VRCobalt

Lately my cars been idling kinda rough. car has 28k miles. dealer cant fix it cuz it never happens when ur in the shop. anyway while im at a traffic light the engine vibrates like it misfires and then is fine when i accelerate. its not all the time. usually last about 5 sec max. since this has been happening. mpg has dropped from 27 to 24. Now when I shift from park to drive or vice versa, rpms jump to about 1300 and then drop to normal.

I thought maybe i should clean the idle control valve, but i dont know where it is. Should i just go get a air induction and fuel cleaning?

Thanks 4 any help

redlineblueline

idle is computer controlled

Jn2

iTrader: (1)

everytng on thi car is fly by wire...whch has its advantages from time to time, ask them if they could re-flash the ecm for you, that might fix it, or better yet, go to autozone, get ur self some microfber towels, and some throttle body cleaner, and clean out ur throttle body, i know i clean my out from time to time to keep it from getting all dirty, trust me, all that crap buids up, you dont even wanna know how black the TB was on my grand am, that thing was black, and remember, our TB's are a gold bronze color, i will assume yours shoudl have some build up on it, just clean it off, try to clean a but more inside the TB too, if you can, take it off and give it a good clean(which is why recomended microfiber towels, they leave less of a mess)

yellowltcoupe22

yeah try cleanin the tb as stated above.. thats what i done to mine when it started to die at idle. fixed it and havent had trouble since then.. just try to keep it cleaned out bout once a year at the least and you should be good to go.

HackAbuse

Clean your MAF sensor

hungryhip-ccp

iTrader: (2)

and throttle body umm take the intake off and open the butterfly with finger and clean were buttr contacts throttlebody and clean maf with brake or carb cleaner dont be scared to use like a 1/4 to 1/2can

yellowltcoupe22

yeah make sure to clean where the butterfly makes contact.. that was the problem with mine.. the build up made it stick closed when i'd let off the gas..

Jn2

iTrader: (1)

ps- autozone now carries a MAF cleaner...its in a spray bottle just like the carb cleaner is, they barely started carrying it, so dont be suprised if some of the workers dont even know they have it, its part of the new planograms we have to set up, so yeah, autozone has that cleaner for it

VRCobalt

The dealer actually replaced the throttle body about a month ago and the MAF was shining. Maybe they cleaned it while replacing the TB. They replaced the throttle body because somehow it was not mounted correctly, which I dont know how because I havent touched it and all maintenance is done at the dealer. The air filter is new, tb is new, maf is clean, plastic intake parts are clean also, no build up whatsoever. The dealer did reflash the ecm. They cant figure it out. They told me that when the idle issue becomes more constant, then bring it back.

What I did notice when I was looking at the new TB is that the plate is not completely closed when the car was off. I can post a pic up later this evening. If I pushed the bottom part of the plate then it would close completely.

Does this help? Its getting annoying that my engine acts up at every stop sign or light.

Thanks in advance

Red07SSNA

Your TB is double spring loaded -- it does not close when the car is off. If you listen to the underhood sounds when you shut off your engine you can hear the TB open after the engine stops. When you turn the key to "off" the TB actually closes all the way to prevent run-on and then it opens a second or two later -- the ECM releases the TB and the blade goes to its' "rest" position (partly open). The idle is controlled by the ECM through the TB -- it moves the TB throttle to keep the idle correct.

VRCobalt

Thanks Red07SS.

Alright with that being said. Does anybody have any suggestions about my issue.

Quick recap on it. When Im idling, the engine vibrates for a few seconds like it was hesitating or misfiring. Will Im driving, everything is fine. Car has new TB, clean MAF, clean intake plastic parts, ECM was reflashed by dealer. Ive used lucas fuel cleaner every oil change since I bought the car new. Im gonna replace the fuel filter this week.

Thanks in advance.

srowler9

I was going to say to check all of the filters. Air and fuel car make the idle run a little rough if they are dirty.

