Knock sensor or dealer copout?

PapaBear · 07-08-2011, 05:14 PM

So, having my issues with number 8 misfiring at 4000+ RPM. Took to dealer after switching plug, wire, coil, injector, and still same issue.*

Went there today and went for a ride with the tech. He is trying to say that header is hitting frame at WOT and tripping knock sensor to pull timing from #8 only.*

Is this possible? *I know the clearances are tight with the pace setters but can knock sensor pull timing from only one cylinder? *

Or are they tryin to get out of digging deeper into it?

1998ta__1991rs · 07-08-2011, 05:40 PM

knock sensors don't do that

PapaBear · 07-08-2011, 05:46 PM

That's what I thought. Went for a ride with the tech with scanner hooked up and it read 0* knock retard the whole time but he is insisting that's what it is.

PapaBear · 07-08-2011, 06:03 PM

Just got off phone with tech, he's saying his log is showing knock on all cylinders. Once again, blaming it on headers. My Aeroforce shows 150+ misfires on #8 from 4000 through shift and NONE on any other cylinder.*

So pissed.

98nbmz · 07-08-2011, 07:14 PM

Crank sensor maybe? But I dont see that just randomly going out after the mods you did at all. What was the tech using to log the car? Is the mis-fire just a hiccup or constant after 4k? Look for possible drops in voltage.

bambooi · 07-08-2011, 07:34 PM

On my first evo with the wrong downpipe, it hit the transfer case and pulled timing.

chrisheltra · 07-08-2011, 07:39 PM

I have sigs and avatars turned of so excuse me for asking but Im curious what kind of car you are having issues with?

Do you have a tune for your headers?

LXtasy · 07-08-2011, 07:43 PM

Tbss

yota · 07-08-2011, 07:55 PM

http://www.gmfullsize.com/forum/showthread.php?t=90314

possibly?

PapaBear · 07-08-2011, 08:51 PM

So when I talked to him, he says there are only 280 misfires in the history. I unhooked battery the other day, and it has only been driven to "failure" three times since. 2 of them were when he was driving and I was riding shotgun with GM TECH 2 scanner in my lap. It was set on knock retard monitor, and it NEVER showed any knock retard while I had it. He had it recording, and says now that he reviewed the data, it was detecting knock on all cylinders, not just #8.

280 misfires in three 3 second goes at WOT. But if I monitor with aeroforce gauge (can monitor misfires on each cylinder individually), it will hit 150+ on #8 ONLY from 4000RPM through 1-2 shift. So I don't know what to think.

I told him if he felt so strongly about it, to make some clearance....dimple the primary a little bit or dent the fucking framerail, whatever, but that I wasn't going to pick the truck up, do it myself, and then have to bring it back when that wasn't the problem.

I don't know much about knock sensors and retard and all that, but with only 2 sensors, I find it hard to believe that the sensor can sense that only 1 cylinder is knocking b/c of a harmonic "noise/vibration" in the header. Just doesn't make sense. I have heard some valvetrain noise a couple of times, and told them that.

BUT, it seems that he is hell-bent on blaming it on this instead of checking other things first.

Then, he says the "ticking" noise I heard in the valvetrain was water dripping from A/C onto collector....WTF? I'm not a fucking idiot. I told this guy that I wasn't Joe Blow off the street with a TBSS, I have been wrenching on cars all my life, and know what valve train noise is. There was this little plastic hose that comes out of firewall that routes condensation away from exhaust.....well I found the piece of hose in my driveway. Water drips directly on collector, and guess what it sounds like.......water dripping on something hot, UNDER the truck.

I have a feeling that I will be getting a call on Monday saying that they clearanced the header and still have problem. When they tell me it's a valve spring or something like I thought all along, and told them 20 times, I am going to laugh at this guy.

So I told them I wanted Martin, Doug, or Deon, and instead got some young kid named Kelly. We'll see I guess.

bambooi · 07-08-2011, 09:08 PM

That is the bad thing about dealerships. They blame it on mods. If they can't fix it, you need to take it to a tuning shop that knows what they are doing.

PapaBear · 07-08-2011, 09:12 PM

But, of course, if he's right, I will thank him and admit "defeat".

