99 malibu idles roughly when stopped. need advice before I take it to the mechanic

[grommit9]

I am bringing my Malibu in on Thursday to hopefully take care of the idling problem I have been having. When I am at a stoplight and the car is not moving it idles at about 600 rpms but will hiccup to 400 and then immediately back up. The check engine light is not on and the car has only stalled on me once in the past month and a half. Has anyone experienced this problem or might know what would be causing this. I am concerned about the driveability and if it will just die on me one day. There is only 105k miles on the thing. I have heard that there are problems with the IAC and even some of the sensors that might mess up the fuel flow. Would greatly appreciate any knowledge on what the problem is.

[johnschmitt]

V6? If not, ignore the parts referring to your non-existant spark plug wires.

A few things I'd start with:

If it has the original spark plugs and wires that is definately worth a try before taking it in. It's about time anyway. Be sure you get ac delco plugs and good, quality wires.

Pull the air intake hose off the throttle body, get a can of throttle body/ intake cleaner, and do some scrubbing.

Replace the air filter.

Run some techron or some other kind of fuel system cleaner through the tank.

Get a can of seafoam and fog up the neighborhood. (there are explanatory threads on it around here)

[Speedy_1234]

Well, For the spark plugs I would go with bosh platium. The are better plus you don't have to gap them at all. Also I was wondering pop the hood open and turn the car on check if you hear any vacum leak. Also check the pvc value if it still good to check that just take it off and shake it if it rattle then it working. put it back and follow where that vacum goes it should stop in the front of the intake and check if there the plug is still good becuase my car would do the same and it was only that plug that was causing it to idle down to a shuddering stop.

[johnschmitt]

I tried the bosch platinums and had to replace them after about 20k miles. From what I understand, they are designed for a shorter spark than the coils throw out so they heat up and misfire all over the place after a while. They may not be the better plugs, but the ac delcos worked better for me.

Agreed on the pcv valve and checking for vacuum leaks. Several easy ways to find a vacuum leak. Put a short hose in your ear and look for a sucking sound with the other end, get a wet sponge under there and look for bubbles, or blow smoke in there and see if it gets sucked in anywhere.

[Speedy_1234]

Well, I had AC delco Spark Plug in mine i notice when i got to a complete stop the car would idle under 500 rpm when it was in netural the car would be fine What I decide to do is check the spark plugs and i notice that they had crack I think cause of the heat well, anyways when i had those " they said" that those spark plug would help you in to use less gas and i was like yea right i spend more gas with those then the bosh and also the car would not idle uder 500 rpm

[johnschmitt]

...what?

[niccaleb112602]

Mine did the same thing, I lived with it for a while till is started doing it going down the road. Finally after awhile the check engine light came on. It was the well known camshaft sensor. It is located under the power steering pump. First thing I noticed was the wires going into the sensor were fraid. Then when I pulled it, it had a huge thermal crack down the sit of it.

[molhannah]

First thing I would do is go to Auto-Zone and have them run the codes at no charge. If it is a sensor or spark it will have a code stored in the ECU.

[67chevypickup]

your egr is clogged or unplugged from the wiring harness