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Discussion Starter #1 (Edited)
UPDATED SEE LAST POST 06 Cobalt Rough Idle/Stall when Stopping or Quick Deceleration

Hello All,

Here is the problem I have.

06 Cobalt LT 2.2l 103065 Miles

When decelerating on the freeway to come to a virtual stop for traffic, when stopping at a stop light, when pulling out of the driveway, or at any point when the RPM's fall quickly to idle speed I have an irratic idle.

Idle will fluctuate between 300-750 rpms

Normal idle is around 750 rpms

This morning it actually stalled when I was pulling up to a stop sign to pull out of my subdivision. It did restart right away.

When the Idle is rought the lights dim on the car, power steering becomes weak, and other problems you would expect when your idle drops and your car is about to stall.

No check engine lights come on at all (I wish they did, I have a nice scantool).

If I decelerate slowly, or have been driving at even driving conditions (not alot of accelerating then decelerating) this doesn't really happen.

Any ideas? Has anyone had this happen?

I just bought this car alittle over a month ago and rely on it so I need to figure this out and get it fixed.
 

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I just had my cavalier worked on to fix its rough idle, when in drive(automatic) it would settle down for a few than start up and i would have to stay in the gas alittle to keep it from shaking. They cleaned up my maf, injectors and things like that so this could be what you have to do to the balt. Has the fuel filter been done since being bought? These are the simple things to get taken care of first. Can be pricey if you have a shop do it but if you do not know how than its the best bet.
 

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ummm...well....wow....first off welcome to yourcobalt.com

second....it could be a number of things...battery, alternator, fuel pump, fuel filter, plugs, coil packs, computers goin bad.


Thats weird man
 

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yea, that is why I said he should look at the simple things like I mentioned. Hate for them to get into some expensive stuff and it be something easy. with that mileage it could be just basic stuff.

yea thats what im thinkin....the car has alot of mileage on it so it wouldn't hurt to change everything. plus check all the fluids too.
 

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^sounds like that would be a good idea to start with. Check the small stuff, let us know if that improves the issue, if not let us know what ended up being wrong. Try the DIY section for some how-tos on these kind of things. I think the section should help you.
 

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Discussion Starter #8 (Edited)
I'm hoping it's not the computers...

I'm going to skip school tonight I think and work on this in the cold dark garage (I hate michigan).

I wish the damn thing would just throw a code already.

BTW my exp is mainly with Nissan 300zx's, Malibu 3.1's (3100), and Vortech 4.3's. I have replaced engines in Astro vans, 300zx's, etc so doing the work isn't gonna be a problem. "Why pay someone else to screw up something I can break on my own"

It's finding the right work to do when there is no engine code.

That said it is a solid car other than this, no leaks, body is perfect, etc. I got it for 50% of the bluebook cost for a private sale/trade in.

I now have two of these (My 06 and my GF's 05, both are white sedans :( ) so I'm sure I will be spending time here from now on.
 

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Discussion Starter #9
Last Night I did spark plugs, 1 and 3 were really bad, 2 and 4 were ok.

I also replaced air filter.

Plus I started running some fuel injector cleaner through the system.

The throttle body is filthy as well as the tube that connects the air intake to the valve cover so I'm going to clean all of that stuff up tonight.

Problem is is so damn irratic you can't tell if you have fixed the right part unless you drive it around several different times in several different coniditions.

Argh it's driving me nuts and on top of that my antenna broke last night so I have to figure out some way to connect the new antenna wire to the old antenna wire or rerun the whole thing.
 

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Last Night I did spark plugs, 1 and 3 were really bad, 2 and 4 were ok.

I also replaced air filter.

Plus I started running some fuel injector cleaner through the system.

The throttle body is filthy as well as the tube that connects the air intake to the valve cover so I'm going to clean all of that stuff up tonight.

Problem is is so damn irratic you can't tell if you have fixed the right part unless you drive it around several different times in several different coniditions.

Argh it's driving me nuts and on top of that my antenna broke last night so I have to figure out some way to connect the new antenna wire to the old antenna wire or rerun the whole thing.
That's more than likely your problem...remove it and use CRC throttle body cleaner. Idle is controlled by the throttle blade on drive by wire cars like your balt....so yea.
 

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Discussion Starter #11
I may have fixed it. It didn't happen on the way to work this morning and it usually does, we will see how it goes for the next week or so. I may have broken something else though, we will see how it goes for the next few days.

Here is was I think may have fixed it.

SO yesterday I subscribed to a TSB site so I could get all the TSB's on the cars as I found a couple that from the titles sounded about right. B IS posted below.

Basically I used CRC MAF cleaner and cleaned my MAF. At the recommendation of several people I used this same product to clean the plastic intake shroud (Before the Throttle body), the Rubber pipe connecting the shroud and the valve cover, and (I'm sorry, I was tired, but this was still stupid even though they said to do it) the throttle body.

Now, It worked great on the MAF and there was several dirt particles and alot of dust is cleaned out of the MAF so I'm thinking this could have been the problem (SEE THE TSB BELOW), however it ran like s**t for about 5 minutes after I got everything put back together and started it up.

It seems to be running ok now so I will have to wait and see how well it all holds up.

I did notice thought now I have was sounds like either a belt starting to go bad, maybe a vacuum leak (higher pitch kinda soft whinning sound).

However like I said this morning it didn't do the dropping to 300rpm and almost stalling when I decelerated. We will see over the next week if this truly fixed the problem or not.

Here is the TSB and pay close attention to it if you run a CAI, I don't but my air filter was freaking filthy.

Bulletin No.: 04-07-30-013B

Date: February 01, 2007

INFORMATION

Subject:
Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter

Models:
2007 and Prior GM Cars and Light Duty Trucks
2007 and Prior Saturn Models
2003-2007 HUMMER H2
2006-2007 HUMMER H3
2005-2007 Saab 9-7X

Supercede:

This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle).




The use of an excessively/over-oiled aftermarket, reusable air filter may result in:

Service Engine Soon (SES) light on

Transmission shift concerns, slipping and damaged clutch(es) or band(s)

Engine driveability concerns, poor acceleration from a stop, limited engine RPM range

The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur.

When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern.

The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.

If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs.

Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items.



I'm wondering if because my MAF was dirty it wasn't adjusting to the change in air flow, when I decelerated, fast enough causing the rough idle.

PS if you need to read a TSB, need blown up part diagrams, etc, let me know.......
 
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