I have a 1999 oldsmobile alero 3.4L V6. Just changed my intake manifold gaskets, fuel injector rings, spark plugs, and spark plug wires. Cleaned out intake manifold, throttle body, and alternator. I also replaced factory air filter with after market air intake. I started the car up and experienced loud whining noise that occurs about every 5 seconds. The RPMs will climb to about 3 when the car isnt warmed up, without even pressing the gas and then it seems like it wants to shut off. This all happens when the car is in park. I can hear the whining noise coming from the throttle posision sensor. The car is drivable but when the car is stopped and brakes are on it shakes pretty bad until I put it in park and apply slight pressure on gas peddle to keep RPMs between 1 and 2 which stops the shaking s little. What will I need to replace and how hard will it be?
SOURCE: 99 OLDS ALERO 2.4 IDLING PROBLEM
intake manifold has a vacum leak or other vacum leak hose etc.
SOURCE: 99 olds alero 2.4
I'm sure you have installed a fuel pressure gauge and monitored the fuel pressure while the problem is occurring?Another diagnostic tool which is easy to do,is while the problem is occurring,unplug one sensor at a time beginning with the Mass Air Flow first,.if it uses one.Many times,not always,depending on the sensor,if the sensor is taken out of the picture as far as what the PCM is seeing,like unplugging the MAF,the PCM will substitute the missing sensor output with a generic value that will allow the engine to at least run,and if unplugging for example the MAF,the engine idle speed returns to normal,you know you're onto the problem.You didn't mention if the engine ran ok other than the idle problem.As far as checking for vacuum leaks,i use something like brake cleaner or WD 40,more of a liquid,and it does sound like a vacuum leak.Plastic intake manifolds do develop nearly invisible cracks that open up more with heat.Revsisit the possibility.And as for the PCM,it is possible,but more likely a mechanical problem.Lastly,remove an O2 sensor or two before the catalytic convertor,run the engine and see if anything changes.Cheap way to verify the catalytic convertor is flowing and not restricting engine airflow,as i have seen bad cats cause misfire codes and strange problems.Good luck.
SOURCE: Car keeps shutting off
I can solve part of your problem. I would check the crakshaft position sensor. These are located behind the harmonic balancer. This will caues the engine to shut off when the engine is at opperating temperature. As for your fluctuating fuel needle, I have a question for you. Do you use Shell gas at all? If you do then their detergents in the gas has eaten away at your fuel sending unit and it needs to be replaced. Only use Esso, PetroCanada (if you are in Canada) or Chevron gas if at all possible. Shell has had dealer bulletins about GM and Dodge not using their gas. The check engine light is usually a faulty O2 sensor but replace the CP sensor first.
SOURCE: Olds Alero sluggish acceleration
Hi
You need to get the cars ECU (cars main computer brain) scanned for fault codes. The symptoms you are having are often caused by faulty engine sensors. The scan will identify which of these are at fault as these faults are retained within the memory of the ECU. This will give you a definite direction on the problem.
Ideally you should ask the dealer to do it as they have the software specific to your car - however your local Auto Parts store will often do this for you for free with a generic scanner. Many of these sensors are easy to change out yourself if you can identify which one is giving the error.
Hope this helps. Please remember to rate my answer. Thanks.
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