bouncing rpm's at idle

[boostedprotege]

ok so comin home todaye and gettin out of my car i notice that the rpms started bounce from 800-1500rpms. so turned off car and restarted and after a few seconds of being on it goes right back to doing it. the weird thing is it drives fine no cel and it stops when i press the clutch.. looked for vac leaks and couldn't find any. anyone have any suggestions?? i doubt its the egr valve but i will be cleanin that tomorrow to see if it fixes it. so any and all help wud b great

 

[03MSP-JH]

you should sea-foam it. did it to mine and, now it idles pretty good..

 

[boostedprotege]

sea foam the eengine?? how do i go bout doin that

 

[03MSP-JH]

i think theres a HOW-TO thread about it somewhere. there are different ways. i just stick the brake vacuum line in a cup of sea-foam (with the engine running). slowly feed it through the line (or the engine will shut off). once you used about 1/3 of the sea-foam bottle, turn off the car more 10-15min. (to let the sea-foam work). then start it up and rev the car till your exhaust stops smoking (its the seafoam exiting the engine lol). and thats that i would find the how-to thread for better info.

 

[boostedprotege]

Ok guess i'll haveta try it out tomorrow. but what really gets me is it only does it at idle when the clutch isnt pressed in. i have a feel its a sensor maybe and o2 idk

 

[BlkZoomZoom]

Remove and clean IAC. If it doesn't fix it, which it probably won't, buy a new one.

 

[boostedprotege]

Ok so update i went ahead and went to autozone n had them run a diagnotic n one code was pulled its a P0850 code which is neutral switch circuit fault... is this what cud be causin the boucing rpms at idle?

 

[P-Funk!]

No. it just means you can't start the car in neutral.

 

[boostedprotege]

hmmm wudnt that switch only affect an automatic?

 

[Canadian-ES-GT]

Same problem but now its gone!

I had this exact same problem with my 2001 Protege 2.0. It happend while I was dressed as a banana for halloween. It started bouncing in between 500-1100 rpm when idling after around 10minutes of driving. When coming back from school it went away but the funny thing is that I never repaired or touched my car. During the problem, my car had alot of trouble starting and the check engine went on ones. Since then, I just got a couple cases of rough idle which lasted no more then a minute. Never realy found out what was wrong but it works fine now!

 

[slavrenz]

I had this exact same problem with my 2001 Protege 2.0. It happend while I was dressed as a banana for halloween. It started bouncing in between 500-1100 rpm when idling after around 10minutes of driving. When coming back from school it went away but the funny thing is that I never repaired or touched my car. During the problem, my car had alot of trouble starting and the check engine went on ones. Since then, I just got a couple cases of rough idle which lasted no more then a minute. Never realy found out what was wrong but it works fine now!

This seems slightly irrelevant

 

[Randy-]

its your Nuetral Safety Switch, i had the same problem.. car idles just fine now after replacing it. so try and look for the neutral safety switch, do you have any CEL's come up since the Fluctuating Idle? pick it up for 53.99 from autozone... or nappa had it for 39.99. Manual Nuetral Safety switch = 39.99 nappa and if you have a automatic it was 46.99


Here is a CEL that i pulled from mine.
P0850 (http://www.justanswer.com/view_image..._110583712.gif)

 

[boostedprotege]

so that cud cause the idleing problem??? thats p0850 is the only code that came up so i guess i'll be lookin for a switch tomorrow. and no i have 5speed which is y i wudn't think the neutral switch wud have affected that.but i guess since its goin out thats causin the ecu to act funny while its in neutral with out the clutch pressed in..

 

[boostedprotege]

This seems slightly irrelevant

i think he added that becuz it made it all the more embarassing when he stopped next to people and his car wud be reving up on its own causing people to stare at this crazy banana guy hahaha

 

[dkarthik]

I had the problem a while ago... turned out to be my ignition coil. It goes away and comes back, till it finally gives out, I would check that too.

 

[boostedprotege]

i doubt its my coils cuz if it was i wud have problems misfiring while driving also no jist at idle while in neutral and wudnt i be pullin a misfire code. the neutral safety switch does make sense but only one way to be sure

 

[ALPACCINO]

i did a engine swap, i have the b5 dohc, it came from an automatic mx3. it still has the automatic computer an loom. I taught it was that the engine is not properly grounded, sorry i can't offer any help but i too have the same problem.

 

[boostedprotege]

are you pullin any codes?? u might just have the egr problem

 

[Randy-]

telling you call Autozone they have a switch for 53.99 guessing thats a decent price. but yeah if that fixed my problem i had the same problem you did. just replace that. labor for mine to be replaced was around 90 dollars or so..

 

[boostedprotege]

i called em already wont be hear til monday and damn bro you cuda jist did it yourself its easy right on the bottom of the tranny like two bolts thats it like a 5min job lol