Huge hesitation, mechanically inclined. Please help

[Brian Wilson]

Ok, I see it is a knock sensor code. It must be because of the outrageous piston slap that plagues every 6.2. I knew something was messing with my timing. I'm already glad I got the autcoal because I threw the code when I was doing my 'spirited driving' to send to blackbear. Now the question, what do I do now? I know I have bad piston slap. I have a 6.2 with 230k miles waiting for rebuild on a stand. Should I replace the sensor (s) or ask for them to be tuned out?

 

[Rocket Man]

That seems to indicate a problem with the knock sensor circuit.

 

[M3kanic]

I am sure if you ask blackbear for their recommendation they will be more than helpful. They also have a ton of experience with these types of issues.

 

[Rocket Man]

Agreed, I'd ask Blackbear for their recommendation.

 

[Brian Wilson]

I was told by soooo many people that these engines were equipped from knock from the factory. And that it would never effect the longevity of this wonderful engine.

 

[Brian Wilson]

I now realize that all these people were GM employees and trying to sell a car.

 

[Rocket Man]

I'm not sure what exactly you're complaining about. Good luck with whatever you decide to do.

 

[Brian Wilson]

Honestly, there are only a few things that can pull timing like I measured. And I missed it. I'm pissed at myself for missing such obvious crap and bothering a great community. I feel like a noob.

 

[Chip18]

Hmm you seem to have "access" to some pretty high tech gear??

On the "Brakes" ... The knock off "Mighty Brake" from "Harbor Freight" 39.00 bucks would get you through this ... but "apparently" it's a "POC" and will break after a few uses.

The "Knock Sensors" issue?? That's interesting?? Most likely it's just incidental to the issues your having?? I don't know how it works on theses engines ... but in general ... if you add a "knock Sensor" monitor to an engine you have to "calibrate" the sensor to the background noise of the motor.

It could be that you have a bad Knock Sensor "also??" Might be worth further investigation on the sensor??

 

[Brian Wilson]

It's cheap and easy to get to. I'm going to change them out and yes the snap on tool has a calibration feature for them

 

[Brian Wilson]

So done with this issue. I will post my solution when it is found. With the high miles im just going to build a new motor for it in my spare time.

 

[Speck]

I wish I had useful info to help your situation. Sounds like you've been covering all of the options. Best of luck with building a new 6.2. Sure is reassuring with you having that high of mileage and just starting to have an issue. I hope you're able to resolve it soon.

 

[retiredsparky]

If the traction control system is activating the brakes (your post about seeing pressure from the bleeders), shouldn't you focus your troubleshooting in that area. I have been watching your logical process, you have pretty well covered the engine related components. Building a new motor will perhaps be therapeutic, and certainly will give you more power. But if the sensors and or module for the traction control are malfunctioning, having more power will not make you go any faster.

I have never messed with the T.C. system, but as smart as you are, you may be able to figure out how to check it. There should be some sort of gyroscope device that monitors angular momentum. The abs sensors probably play a role as well, comparing wheel speeds, that way a separate set of sensors would not be needed. There is a sensor on the steering shaft under the dash, I believe, that provides information about requested steering angle.

Traction control basically limits engine power, applies brakes as needed and screws with your mind. Government goals all accomplished.

Can you disable your traction control by pulling the fuse? Pushing the switch to disable the traction control may not turn it off, if it is malfunctioning!!!

Good luck,
Larry

 

[Chip18]

I now realize that all these people were GM employees and trying to sell a car.

LOL.

 

[Brian Wilson]

A sensor to measure steering angle, gyroscope to measure momentum?!? I really hope you are messing with me. Surely to god these don't exhist in my car

 

[Brian Wilson]

Good info larry. I did pressure bleed them and so far no problems. Been a few days. I didn't want to post that it was fixed until I knew for sure. I also filled up with some 107 octane fuel after the knock sensors didn't fix the timing issue. Still retarding the timing just as much. And since I already pulled the top of the engine apart a month ago I know it's not valve train noise. Has to be piston slap I figure. I doubt a forged rod bent in a stock engine that has never been pushed hard. That's why I'm building a spare engine. I'm going to ask blackbear to tune out the knock sensors or at least make them a lot less sensitive in the meantime.

 

[Chip18]

Well there is certainly no harm in "walking away" when you come up against a wall.

A sensor to measure steering angle, gyroscope to measure momentum?!? I really hope you are messing with me. Surely to god these don't exhist in my car

Yes ... yes they do! If the system "thinks the vie is outta control ... it cuts power and applies brakes to regain stability.

Most likely you would not be checking "stuff" that you don't realize is there.

Maybe ... you have multiple sensor failure/issues that combined to be a major "PIA???" The "Piston Slap think in these motors 6.2?? (Gotta check on that one) is pulling power?? A fault/ or over sensitive "Knock Sensor???" It sounds like the BB Tune maybe able to help you there."

Speculating here ... but disabling systems individually may help you isolate the failure?? Disable the knock sensor and run "Premium" and see if there is still a loss of power?? Disable the "TC" and see if the brakes are still dragging??

I don't know how to disable those systems but it makes sense in my head. But if it's not the motor??? But is infact a system failure somewhere in the vehicle?? A rebuilt motor won't solve the issue and ... that would suck!!!

 

[Brian Wilson]

I agree. It would. I hate to say the brake issue is "fixed". But it looks like it was just air in the abs motor. 3 days and zero drag. But the timing is definite being retarded 30 degrees at times. It threw a knock sensor code finally. Replaced the sensors and calibrated them with a proper computer. Still got a knock code after 5 minutes of driving. I understand this thread makes me look kinda dumb but, I'm pretty good at troubleshooting and systematically eliminating potential issues. Usually. Short of pulling my engine and taking it apart, tuning out the knock sensors is my best tool to eliminate 'knock' as the problem.

 

[Brian Wilson]

I used the 107 octane to eliminate detonation as the cause of 'knock'. And I know I don't have any misses. Finally, I feel like I'm down to my last possible cause for the issue. If not, I will admit defeat, keep paying my full coverage insurance and pray my 0 Guage stereo wire doesn't short out next to a 2 gallon plastic gas can where my subs used to sit. >8-D

 

[Chip18]

I agree. It would. I hate to say the brake issue is "fixed". But it looks like it was just air in the abs motor. 3 days and zero drag. But the timing is definite being retarded 30 degrees at times. It threw a knock sensor code finally. Replaced the sensors and calibrated them with a proper computer. Still got a knock code after 5 minutes of driving. I understand this thread makes me look kinda dumb but, I'm pretty good at troubleshooting and systematically eliminating potential issues. Usually. Short of pulling my engine and taking it apart, tuning out the knock sensors is my best tool to eliminate 'knock' as the problem.

Well I would hardly say this thread makes you look dumb?? I'm impressed with your ability to "troubleshoot!"

"Tackle" one of these issues at a time. If you've calibrated/replaced the "Knock Sensor" and it's still pulling timing??? That's not right??? Maybe it's the PCM/ECU?? Can you just disconnect the knock sensor and drive it and see what happens???

And under the heading "Stuff I know" on the TPS on GM's, there should be a yellow wire and it should always have 5 volts, if it does not that points to a problem with the PCM/ECM???