Intermitent Engine Idle Problem

[elmor]

My 2005 LeSabre has started to do something strange when stopped in drive. The first time I was sitting in a drive-thru, the engine started this rump rump rump thing and when I put it in park, the idle went way up for a couple of seconds. I got it parked and shut it off for a few minutes and when I fired it up, it was fine the rest of the day. This has happened about 10 times now and I am almost afraid to drive it in city traffic. Could it be a throttle position sensor? The car drives fine when rolling down the road otherwise. Any input would be greatly appreciated.

 

[DrivenDaily]

Scan it for codes! Without doing that, you're just throwing darts at a board in the dark.

You're bound to hit someone when they walk by, and then you'll both have hurt feelings, then get into a fight, and then get arrested.

Don't get arrested! Scan it for codes!

 

[02LTD2.0]

Check for vacuum leaks, clean the MAF and IAC.

 

[elmor]

Finally got a code reader to try and find out what's going on with my idle. It did not give me a number like I expected but, it did say something about an 02 heater circuit issue. Would a bad 02 sensor cause the intermittent bad idle? I cleaned the MAF sensor a couple of months ago so I don't think it's that. I had to replace the MAP sensor today because the old one fell apart in my hand. That may have been the cause of the whistling I heard on that end of the engine. After the engine warmed up completely, it started the rump rump rump again and stalled at a stop light. I got it fired up and when I came to a stop sign and then went to accelerate, it had no power. I stuck my foot in it and it barely moved. All of a sudden it took off like a rocket. I love this car and it has run so well for me.

 

[DrivenDaily]

Think about it: If the ECM thinks that there is an issue downstream with the oxygen level, it can affect how much fuel is injected. All by itself, that can and will affect drivability, and it'll likely be more noticeable at lower RPMs.

Use the scanner to learn what's being reported as out-of-spec and you stand a better chance of fixing the issue. It sure beats throwing parts at it!

 

[02LTD2.0]

Educate yourself on reading and understanding LIVE data such as fuel trims and MAF readings. YouTube has some good videos on fuel trim theory which can help you to diagnose problems with your engine.