Huge hesitation, mechanically inclined. Please help

[Brian Wilson]

Anything worth a shot. I wish I had gotten the v2 instead of the autocal. Being able to change stuff myself would be so much faster. I would have still left the tuning to them. They have a great rep for a reason I'm sure.

 

[iamdub]

I don't think you look dumb at all. You're plenty methodical and show adequate experience in your troubleshooting. I think you're just dealing with one of those hard-to-nail issues. It being intermittent only makes it more difficult. Any freeze frames of this knock sensor code(s)? The sensors themselves could be fine but something is still telling the PCM to pull timing. Or maybe there's an intermittent fault in the wiring between the knock sensor(s) and the PCM. IAT is another sensor that affects timing. Maybe the PCM is (falsely) detecting wheel spin and is pulling timing because of the Torque Management tables? Perhaps a faulty wheel speed sensor or a fault in the ABS system (which you may have based on your previous findings, but lets not dive down that wormhole just yet) is telling the PCM that a wheel or wheels is losing traction, and the PCM is pulling timing to reduce power to get the truck back under control, but there's actually no lost traction in the first place. The PCM doesn't "see" a problem, it's just doing what it's programmed to do in response to what it's told by sensors and modules. But, you have these knock sensor codes being thrown that may not even be related, so I'd start by reviewing the freeze frames for this/these code(s).

 

[Chip18]

I don't think you look dumb at all. You're plenty methodical and show adequate experience in your troubleshooting. I think you're just dealing with one of those hard-to-nail issues. It being intermittent only makes it more difficult. Any freeze frames of this knock sensor code(s)? The sensors themselves could be fine but something is still telling the PCM to pull timing. Or maybe there's an intermittent fault in the wiring between the knock sensor(s) and the PCM. IAT is another sensor that affects timing. Maybe the PCM is (falsely) detecting wheel spin and is pulling timing because of the Torque Management tables? Perhaps a faulty wheel speed sensor or a fault in the ABS system (which you may have based on your previous findings, but lets not dive down that wormhole just yet) is telling the PCM that a wheel or wheels is losing traction, and the PCM is pulling timing to reduce power to get the truck back under control, but there's actually no lost traction in the first place. The PCM doesn't "see" a problem, it's just doing what it's programmed to do in response to what it's told by sensors and modules. But, you have these knock sensor codes being thrown that may not even be related, so I'd start by reviewing the freeze frames for this/these code(s).

Absolutely ... "no disagreement here" frankly ... I think the "TC" on these things is kinda slow. If your quick with the steering wheel and the throttle ... you can beat it!

Making a hard left ... I thought for a sec ... the brakes were being applying?? But I got the wheels pointed straight as I applied the throttle and the thing shot forward like being fired from a cannon ... pretty cool!

But back on pointe ... look at the wheel sensor harness for both the front front wheels. On my 951 ... it had "ABS" issues ... "Sorry that system is not available??" That is a real issue for as I tend to do a lot of late threshold braking! But whatever ... while working on other issues the wires for the ABS sensors came into focus?? What I noticed was that all the stuff that should have been the same on both sides ... was not???

At any rate if the Knock Sensor is new then it should be fine??? But I think you should be able to check the input connector that goes to the "Knock Sensor??"

That's not "addressing the "TC" issue but it maybe a start?? If the brakes are being applied ... then the "TC" may say "hey ... we have an issue here???"

 

[Brian Wilson]

Brakes still seem to be ok since pressure bleeding correctly. Cost me almost a gallon of fluid but I'm happy if it's really fixed. I may never go back to vacuum bleeding. Still retarding timing. I'm going to borrow the tech 2 this coming weekend for some more fun.

Also, still haven't heard back from blackbear on my tune. But I got a set of DNA long tube headers that came off an escalade. Don't know anything about them but they have 1 7/8 primaries and have a 3/8 flange. All stainless steel and look tig welded inside and out. 150$ total. Might just wait on that tune until I installed them.

 

[Brian Wilson]

Also, isn't the IAT built into MAF sensor on my car? I believe it is and I have already eliminated that possibility if I'm correct.

 

[retiredsparky]

Can you not use the Snapon tool to monitor temp sensors value? Coolant and intake air are both tied to PCM are they not?

 

[Brian Wilson]

Yes you can. And they looked normal. And since that data comes from the computer it would eliminate a bad connection between the sensor and ecu itself

 

[retiredsparky]

Years ago I fixed a 327 chevy that had been overheated. The engine would accelerate slowly, even in neutral. I pulled the pistons, measured them cold, then heated a couple of pistons in an oven (mom asked "what the .... is that smell?"). After measuring, the pistons were going egg-shaped when heated.

My point is not that this is your problem, but that sometimes there are bizarre causes for vehicles misbehaving.

 

[Brian Wilson]

FINALLY SOLVED!!!!

THANK EVERYONE FOR STICKING WITH ME THIS THREAD AND OFFERING KNOWLEDGE AND INSIGHT!

I sent my driving logs to Justin at blackbear for my tune. His first response was 'It REALLY looks like a bad knock sensor.try changing them both'.

I had just changed them before sending him my data logs but, at 10$ each I figured wtf. Turns out that either A)I tightened them too much and broke 1 (30ft lbs is supposed to be used)
Or more likely B)I bought at least 1 bad sensor from autozone. Wouldn't be the first time duralast electronics let me down.
I changed the one on drivers side (bank 1) and decided to test drive before even calibrating it.
All my little ponys are back with a vengeance! I havent even got my tune and i am a blackbear fan for life. So happy to have this fixed. Even if I feel like an idiot for all the work I did to get here. I hope this might help someone else in the future.

And I hope this thread stays dead forever.

 

[Rocket Man]

Somewhat similar to my recent problem. I was having random "stumbling" issues ( for lack of a better description) at idle, for a couple months. Every once in awhile, at an idle, my engine would drop in RPM's , like the key was turned off for a fraction of a second. It would usually almost die and actually did twice. No codes. I tried a few things with no luck. Then I emailed BB and asked if I could do a data log with my Autocal and have them look for the cause. They said sure. Then when I was getting ready to log, I remembered when I was logging before my tune and when BB looked at my data, Justin had mentioned my MAF was all over the place. It was new so I thought something was wrong with the data. Anyway, he managed to get a tune done. But I started thinking...maybe my new MAF was bad. So I bought another, an AC Delco. Problem solved. So yes I'm a BB fan also. That's why I mentioned earlier that you should ask them for their opinion. Glad you figured it out!