CEL code #31

[94'TSI'AWD]

<Turbo> Knock Sensor, Is the only code my car is throwing, i am replacing the knock sensor but my question is, Is there any way to get to the knock sensor on a 4G63T without having to remove the intake manifold?

And

Still runs like crapola and wont idle.

Still Blowing black smoke

Still getting 12mpg city

 

[TFFC]

Yes you can get the knock sensor out without taking off the manifold. You can go from the top or I the bottom, I believe bottom is easier but you need to have the front of the car jacked up. It prob runs like crap because your running crazy rich, which is why you have black smoke. You need a logger so you can look at your fuel trims.

 

[snakeyes711]

I unhooked my battery, and used an adjustable wrench.

 

[steve]

Still runs like crapola and wont idle.

Still Blowing black smoke

Still getting 12mpg city

The knock sensor is going to make it run like a dog but it's not going to do all this.

Have you checked your ECU?
Do you have a logger? (asking since there are other ways you might read the code)

 

[95talongirl]

Sounds like the faulty knock sensor is "sensing" too much knock and telling the computer to make it run super rich; hence the black smoke. So yeah, I'd get a new one on there... see what happens. Then get something to log with.

 

[snakeyes711]

Um, knock sensor doesn't do that, it does retard ignition timing advance. It wouldn't make MPG go down that bad? Maybe you should check your o2 sensor also? Are you absolutely sure there's not a massive boost leak? Check to see if the knock sensor is even plugged in. Check to see if its tight, Check the connection, Visually look at it to see if the black stuff surrounding it has leaked out, or is leaking out. Then reset the battery. I'm guessing you don't have a logger?

 

[GooeyGus]

A bad knock sensor can kill fuel economy because your timing advance will be gone. It will be slow as hell and get bad mileage, but it shouldn't be blowing black smoke because even though you have no timing advance, the a/f ratio should still be correct.

Assuming your ECU is working correctly, I would say there is a vac/boost leak somewhere.

Also, if your A/C isn't in the way, it is super easy to reach in through the drivers side with a crescent wrench and change the knock sensor. Took me about 5 minutes.

 

[snakeyes711]

Right, so check the o2.
look for a massive boost leak.
Change the knock sensor.
check ecu.

If it still acts up after the first three, I'd suspect the ECU.

 

[95talongirl]

ok, i stand corrected.. I guess what i was trying to say is its running rich in reality, but the computer thinks its correct; by getting the wrong signals.

snakeyes has a good list going there of things to check.

 

[snakeyes711]

ok, i stand corrected.. I guess what i was trying to say is its running rich in reality, but the computer thinks its correct; by getting the wrong signals.

snakeyes has a good list going there of things to check.

No problem, If the o2 isn't working thats another story. Also if there is a massive boost leak that'll happen too....You know, thinking about it are the injectors OE?

 

[94'TSI'AWD]

No problem, If the o2 isn't working thats another story. Also if there is a massive boost leak that'll happen too....You know, thinking about it are the injectors OE?

yes the injectors are factory size, i actually had the entire fuel rail, injectors, and seals redone about 3 months ago. I am not sure exactly how to find a boost leek, What i plan on doing is removing all the unneeded vacuum lines and try to eliminate emissions equipment that is not needed....Oregon has lowest emissions.

So what all can be removed and is there a website that can show me what and how to remove unneeded emissions equipment that can cause more issues than i want right now?

 

[snakeyes711]

yes the injectors are factory size, i actually had the entire fuel rail, injectors, and seals redone about 3 months ago. I am not sure exactly how to find a boost leek, What i plan on doing is removing all the unneeded vacuum lines and try to eliminate emissions equipment that is not needed....Oregon has lowest emissions.

So what all can be removed and is there a website that can show me what and how to remove unneeded emissions equipment that can cause more issues than i want right now?

I got a EGR blockoff plate from a 1.8 from the junk yard, and sealed that off. I just put the EGR back on with the plate in between with some high temp RTV.

First off I'd make up a boost tester, and attach it to the turbo inlet, and test for pressure through the inter cooler up to the throttle body. Then attach it straight to the throttle body, and test it. My point is test it in sections, so you aren't over whelmed with leaks.

Also when you test at the throttle body you have to turn the engine to about 30* after TDC. What I do is get TDC then rotate the engine till the notches on the cams that meet together, are then pointing out thats about 30*.

http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/169435-boost-leak-test-how-boostpro-net-tester.html

 

[TFFC]

Removing the emission stuff is not going to solve your problem. I don't understand why people do it to begin with, their is no performance gain, and it just takes aways mpg. Yeah your engine bay will have less vaccum lines, but their is what, 4 of them? Check, test, and fix your knock sensor and go from their. Don't (FIX) what isn't broken