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Those codes are going to be set when the ECM fails to detect a signal from the knock sensor in the expected voltage range.

The issue is either in the knock sensor, circuit, or the ECM.

I'll post the service manual diagnostic procedure in a sec.
 

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Discussion Starter · #23 ·
Thanks, NotHubert. On a whim, I ordered an AC Delco knock sensor ($10) yesterday and it arrived this afternoon. I removed the old one and installed the new one. Not a hint of corrosion on the factory one. (Actually I was hoping to find a corroded mating surface, since that's the only part I couldn't inspect)

I only test drove it a short while afterwards to check my work - I've had a pretty full day with upholstery projects on my truck and I'm beat. I'll drive the GTO over the next two days, and if the problem shows up again, I'll be using your shop manual steps to work through it.
 

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Thanks, NotHubert. On a whim, I ordered an AC Delco knock sensor ($10) yesterday and it arrived this afternoon. I removed the old one and installed the new one. Not a hint of corrosion on the factory one. (Actually I was hoping to find a corroded mating surface, since that's the only part I couldn't inspect)

I only test drove it a short while afterwards to check my work - I've had a pretty full day with upholstery projects on my truck and I'm beat. I'll drive the GTO over the next two days, and if the problem shows up again, I'll be using your shop manual steps to work through it.
Has it come back?
 

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Discussion Starter · #25 ·
Has it come back?
It's been raining here almost daily, so I've been driving my truck; I've only taken the GTO on two short errands of about 7-8 miles - and I'm not convinced of anything yet, especially considering it took 30-40 total miles before it would trigger the CEL. I badly want to put this to bed, but between weather and work, I cant say one way or the other.
 

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Discussion Starter · #26 ·
Drove it into Dallas today with the new Bank 1 sensor - it tripped the code when I was close to my destination (about 25 miles). I cleared it and when I got close to him, it tripped again. Frustrating.
 

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Drove it into Dallas today with the new Bank 1 sensor - it tripped the code when I was close to my destination (about 25 miles). I cleared it and when I got close to him, it tripped again. Frustrating.
any other info about what the car was doing or what was happening to the car when it tripped?

also looking at an e40 tune file, and wondering if changing any of the settings in engine/spark/knock sensors did anything. maybe he tried to "desensitize" them by changing the values, and now this is causing issues. not something i have ever messed with, personally, as i would prefer the sensors just do their job as intended.
 

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Discussion Starter · #29 · (Edited)
any other info about what the car was doing or what was happening to the car when it tripped?

also looking at an e40 tune file, and wondering if changing any of the settings in engine/spark/knock sensors did anything. maybe he tried to "desensitize" them by changing the values, and now this is causing issues. not something i have ever messed with, personally, as i would prefer the sensors just do their job as intended.
I also believe you're on the right track with the above. I have 5-6 websites open that talk about the issue, because if I can't learn where specifically to point him & suggest to him "what to change back", then I'm afraid he'll just shrug and not know the cause, either.

One example : Link

I also get the P0327 and a Pending Fault P0332. Some value must be making Bank 1 trip the light, and almost make the Bank 2 do it too.

Edit: The answer your question, I was just cruising home on the Tollway, about 75mph; Not racing, not WOT, nothing unusual. It doesn't seem to be temp or speed related that I've noticed.
 

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still suggest buying the mpvi2 and looking over the tune yourself. itd be a 5 min fix if that was the case and if he just shrugs it off id find a new tuner
or just learn to do it yourself.

one thing i have learned with hptuners, just because there's a table or a value for something, doesn't mean it's a good idea to change it, or change it much if you do...
 

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or just learn to do it yourself.

one thing i have learned with hptuners, just because there's a table or a value for something, doesn't mean it's a good idea to change it, or change it much if you do...
Agree. I know ive been trying and am grateful for the help i get. Im at the point where i can start playing with spark but its so hot out i dont want to be trying to tune it in this weather with a heatsoaked box.
 

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Discussion Starter · #35 ·
UPDATE: My tuner followed up with me by email, and I shared with him some of the ideas I had from tons of reading and researching this issue. He said he's make it right by me, no matter what.

Because I mentioned it, he added that he did not touch the knock sensor gain or sensitivity settings when he originally did the tune. He had some time yesterday, so I cleared the CEL drove toward his shop and after only 12 miles into my trip there, the code popped up again. I arrived at 1pm, and he plugged in his laptop and downloaded my tune (that he had built) and compared it to my stock tune.

He said there was a small variance in the Knock Sensor 'floor setting' that it uses a parameter to understand what's the normal range it should be looking to stay between. I asked him if this value was in voltage, and he said no, that it was an arbitrary value (some of my research said that if it dropped below 400mv, it would trip the CEL, but it doesn't seem to be as clear cut as that). I couldn't see exactly what menu he was in, nor did I ask. He changed that specific setting back to the stock value, and uploaded the new tune.

He had another customer appointment and asked if I would please go drive it and report back. Over the next two hours, I drove it through neighborhoods where it got plenty heat soaked (IAT at 140*F), and then jumped on the highway and drove it 25 miles toward Dallas. I stopped, picked up a cold drink, made a couple of more stops, walked around, etc - essentially gave it every condition I could think of to cause the code to return.

One other thing I noticed in driving is that, without even trying, I easily broke the tires loose taking off from red lights and just doing city driving. This seemed surprising because it was hot outside - 96*F - and heat soaked and it left me wondering if this bad setting had it pulling timing even before it tripped the CEL. It ran really well on a hot day when my car has always, always felt 'slow' under these conditions.

In the end, I then drove back to his shop to give him feedback. A total of 58 miles travelled and the code seems to be gone due to the change he made. Shook his hand as he pulled in a Dodge Viper to tune and he seemed also glad that it problem was fixed. For such a small little light on the dash, it had me frustrated and I felt the stress just melt away after this mini road trip to test it.

I just wanted to wrap this story up so you'd know...Thanks for all of the input and ideas, guys!
 

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he added that he did not touch the knock sensor gain or sensitivity settings when he originally did the tune. He had some time yesterday, so I cleared the CEL drove toward his shop and after only 12 miles into my trip there, the code popped up again. I arrived at 1pm, and he plugged in his laptop and downloaded my tune (that he had built) and compared it to my stock tune.

He said there was a small variance in the Knock Sensor 'floor setting' that it uses a parameter to understand what's the normal range
it should be looking to stay between. I asked him if this value was in voltage, and he said no, that it was an arbitrary value (some of my research said that if it dropped below 400mv, it would trip the CEL, but it doesn't seem to be as clear cut as that). I couldn't see exactly what menu he was in, nor did I ask. He changed that specific setting back to the stock value, and uploaded the new tune.
Go buy your own mpvi2 and you wont be left in the dark. It doesnt just change randomly.

It is 400mv
yep. he changed it to begin with. i would not go back to that tuner.
 

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Discussion Starter · #38 ·
Go buy your own mpvi2 and you wont be left in the dark. It doesnt just change randomly.

It is 400mv
Thanks for the screenshot.
I googled the mpvi2 when you mentioned a while back - isn't it roughly $299? That's a little more change than I have to tinker with, esp after paying for the tune to start with. Good idea, but I dont trust myself not to get daring and melt a piston or something.
 
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