Engine Shudder After Hard Stops

[YukonCrazy]

2008 GMC Yukon 5.3 Flex, 2WD, 170K

Twice in the past two days, I had to stop somewhat abruptly. Upon doing this, the engine started to shutter/shake like it was going to stall. Putting it in park stopped this behavior and then it went back to a normal idle. Kind of strange and I am not sure what to make of it.

Either related or unrelated, I also recall a message on the dash that said something like "Service Stabilitrak" after like going over a rough road or pot hole. This turns off after a few seconds.

Ideas?

 

[kbuskill]

Sounds like perhaps a loose ABS sensor. When you hit rough bumps or stop quickly the sensor maybe jostled about causing the ECM to "think" you are loosing traction which then cuts the power of the engine via the ignition (coil packs) causing it to misfire.


This is just a hypothesis.... a Tech 2 scanner would be very helpful in diagnosing this further.

 

[YukonCrazy]

You know after all this time, I actually don't own a scanner, but sounds like it would be helpful in many ways. Should I just search online for "Tech 2 Scanner" or is there something more specific? Or maybe a "GM Tech 2 Scanner" is way out of my budget?

 

[kbuskill]

You know after all this time, I actually don't own a scanner, but sounds like it would be helpful in many ways. Should I just search online for "Tech 2 Scanner" or is there something more specific? Or maybe a "GM Tech 2 Scanner" is way out of my budget?

James @swathdiver Will be able to better answer this question as he has one and usually has a good link to where to purchase from.

 

[swathdiver]

That doesn't sound good Scott, could very well be an issue with AFM but how its acting doesn't make a whole lot of sense. Yes, the Tech2 can see things our eyes and ears cannot and would be most helpful in diagnosing this accurately and quickly.

There are a number of folks selling them new on ebay, just make sure you get the latest PCMCIA card, the 33.004, and decide whether or not you want the case. I like the case.

@Rocket Man recently bought one from a guy off ebay and I think he had a good experience.

 

[YukonCrazy]

Well, for a few years now, it's obvious when it switches back and forth from v4 to v8 mode so I would also question the AFM.