is broken. The engine has
a bad miss fire. Some possible causes and the reason I told you to
check the fluids is possible lower intake manifold leaking coolant
into the oil. Contaminated oill will cause the lifters to bleed down
and engine will run bad until they pump up. Another possibility is
that the fuel pressure regulator is leaking gas internally very badly.
This will also contaminate the oil and wash the cylinders which can
cause engine misfires. Neither of these things will cause a broken
valve spring though. So I think the most probable cause is that the
coolant and oil are contaminated, mixed together. Lower intake
manifold leaking coolant is very common on the 3400 engine.

Ok. I will keep and eye on the coolant and the oil. Thank you for
your help Joe.