Engine Knock!
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Member
Joined: Apr 2008
Posts: 32
From: Erie, PA
Engine Knock!
Ever since I installed a 3" ATP cat-delete pipe, I've been getting knock from about 1300-3800 RPM, but only under light/part throttle (such as driving to conserve gas). No knock when at wide open throttle such as doing 2nd or 3rd gear pulls etc.
2001 A4 1.8TQM with Borla cat-back and everything else is basically stock. Data logging with VAG-COM. I want to get a chip etc, but at this point I don't see how advancing timing is a good thing!
Any ideas or similar situations? Any help please?
-Thanks
2001 A4 1.8TQM with Borla cat-back and everything else is basically stock. Data logging with VAG-COM. I want to get a chip etc, but at this point I don't see how advancing timing is a good thing!
Any ideas or similar situations? Any help please?
-Thanks
Thread Starter
|
Member
Joined: Apr 2008
Posts: 32
From: Erie, PA
RE: Engine Knock!
No codes. And it's not an audible knock... I can't hear it when it's happening.
Here is a VC Scope of a couple normal stops and gos on the way out of my neighborhood.
[IMG]local://upfiles/52517/2BAF561027FF404EA0113EBB1561392F.jpg[/IMG]
Here is a VC Scope of a couple normal stops and gos on the way out of my neighborhood.
[IMG]local://upfiles/52517/2BAF561027FF404EA0113EBB1561392F.jpg[/IMG]
3rd Gear
Joined: Oct 2007
Posts: 2,158
From: CT
RE: Engine Knock!
only thing i could think of that has to do with the test pipe would be an O2 sensor. you normaly have to add a spacer to the after-cat O2 sensor so it doesnt throw a code, maybe if you had a bad 02 sensor to begin with its doing something weird to the fuel trims.
this would make sense because at WOT the ECU is ignoring the O2 sensor readings of too lean/too rich and running off preset software that tells it how the fuel should be injected.
in other words, over 60-80% throttle its running off what the software says to do, under 60-80% throttle its looking at sensor readings and adjusting fuel/timing/etc to what the computer thinks is optimum. if one of its sensors is not working it might be misjudging whats going on in the engine.
this would make sense because at WOT the ECU is ignoring the O2 sensor readings of too lean/too rich and running off preset software that tells it how the fuel should be injected.
in other words, over 60-80% throttle its running off what the software says to do, under 60-80% throttle its looking at sensor readings and adjusting fuel/timing/etc to what the computer thinks is optimum. if one of its sensors is not working it might be misjudging whats going on in the engine.
SoCal Crew Member
Joined: May 2008
Posts: 1,215
From: Covina, CA
RE: Engine Knock!
Does this problem exist only when you first start your car or is it a constant nag? I had a similar issue, but I was just a little low on oil. My car would knock a bit when I first started it up, but after the oil pressure built up a bit, the knocking went away. I topped off my oil shortly after I noticed this and viola! No more knocking. Could be a VERY easy fix. 
Thread Starter
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Member
Joined: Apr 2008
Posts: 32
From: Erie, PA
RE: Engine Knock!
ORIGINAL: ghost6303
only thing i could think of that has to do with the test pipe would be an O2 sensor. you normaly have to add a spacer to the after-cat O2 sensor so it doesnt throw a code, maybe if you had a bad 02 sensor to begin with its doing something weird to the fuel trims.
this would make sense because at WOT the ECU is ignoring the O2 sensor readings of too lean/too rich and running off preset software that tells it how the fuel should be injected.
in other words, over 60-80% throttle its running off what the software says to do, under 60-80% throttle its looking at sensor readings and adjusting fuel/timing/etc to what the computer thinks is optimum. if one of its sensors is not working it might be misjudging whats going on in the engine.
only thing i could think of that has to do with the test pipe would be an O2 sensor. you normaly have to add a spacer to the after-cat O2 sensor so it doesnt throw a code, maybe if you had a bad 02 sensor to begin with its doing something weird to the fuel trims.
this would make sense because at WOT the ECU is ignoring the O2 sensor readings of too lean/too rich and running off preset software that tells it how the fuel should be injected.
in other words, over 60-80% throttle its running off what the software says to do, under 60-80% throttle its looking at sensor readings and adjusting fuel/timing/etc to what the computer thinks is optimum. if one of its sensors is not working it might be misjudging whats going on in the engine.
Love the booB5 - I have oil in my car, it's not that kind of knock. But thanks for the input.
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