Red07SSNA

Is the engine roughness only at idle? Low speed/low RPM is it smooth? When they replaced the TB did they inspect the gasket/seal or replace it? Could be the fuel filter but then if it was you should notice poor performance overall. Could be a stopped up PCV orifice in the intake manifold. 2.2 intake manifold PCV orifice is a small hole in the center of the manifold -- between the intake-to-head-seals. While the engine is idling put a vacuum gauge on the valve cover nipple for the hose that goes between the VC and intake tube -- you should have vacuum there. If not your PCV orifice most likely is plugged. Any chance that the intake manifold was R+R'd - there is a seal around the PCV orifice and if it's missing that could also be the problem.

hungryhip-ccp

iTrader: (2)

ya know if its just fluctuating a little i would say that is normal, the idle dips and then returns to normal and car shakes a little, that just seems normal to me. do you have any mods? seens how they replaced everthing that we can think of or mention! are you sure your not just looking/litening too hard? i mean the dealer dosent seem to think anything wrong! did you get some shitty gas maybe?

the fuel filter is 80 somthing dollars dealer only.... ouch!

Red2.4SS

Dirty MAF sensor, bad O2 sensor??? Both can lead to poor fuel economy and a rough idle.

hungryhip-ccp

iTrader: (2)

have you or dealer checked/mentioned that that would explain poor economy and rough running while cold, but not all the time just while cold...

Red2.4SS

it says at idle. nothing about only when cold.

Do you mean cold outside, or cold engine?

hungryhip-ccp

iTrader: (2)

that will be linked to b1 s1...

Red2.4SS

when the engine is first started it runs in open loop until the heated O2 sensor is up to temperature. Once the operating temp of the sensor is reached the ECM switches to closed loop mode. It does not take long for the sensor to start working. Well before the engine is fully up to temp.

CobaltCoupeCrazy

iTrader: (1)

If you intend to do this be sure to use MAFS specific cleaner such as that from CFC. Using something other than MAFS cleaner could have you buying a new sensor.

hungryhip-ccp

iTrader: (2)

uhh we have been using brake cleaner at my shop for 5+ years and no problems... but it dosent matter i dont think thats his prob its brand new or just cleaned i cant remember what he said one of the two... now anything that will leave behind an oily residue I WOULD NOT USE

VRCobalt

Hey only at idle. They replaced the gasket. What is R+R'd? And I dont have a vacuum gauge. Any other way to check it? I will look for the PCV orifice this afternoon. Thanks for the help Ill let you know what I come up with.

Actually Autozone has a fuel filter for our balts now. It only costed me $15. As for mpg, they said its the way I drive. Ive havent changed my driving style since I got the car. I used to get 27ci/31hi. Now its 24ci/27hi. 3 miles is 3 miles. That an extra day of driving. And this idle issue isnt normal trust me on this one. As for the O2 sensor, if that was bad wouldnt the MIL light come on?

Red07SSNA

Also check the o-ring seals on the oil fill cap and the oil dipstick.

R+R = removed and replaced or removed and reinstalled.

HO2S would set a code. Dealer would see that.

VRCobalt

What will the o-rings do? Dont they just seal? They seemed fine to me today. I did find some grease in the hose between the valve cover and intake tube. Cleaned that out with some carb cleaner and sprayed it into valve cover nipple and swiped the grease out. Also found grease in the intake piece above the throttle body. Cleaned all that out and heavily sprayed into the throttle body. I also changed the fuel filter. Got it at autozone for $15.

Anyway, engine still hesitates (or whatever the proper term is) at idle. Its not as long as before but it still affects my acceleration. After doin all that, I went to accelerate when light turned green and engine hesitated and didnt accelerate until it stopped hesitating.

Im going to get a vacuum gauge to see if there is any vacuum at the valve cover nipple. in the meantime, does anyone else have any other suggestions?

I thank everyone that's helped so far.

jg123boss

I got an AC/delco fuel filter on ebay for less than $20 works perfect