2010 2SS Engine Bucking

[MickGIS]

Hey,

My 2010 2SS has an intermittent problem; the engine bucks under any load and in any gear. By bucking I mean that the engine seems to stall for a fraction of a second then returns to running normal. When this happens the analog speedometer drops to zero with the dash lights behind it momentarily come on and occasionally in the center display the Service Stabilitrak flashes (the one with the wrench icon)
The digital speedometer remains normal displaying the current speed, the tachometer reflects the bucking by dropping a few RPMs. All the other gauges are unaffected.
No CEL code is thrown.
It can run for hours with no problem or buck several times a minute.
At first I thought it might me dirty fuel injectors or a faulty MAS (which I cleaned anyway) but no CEL code and the weird behavior of the analog speedometer pointed elsewhere; probably electrical.

Its been to the dealer twice and they've had it now for the third day. I just got a call from the dealer and they said that it looks like a data line problem and they are waiting for a call from GM.

What is a data line problem?
Has anyone else had a similar problem?
What did you do to fix it?

Thanks,
Mick

I also posted on Camaro5.com, LS1Tech and ModernCamaro.com

[JerTM]

A data line is an electrical circuit that modules use to communicate.

[MickGIS]

Originally Posted by JerTM

A data line is an electrical circuit that modules use to communicate.

Makes sense, thanks.

Dealer called back and said GM had two places to look under the dash for this type of problem and they both checked out good. The dealer said he's going to have to start charging me hourly to trace down the lines and figure out which one went bad.

[JerTM]

Originally Posted by MickGIS

Makes sense, thanks.

Dealer called back and said GM had two places to look under the dash for this type of problem and they both checked out good. The dealer said he's going to have to start charging me hourly to trace down the lines and figure out which one went bad.

Unfortunately straight time is necessary on some electrical jobs. Intermittent conditions make it very difficult to track down, and can take a lot of time. If it was broken all the time the tests would show it much quicker. Good luck.

[MickGIS]

Just got back from the dealer where I spoke with the Service Advisor and Service Technician about my 2010 2SS with the intermittent engine bucking problem.
They said:
1.After several hours labor they could not find the explicit source of the problem.
2.GM offered a few places to look for the problem, which the Tech did but did not find any issues.
3.GM has limited experience with this specific issue on a Gen5 and not much more technical advice.
4.Tech said he traced the data lines as much as he could (did not find any obvious source of the problem) but that he could not see between the engine and the firewall (without pulling the engine) nor in under the center of the dash.

Discussed with the Service Advisor and I have two options:
1.Pay ≈$500 for the hours already invested and drive away without a resolution. The Tech said that maybe with his testing, moving stuff around and reseating connections it may have fixed the problem. They will reassemble what they took apart (part of the dash, glove box, rear seat) for no additional charge.
2.Pay ≈$1800 for the Tech to build/install a new harness for the data lines. They said this had an ≈85% chance of success. I consider this percentage a SWAG (Scientific Wild Ass Guess)

I will ponder what to do over the weekend and let the dealer know how to proceed on Monday.

Anyone have any suggestions or advice?

Mick

[MickGIS]

Laura over on Camaro Club of the Rockies said that she had something similar happen and it turned out to be a bad fuse. Maybe I should ask the dealer to replace all the fuses and test, sounds reasonable to me. What do you think?

[MickGIS]

Dealer said the Service Tech checked the fuses and fuse box and found no problems. So going to have them fabricate and install a new Data-Line harness.

[MickGIS]

Picked up my Gen5 this afternoon after the dealer rebuilt/installed a new data line harness and ECM. So far so good with no bucking, but time will tell.
By replacing the ECM I lost the dyno-tune but the tuners saved the tune and will reload it on the new ECM. I think I'll drive with the stock programming for a week or so before I get the tune reloaded.

[MickGIS]

• 07/03/2018

o Picked up Gen5
o No bucking on drive home
o No CEL

• 07/04/2018

o Took for test drive
o No bucking
o CEL came on after several miles, 5 or less.
o O'Reilly Auto Parts (So Holly) tried to read CEL but could not sync.
Afterward:

1. CEL light still on
2. Brake warning was displayed behind the analog speedometer with audio warning. After several seconds audio warning stopped but Brake still displayed.
3. (( ABS )) displayed behind the tach
4. Swerving Car icon displayed behind tach

o Drove a few miles
o Advanced Auto Parts (County Line) successfully read CEL codes

1. P0430 – Catalyst System Below Threshold Bank 2, an expected code related to the O2 sensor on the High Flow Catalytic converter
2. U0073 – Control Module Off
3. U0109 - Lost Communication with Fuel Pump Control Module (FPCM)
4. After engine shutdown and restarted only CEL light remained. None of the other three lights were displayed: Brake, (( ABS )) and Swerving Car

[JerTM]

Sounds like the original issue is still present. I suspect a poor connection with the power, ground, or comm circuits to your fuel pump control module are the culprit.

[frankwjr]

whew! $1800 and still problems...seriously sux....please tell me it has a new(er) battery? good luck!


peace

[Avenging Orange]

Originally Posted by frankwjr

whew! $1800 and still problems...seriously sux....please tell me it has a new(er) battery? good luck!


peace

[MickGIS]

Originally Posted by frankwjr

whew! $1800 and still problems...seriously sux....please tell me it has a new(er) battery? good luck!
peace

Yes, had them install a new battery and negative cable.

[JamesMyBoy]

Here's my two cents worth:
Plug wires
Had the same symptoms many years ago, on a pickup truck, but sure sounds similar.