PapaBear · 07-08-2011, 09:12 PM

This is a "mod friendly" dealership and this will be warrantied if it's internal.

schardbody · 07-08-2011, 09:15 PM

its NOT the knock sensor......

tell him to disconnect the knock sensor harness (back of intake manifold), this will set a knock code and retard the shit out of the timing, but it wont cause a misfire.....

tell him he is a fucking moron and pick your truck up, then call GM directly, ask them where to take it for your warranty work because you do not want that service department working on it again.

sounds like the tech just doesnt know his shit, because false knock will not cause a misfire, real knock could possibly, but "if" he is blaming the headers causing false knock then whats up with the misfires? his story doesnt hold up.....

might i ask what dealership this is and what the tech's name was? i know quite a few people in the industry.

1 Slow Z · 07-08-2011, 10:30 PM

Quote:

Originally Posted by schardbody

false knock will not cause a misfire, real knock could possibly, but "if" he is blaming the headers causing false knock then whats up with the misfires?

I'm not too smart on the electronic side of things, but can a PCM differentiate between "false" & "real" knock? How does the PCM know the difference between the two?

BAD BOB · 07-08-2011, 10:39 PM

he is saying that knock in general should not cause a misfire. i dont feel that even if it did cause a misfire that it would single out one cylinder to misfire being that the ignition isnt controlled individually per cyl

PapaBear · 07-08-2011, 09:22 PM

Yep Rick Hendrick chevy in west Ashley. Tech is Kelly as mentioned above.

My uncle worked there for 20+ years, wish he was still there.....

SO, might I ask, what do YOU think it could be? Weak/broken valve spring?

csikx · 07-08-2011, 09:28 PM

Quote:

Originally Posted by PapaBear

Yep Rick Hendrick chevy in west Ashley. Tech is Kelly as mentioned above.

My uncle worked there for 20+ years, wish he was still there.....

SO, might I ask, what do YOU think it could be? Weak/broken valve spring?

So their service department is just as fucking shitty as their sales department, nice! I'd never buy or take anything to those dickfaces at Rick Hendrick.

Hope you get the problem solved man.

98nbmz · 07-09-2011, 10:46 AM

Quote:

Originally Posted by csikx

So their service department is just as fucking shitty as their sales department, nice! I'd never buy or take anything to those dickfaces at Rick Hendrick.

Hope you get the problem solved man.

Hey hey hey... My Uncle Les is a salesman there and he is no dickface sir.

csikx · 07-09-2011, 11:57 AM

Quote:

Originally Posted by 98nbmz

Hey hey hey... My Uncle Les is a salesman there and he is no dickface sir.

Diamond in the rough

.

07-08-2011, 05:14 PM	#1
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	Knock sensor or dealer copout? So, having my issues with number 8 misfiring at 4000+ RPM. Took to dealer after switching plug, wire, coil, injector, and still same issue.* Went there today and went for a ride with the tech. He is trying to say that header is hitting frame at WOT and tripping knock sensor to pull timing from #8 only.* Is this possible? I know the clearances are tight with the pace setters but can knock sensor pull timing from only one cylinder? Or are they tryin to get out of digging deeper into it?

07-08-2011, 05:40 PM	#2
1998ta__1991rs Senior Member Join Date: Jun 2008 Location: West Ash Posts: 4,283	knock sensors don't do that __________________ Funny

07-08-2011, 07:14 PM	#5
98nbmz Senior Member Join Date: Oct 2009 Location: Ridgeville Posts: 1,167	Crank sensor maybe? But I dont see that just randomly going out after the mods you did at all. What was the tech using to log the car? Is the mis-fire just a hiccup or constant after 4k? Look for possible drops in voltage. __________________

07-08-2011, 07:39 PM	#7
chrisheltra Neo is Jesus Join Date: Jan 2007 Posts: 13,265	I have sigs and avatars turned of so excuse me for asking but Im curious what kind of car you are having issues with? Do you have a tune for your headers? __________________ Gap A Hoe Racing

07-08-2011, 07:55 PM	#9
yota Senior Member Join Date: Jun 2011 Location: Va Posts: 1,049	http://www.gmfullsize.com/forum/showthread.php?t=90314 possibly? __________________ 1999 Trans Am 2007.5 Dodge Mega Cab Cummins

07-08-2011, 05:46 PM	#3
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	That's what I thought. Went for a ride with the tech with scanner hooked up and it read 0* knock retard the whole time but he is insisting that's what it is.

