2010 Impala - Scary Stalling Issue at 55-60 mph

[djrobnyc]

I'm looking for some help in diagnosing an intermittent (but potentially dangerous) problem that I've had with my 2010 Impala that has about 40,000 miles and the 3.5L engine (it's an LT).

About two months ago as I was driving on a local highway -- about 55-60 -- I felt a slight hitch and the Service Stabilitrak lamp/message lit up. I continued to drive another mile or so at this speed - and then the Starting Disabled Service Throttle and Engine Power Reduced messages came on, as well as the Service Engine Soon lamp. The car slowly shut off -- but I made it to the side of the road. The car would not restart for 2 minutes - I was then able to restart it and it drove okay, but I pulled over to a safer part of the road, called GM and they had the car towed to the dealer where I purchased it from.

The shop told me the car spit out a Throttle Body code and that part was replaced. They kept the car for two days to test it and the problem seemed to have gone away.

Unfortunately, that was not the case. This same thing happened the other day. Everything happened exactly the same. However, this time - after I got the car started after 2-3 minutes -- I drove it to work, which was a few miles away. At the end of my work day, the car started up fine and the Service Engine Soon lamp was NOT lit. I drove the car back to my dealer - and they have it now.

This time, they tell me the car spit out a Low Voltage code - which they traced to the battery. They tested the battery, it failed that test so they've replaced it. Again, they have kept the car for two days for further testing - and called GM to tell them about the problem. I questioned the shop as to whether this was really the problem part (the battery);they seem to think it is.

While I appreciate the effort by the dealer - I do feel they are really trying to find out what's wrong - I'm a bit skeptical.

Can anyone out there help? It's not fun to try and have to navigate getting to the shoulder of a highway while going 60 mph to 0. And my wife won't get near the car now...

The only other piece of evidence I can offer is that both times this happened there was less than a quarter tank of gas in the car.

By the way, I've read on some other sites of people having this same issue - one person even said her throttle body was replaced, didn't fix the problem (same as happened to me), but when she brought it back, the mechanic replaced the accelerator pedal assembly sensors/accelerator pedal position sensor.

I asked the dealer mechanic about this and I believe he said those sensors are part of the throttle body - and were therefore replaced last time.

Again, thanks for your help!

[maxwedge]

Ifthis only happens when the fuel is low someone should check fuel pressure on a long term test basis of course this is tough to do as the fuel press gages do not reach into the car, no one here is going to solve this only onsite diagnosis will work, does the shop know this only happens when fuel is low? When those mentioned sensors fail the pcm goes to limp mode and the car can be driven at low speeds.

[GMCustomerService]

Good morning djrobnyc,
We're sorry to read about this situation with your Impala. If you would like for me to open up a Service Request on this, please send me the following information via private message: your name, phone, address, the last 8 of your VIN and current mileage, and the name of your involved dealership.

All the best,
Sarah
GM Customer Service

[danielsatur]

Any electrical signal lost on a Drive-by-wire system, can trigger a Limp mode.
Does weather, or water play a factor?
Did the shop do a full Power down on the EBCM?

We have seen both broken signal wires, and bad electrical connectors on Electrical Controlled Throttle bodies.
See AF www.automotiveforums.com/vbulletin/showthread.php?t=974347
AF www.automotiveforums.com/vbulletin/showthread.php?t=975140

Yes - If a Limp/Fail safe mode is triggered, it's a 35mph-70mph accident in rear waiting to happen!

If any Automobile manufactures are interested in a safer solution for a Safer Drive-By-wire system, please conatct me ASAP.

[danielsatur]

www.caradvice.com.au/188175/kia-sorento-out-of-control-in-us-takes-woman-on-wild-ride/

reckless endangerment, speeding, bad 911 calls, and almost crossed state lines.

If True, why wasn't the Drive selector put into Neutral?

Nonfiction Kia story, there's no acting or drama see AF www.automotiveforums.com/vbulletin/showthread.php?t=1080948

[Tech II]

This time, they tell me the car spit out a Low Voltage code - which they traced to the battery. They tested the battery, it failed that test so they've replaced it. Again, they have kept the car for two days for further testing - and called GM to tell them about the problem. I questioned the shop as to whether this was really the problem part (the battery);they seem to think it is.

Two year old battery problem, with no problem cranking the vehicle and no red BAT light on? I tend to doubt it......what was this low voltage code, should be on the repair order? Low voltage could be caused by a bad connection, due to a voltage drop...

While I appreciate the effort by the dealer - I do feel they are really trying to find out what's wrong - I'm a bit skeptical.

Can anyone out there help? It's not fun to try and have to navigate getting to the shoulder of a highway while going 60 mph to 0. And my wife won't get near the car now...

The only other piece of evidence I can offer is that both times this happened there was less than a quarter tank of gas in the car.

Low fuel would not set a TAC code or low voltage code.....

By the way, I've read on some other sites of people having this same issue - one person even said her throttle body was replaced, didn't fix the problem (same as happened to me), but when she brought it back, the mechanic replaced the accelerator pedal assembly sensors/accelerator pedal position sensor.

I asked the dealer mechanic about this and I believe he said those sensors are part of the throttle body - and were therefore replaced last time.

If the tech said that, he doesn't know what he is talking about.....those sensors are on the accel pedal, not on the throttle body(TPS is part of the throttle body.....the APPS is part of the accel pedal)....