Intermitten rough idle after braking - 2007 Equinox 3.4L

[jmcelhany]

Hello All,

Long time reader, first time poster.

I have had the Equinox for four years with little to no issues, aside from plug/wire issue that was fixed with a tune-up; the vehicle currently has 90K miles and has received all scheduled maintenance.

To get to the short of it, the car is a daily driver for my wife. It starts/idles fine from a cold start and no issues noted upon acceleration; however, at random intervals and after braking (in some instances sudden/rapid deceleration), the engine idles very rough and tries to lurch (assuming misfire). Occasionally after the misfire issue, a message note "Service Stabiltrak" is reflected on the control panel and disappears after time. I have checked all plugs/wires and re-seated them w/ new grease.

Today, I visited a local part house to have the codes checked. Their reader returned as an error, something along the lines of "data stored but unavailable"; the error was indicated to be related to ABS.

After thought, I am of the conclusion that it's not a fuel delivery/spark issue given the random intervals. I am assuming that since this only happens after braking, it may be a timing/fuel position sensor issue. Has anyone ever heard of this happening or have any suggestions?

I intend to disconnect the battery tonight and force the vehicle through diagnostic relearning, in hopes of solving the problem. After that, it's going to the dealer (under power-train warranty until 100k).

Any help is appreciated.

Thanks.

[Ruley73]

Originally Posted by jmcelhany

Hello All,

Long time reader, first time poster.

I have had the Equinox for four years with little to no issues, aside from plug/wire issue that was fixed with a tune-up; the vehicle currently has 90K miles and has received all scheduled maintenance.

To get to the short of it, the car is a daily driver for my wife. It starts/idles fine from a cold start and no issues noted upon acceleration; however, at random intervals and after braking (in some instances sudden/rapid deceleration), the engine idles very rough and tries to lurch (assuming misfire). Occasionally after the misfire issue, a message note "Service Stabiltrak" is reflected on the control panel and disappears after time. I have checked all plugs/wires and re-seated them w/ new grease.

Today, I visited a local part house to have the codes checked. Their reader returned as an error, something along the lines of "data stored but unavailable"; the error was indicated to be related to ABS.

After thought, I am of the conclusion that it's not a fuel delivery/spark issue given the random intervals. I am assuming that since this only happens after braking, it may be a timing/fuel position sensor issue. Has anyone ever heard of this happening or have any suggestions?

I intend to disconnect the battery tonight and force the vehicle through diagnostic relearning, in hopes of solving the problem. After that, it's going to the dealer (under power-train warranty until 100k).

Any help is appreciated.

Thanks.

I'd be prepared for a bill from the dealership. The powertrain warranty is 5 years (from the date of manufacture) OR 100,000 miles - whichever comes first. So it may no longer be under warranty if it was built in late 2006 like ours was. With that said, the worst they could do is charge you a diagnostic fee which is usually around $50-$80 depending on the dealership. At least then you might know what's wrong with it.

Since it only seems to occur when you brake, I would definitely suspect a vacuum leak. Before you take it to the stealership, I'd check a few simple things.

On this engine there really isn't much to check for with regard to vacuum leaks since there are only a couple vacuum lines.

- Check your air filter and make sure is it fairly clean.
- Check the air intake tube and make sure the clamps are tight.
- Finally, check the vacuum hose going to your brake booster.

It doesn't take much to trip the "Service Stabilitrak" message. It will be turned on if the computer detects anything that could remotely cause the Stabilitrak to not work correctly or as good as it should.

Heck, replacing the EGR valve stopped that message from coming back on our Equinox. The EGR valve was in fact bad and triggering an EGR-related troublecode which was causing the check engine light to turn on.

[GMCustomerService]

I see you've gotten some great feedback, jmcelhany. How did the disconnection fo the battery turn out?

If you do decide to work with a dealership and would like assistance, please send me a private message and I will see how I may assist.

Best,
Sarah
GM Customer Service

[jmcelhany]

The battery disconnect/reset had no effect.

Does anyone have other suggestions?

Thanks.