07-08-2011, 06:03 PM	#4
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	Just got off phone with tech, he's saying his log is showing knock on all cylinders. Once again, blaming it on headers. My Aeroforce shows 150+ misfires on #8 from 4000 through shift and NONE on any other cylinder.* So pissed.

07-08-2011, 07:34 PM	#6
bambooi Senior Member Join Date: Apr 2009 Posts: 1,324	On my first evo with the wrong downpipe, it hit the transfer case and pulled timing.

07-08-2011, 07:43 PM	#8
LXtasy Senior Member Join Date: Dec 2006 Location: Summerville, SC Posts: 9,564	Tbss __________________

07-08-2011, 08:51 PM	#10
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	So when I talked to him, he says there are only 280 misfires in the history. I unhooked battery the other day, and it has only been driven to "failure" three times since. 2 of them were when he was driving and I was riding shotgun with GM TECH 2 scanner in my lap. It was set on knock retard monitor, and it NEVER showed any knock retard while I had it. He had it recording, and says now that he reviewed the data, it was detecting knock on all cylinders, not just #8. 280 misfires in three 3 second goes at WOT. But if I monitor with aeroforce gauge (can monitor misfires on each cylinder individually), it will hit 150+ on #8 ONLY from 4000RPM through 1-2 shift. So I don't know what to think. I told him if he felt so strongly about it, to make some clearance....dimple the primary a little bit or dent the fucking framerail, whatever, but that I wasn't going to pick the truck up, do it myself, and then have to bring it back when that wasn't the problem. I don't know much about knock sensors and retard and all that, but with only 2 sensors, I find it hard to believe that the sensor can sense that only 1 cylinder is knocking b/c of a harmonic "noise/vibration" in the header. Just doesn't make sense. I have heard some valvetrain noise a couple of times, and told them that. BUT, it seems that he is hell-bent on blaming it on this instead of checking other things first. Then, he says the "ticking" noise I heard in the valvetrain was water dripping from A/C onto collector....WTF? I'm not a fucking idiot. I told this guy that I wasn't Joe Blow off the street with a TBSS, I have been wrenching on cars all my life, and know what valve train noise is. There was this little plastic hose that comes out of firewall that routes condensation away from exhaust.....well I found the piece of hose in my driveway. Water drips directly on collector, and guess what it sounds like.......water dripping on something hot, UNDER the truck. I have a feeling that I will be getting a call on Monday saying that they clearanced the header and still have problem. When they tell me it's a valve spring or something like I thought all along, and told them 20 times, I am going to laugh at this guy. So I told them I wanted Martin, Doug, or Deon, and instead got some young kid named Kelly. We'll see I guess.

07-08-2011, 09:08 PM	#11
bambooi Senior Member Join Date: Apr 2009 Posts: 1,324	That is the bad thing about dealerships. They blame it on mods. If they can't fix it, you need to take it to a tuning shop that knows what they are doing.

07-08-2011, 09:12 PM	#12
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	But, of course, if he's right, I will thank him and admit "defeat".

07-08-2011, 09:15 PM	#14
schardbody Senior Member Join Date: Sep 2008 Posts: 1,158	its NOT the knock sensor...... tell him to disconnect the knock sensor harness (back of intake manifold), this will set a knock code and retard the shit out of the timing, but it wont cause a misfire..... tell him he is a fucking moron and pick your truck up, then call GM directly, ask them where to take it for your warranty work because you do not want that service department working on it again. sounds like the tech just doesnt know his shit, because false knock will not cause a misfire, real knock could possibly, but "if" he is blaming the headers causing false knock then whats up with the misfires? his story doesnt hold up..... might i ask what dealership this is and what the tech's name was? i know quite a few people in the industry.

07-08-2011, 10:39 PM	#16
BAD BOB Senior Member Join Date: Mar 2008 Location: SUMMERVILLE Posts: 3,681	he is saying that knock in general should not cause a misfire. i dont feel that even if it did cause a misfire that it would single out one cylinder to misfire being that the ignition isnt controlled individually per cyl __________________ IM BAD BOB

07-08-2011, 09:22 PM	#17
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	Yep Rick Hendrick chevy in west Ashley. Tech is Kelly as mentioned above. My uncle worked there for 20+ years, wish he was still there..... SO, might I ask, what do YOU think it could be? Weak/broken valve spring?