idle control system problem on a 2.2L 1996 cavalier

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i'm having a problem with the idle of my car right now. The rpm is alternating high and low while on idle and works fine when it running. the problem started after i replaced to of my fuel injectors because of leacks. on the process i cleaned up the upper manifold asm of my injection system. when i got the car to work i noticed that the idle is messed up. and the obd II shows pg507 idle control system problem rpm higher than expected. i thought that happen because i tighen my idle control (had to do that otherwise car won't start/stall). the possible problems that i learned are:

-Vacuum leaks
-iac malfuction
-or iac wiring malfunction

i checked vacuum problems and i am 85 percent sure that its not it.
i replace iac with new one and run it for about 15 mins and it didn't solve the problem
i checked the wiring "visually" and it looked like in good working condition

what i'm wondering now is that if it's possible that my idle problem is related to my 2 new fuel injection which are the better ones on sale on NAPA. please help

posted by  realholdem

These Cavaliers appear to be a problem child.

Why didn't you just replace the O rings on your existing injectors?
Are the new injectors rated for the same duty?
How's the oxygen sensor holding up?
Is your intake air temp sensor the correct resistance?
Do you have air bottling around your coolant temperature sensor?
Is the TPS adjusted correctly?
Is the throttle plate gummed?
Is your air filter clean?
Is your fuel pressure correct?
Do you have moisture condensing at your tail pipe?
Are the plugs showing signs of distress?

posted by  Wally

just for my own knowledge wally,what would tail pipe condensation indicate?

posted by  carlos

Well hydrogen and oxygen byproducts normally combine to form superheated steam in the exhaust. There's a lot of steam produced per litre of fuel. So you know that to condense it's surroundings must be at the vapour dewpoint temperature. When you overfuel you lower your EGT through latent heat of vapourisation occuring in the exhaust, get it low enough in a pressure environment and the moisture will condense.

posted by  Wally

Thanks for responding.

Why didn't you just replace the O rings on your existing injectors? i broke them trying to pull them out.

Are the new injectors rated for the same duty? i went to NAPA and it is the right part. and it supposed to work. i don't know if collaborating those 2 new ones with old ones will affect the performance. could it?

How's the oxygen sensor holding up? two sensors on the upper vacuum manifold are intact and assuming on working condition.

Is your intake air temp sensor the correct resistance? i'm not sure

Do you have air bottling around your coolant temperature sensor? no

Is the TPS adjusted correctly? my manual says it not adjustable ang i'm assuming its working right

Is the throttle plate gummed? not really. it looked fine

Is your air filter clean? yes

Is your fuel pressure correct? haven't checked yet

Do you have moisture condensing at your tail pipe? i can smell some wierd unusual essense that it didn't have before i had the idle problem. smells like a sewer of some sort

Are the plugs showing signs of distress? not. all cylinders are well as reflected by the plugs

thanks for replying. what do you think wally?

posted by  realholdem

Could your odor be EGR or catalytic converter related?

posted by  PTT1

Did it cure itself?
:banghead: Will we ever hear whats happened? :sleep:

posted by  chatterbox brit

no, are you joking? :screwy:

posted by  Mk3golfer

my bad... :doh:

posted by  Mk3golfer

how about fuel pressure regulator. is this significant to bad idle. i had to adjust (tighten) the idle of the my car to keep it running. i don't have any means to check my fuel pressure. does this makes sense though?

posted by  realholdem

You know when I typed the post, I said to myself that sure as a gun someone will raise that issue. But I figured I would leave the door open for further explanation should someone be concerned. So you were correct with one of your comments. :wink2:

posted by  Wally

i'll try that and let you guys know what happened. thanks

posted by  realholdem

the obd 2 system shows p 507 code. which stands for idle control system failure, rpm higher than expected. also sometimes when i'm run from stopping for stop sign. it feels like the car is not following my pedal, then it will eventually respond to my gas pedal. but only happen within 3 sec. i don't know if this is significant to the fuel regulator. i checked my vacuum system it seemed that their ok. my iac is fine. and there's no vaccum leaks. this problem occured after i replaced my 2 fuel injectors, and crean my upper vacum manifold from carbon build up.

posted by  realholdem

i also noticed. that my engine startup is a little bit not as fast as it was.

posted by  realholdem

Quote:
Originally Posted by realholdem
the obd 2 system shows p 507 code. which stands for idle control system failure, rpm higher than expected. also sometimes when i'm run from stopping for stop sign. it feels like the car is not following my pedal, then it will eventually respond to my gas pedal. but only happen within 3 sec. i don't know if this is significant to the fuel regulator. i checked my vacuum system it seemed that their ok. my iac is fine. and there's no vaccum leaks. this problem occured after i replaced my 2 fuel injectors, and crean my upper vacum manifold from carbon build up.

My thinking is you have cleaned out carbon build up which is allowing more air past throttle plate, idle valve has lost idle setting, is it possible to check and reset throttle position switch?

posted by  chatterbox brit

that make a whole lot of sense to me. however when i put a new idle air control valve on it, it acted the same. thanks for the tip though.

posted by  realholdem

have you ever replaced the PCV vlave?

posted by  carlos

Yes but fitting a new idle air control valve does not reset the idle itself, you need to follow a set procedure to reset the idle, the throttle plate in a cetain position, the TPS sending the correct voltage for the idle position, it needs to know that the engine is warm from the temp sensor, if its in drive, if headlights or other current grabbing items might be switched on, that the mass air sensor is showing idle and so on, then the ecu will control the IACV, it needs to have the correct set of parameters to follow. ie: a set voltage from throttle position switch to tell it to idle. :smoke:

Sorry I do go :sleep: on sometimes

posted by  chatterbox brit

is this a MAP manifold absolute pressure sensor or an mass air flow sensor?

The MAP sensor gets it's signal from the manifold vacuum, the mass air flow sensor gets a signal from a hot wire(usually a platinum hot wire)


If this cavalier has a TPS throttle position sensor then here is something to know. There is a mode that is triigered when the air flow sensor malfunctions. The computer then swithcheds over to the TPS sensor

Run out o time

posted by  cargrime

chatterbox brit was right about AIC valve. i replaced with a new one again and it solved my idle problem. Thank you every one who participate for this situation. my pcv valve is new by the way.
conclusion: car idle is bad, alternating rpm (high,low, high....) on idle, could be a possible Idle air control valve, vacuum leak, and etc. if the problem is related to the Idle control valve, don't just replace the part. make sure that computer will be reset not by just unhooking the battery, but to reset it with a computer through your obd II system. and readjust the idle rpm to 6500 if you messed with it.

posted by  realholdem

WHAT? readjust it to 6500? you planning on people driving around with their engines running on red-line or even over it? I think you ment like 500-800 not 6500

posted by  Golddragoner

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