irregular idle

[black crowe]

Does anybody know what causes this? It bounces between 500-800 rpm. I cleaned MAF and thought that it might take care of this, but did not. I thought i saw were other people have had same problem. If they found a solution(hopefully a simple one, that i can do myself) i would love to hear it. thanks

 

[Importboy]

Mine would do that at red lights when i first bought it. Turned out I bad spark plugs. I replaced all six plugs with Bosche platinums and it runs great now. Hope this helps.

 

[Alec]

How fast does it bounce? It's normal for idle speed to vary sometimes: with weather, driving conditions, incline, engine temp. However, if it's bouncing fairly fast that's not good (obviously). A simply solution might be to reset your computer though. Mine used to bounce when the weather changed greatly, and resetting the computer always did the trick.

 

[black crowe]

Thanks, both of you for help. As far as how fast it jumps, not real fast. Mainly when im sitting in park, it will go 3 or 4 sec at 900rpms or so then drop down to about 600 for a few. Ive already reset my batt a couple of times. Would new plugs be good idea? Its not like its a major thing, but it just doesnt seem normal. Are those plugs easy to get to on 4L? Also which ones are best? Importboy seems pretty happy with the bosch's. Anyway, i know its a lot of questions, but thanks.

 

[KJB]

Try removing and cleaning the Idle Air Control Valve. It's a solenoid valve located on the side of the intake manifold. Remove it and clean it with throttle body cleaner (not carburator cleaner). Good Luck!

 

[black crowe]

Originally posted by KJB
Try removing and cleaning the Idle Air Control Valve. It's a solenoid valve located on the side of the intake manifold. Remove it and clean it with throttle body cleaner (not carburator cleaner). Good Luck!

Thanks bro. Im assuming that it is fairly easy to find and remove. Also, did you mean TB cleaner ONLY? Or just dont use carb cleaner.

 

[01EB5.0]

I would do the IAC first, then go for plugs/wires. I run Bosch +4 plugs and am very happy.

 

[wades94xlt]

my idle was all over the place, and six places looked at me and said I have no idea what's wrong with your rig. Finally I found a guy that knew it was a vacuum modulator in the tranny. Cost me a bunch, but got it fixed.

 

[01EB5.0]

Too bad that isn;lt my problem....I had my tranny replaced a year ago :-( oh well...i'll keep trying

 

[black crowe]

I cleaned IAC last weekend, still rough idle. Next is plugs and wires. If that dont do it, i guess ill throw my hands up and say the heck with it! I dont guess its that big o deal.

 

[01EB5.0]

Originally posted by black crowe
I cleaned IAC last weekend, still rough idle. Next is plugs and wires. If that dont do it, i guess ill throw my hands up and say the heck with it! I dont guess its that big o deal.

I've thrown my hands up...i mean mine only does it twice a month so I don;t care anyway..it runs a heck of a lot better then many other friends cars with less then 116,000 miles

 

[Ross-N-Chicago]

I replaced my Throttle Pos Sensor and put new Jacobs 8.5mm wires/Motorcraft platinums and it has never idled better. Ran some TB cleaner through the upper and cleaned the IAC, replaced the O2 sensor. I truly couldn't believe the difference; it is pure at 750rpm.