Mystery knock hunting.

[Epppy]

I have the same issues. I Checked the maf. Valves have been adjusted. Every bolt tightened. New timing belt and gears. I can get up to -30 knock on stage 1, I'm running stage 0 and get up to -10 knock. All under low load.

My mechanics have all said not to worry and the only way they think it will get fixed is a custom tune.

[brcreswell1]

Yea man, it is so unbelievably frustrating. I will keep you all posted. The search will continue until I either find the problem or sell the car! I just find it hard to believe that it could be false knock if it varies between tunes.

 

As far as everyone has told me, the Cobb tunes and the stock tune handle knock the same. So if the knock was something rattling, it should stay the same.

 

2005 LGT MT stage 1

[brcreswell1]

So folks I've done tons to this car and figured I owed an update. I discovered that my right front ocv valve wasnt functioning properly, and I replaced it. I was soooo sure this was going to be my knock problem.... But I was let down. Oh well, it needed to be done anyway.

 

However, it cleaned up my knock on the stock tune immensely, I get a max of -2 feedback occasionally and no learned.

 

Ive done a downpipe and several other things and so when I run the Cobb stage 2 map, I get tons of knock, feedback knock goes straight to -12 on mild accel, and learn quickly jumps up. This all occurs between 0.20 and 1.20 load. I have yet to see an even above that load level. But 1.20 is not exactly low load anymore. I have accesstuner and the way the two maps handle knock is identical from what I can see. So at this point I think it really must be real knock.

 

2005 LGT MT stage 1

[Infosecdad]

Sounds like you really need a custom tune, the Cobb stage 2 map isn't a very good catch all map.

[brcreswell1]

Alright, just want to make sure I'm nit gonna blow up from another mechanical issue before I shell out the money for a tune.

 

2005 LGT MT stage 1

[mwiener2]

What UpPipe do you have?

[brcreswell1]

Invidia, it did this on the stock one as well though. It occasionally will still still pull timing on the stock map as well, it seems to have returned to normal, around -6 occasionally. Still not as bad as the stg 2 map

 

2005 LGT MT stage 1

[brcreswell1]

Little extra info, my af learning A usually hovers around 10-13+, while all my other learning values are normal. I can figure out what the issue is. I've boost/vacuum leak tested several times and found nothing.

 

2005 LGT MT stage 1

[Mr-C]

Damn....how many are we going through this wild goose chase !!???

[Mr-C]

Check for loose exhaust heatshields or anything that would rattle near the knock sensor. Also verify the correct orientation of the knock sensor.

 

Can someone elaborate on this or provide a pic.....I recently changed mine and wasn't aware there was a specific orientation

 

 

Thanks,

[rhino6303]

Can someone elaborate on this or provide a pic.....I recently changed mine and wasn't aware there was a specific orientation

 

 

Thanks,

Here is a picture from the FSM. It is on page FU(H4DOTC)-25. Note that the top of the picture is the front of the car.

[xt2005bonbon]

Very VERY interesting. I did not even know that. I will promptly check mine on the car that loves to knock at low load and report -6 deg timing correction.

[Mr-C]

Here is a picture from the FSM. It is on page FU(H4DOTC)-25. Note that the top of the picture is the front of the car.

 

 

Thank you....much appreciated!

[mwiener2]

I think the orientation has more to do with the wire not getting bent or folded. The knock sensor is a microphone and is not directional.

[brcreswell1]

Yea I've double checked my orientation and torque and everything. I'm almost positive at this point that my knock is real, changing tunes makes a huge difference, while adjusting timing has no effect, so at this point I think it has to be one of a few things, fueling, avcs issues, burnt out valve or other internal issue, or a vacuum leak I can't find. I've essentially replaced all sensors except the rear o2, I'm at a loss. I've been sending various logs to Cobb to have them look it over. Will continue to update on any progress I make.

 

The only difference I see in the ots map vs the stock map in these load regions is the avcs advance tables, so I'm feeling like this may be me issue (I have access tuner) the timing changes are not significant, a max of 0.70 increase from what I can see.

 

2005 LGT MT stage 1

[ehsnils]

Have you checked all pulleys on the engine including the alternator and the AC compressor?

 

 

For example the alternator bearings can become noisy a long time before the alternator dies.

 

 

Also the power steering could cause noise that could be detected as knock.

[brcreswell1]

Yes the pulleys are very quiet, my power steering does have a leak but I keep it topped off so it doesn't squeal.

 

2005 LGT MT stage 1

[ehsnils]

Yes the pulleys are very quiet, my power steering does have a leak but I keep it topped off so it doesn't squeal.

 

 

And is that on all rpms? Just because it's silent while idling doesn't mean that it's not causing problems at higher rpms. The experience I have is that the early stage of a bearing failing still can be silent until a certain rpm.

[brcreswell1]

I'd need to setup a go pro or something, there's nothing that I can hear while driving/revving but my exhaust is pretty loud so.

 

2005 LGT MT stage 1

[brcreswell1]

Figured it was time for an update. Haven't solved my problem but.... I now know without a reasonable doubt that my knock is real. After weeks of talking with Cobb and sending them logs, they sent me a map with extremely conservative parameters, and my knock magnitude was cut in half. The car has like no power with this tune but I've been driving it with this map as it is safer. I went a step colder on plugs but still have the same issues. At this point I feel I may have a valve issue or something I really have no idea.

 

2005 LGT MT stage 1