Yet another problem.. Knock sensor

**flybird** · 12-30-2011, 03:22 PM

Today I went to go gef my texas inspection done. It failed bc of 2 codes(which I thought I erased) a knock sensor bank 2, and IAT low input.

1st off, I know the IAT code is bc if my performance moduel set on efficiency.

2nd.. Where is this knock sensor? Considering it says bank 2, are there more than 1 sensor? Do you have to drop the engine to get to it? Scale 1-10, 10 being the hardest, how hard is this job todo your self?

**Knight** · 12-30-2011, 05:57 PM

Knock sensors are located under the intake manifold. I'm not as familiar with the v6 setup, so hopefully Smittro will check in. It's not too complicated, depending on mechanical ability. For me, I'd say a 1-3. If you don't turn wrenches much, 6 to 8.

**flybird** · 12-30-2011, 06:41 PM

So if you say its under the intake mani, does this mean I have to pull it off and buy new gaskets?

**Smittro** · 12-30-2011, 10:58 PM

The knock sensor is located in the side of the block on most older GM v6's.

Can't recall off hand which side but it will be a round about 1-1/2 to 2 inches in diameter and have one wire coming out of it.

It's really only serviceable from under the car/engine.. and yes you have 2, one on each side.

**Smittro** · 12-30-2011, 11:04 PM

Here: Bank 2

**Smittro** · 12-30-2011, 11:05 PM

The picture puts (bank 2) it on the left side of the engine, behind the AC compressor..

You'll have to move the campressor (carefully) out of the way to get @ it.

The motor mount and K-member will be behind the area of the sensor.

Tight sqweeze.. If you have the tools not hard.

**Knight** · 12-31-2011, 04:39 AM

Wow, that's completely different from where I was thinking. Sorry about that. Looks a little tight, but easier than the v8 location.

**Knight** · 12-31-2011, 05:03 AM

Does the sensor just thread into a bung or well on the side of the block? In other words, it's a dry swap - not tapped into an oik or coolant channel? I need to bone up on my older v6 stuff.

**Smittro** · 12-31-2011, 06:34 AM

Originally Posted by Knight

Does the sensor just thread into a bung or well on the side of the block? In other words, it's a dry swap - not tapped into an oik or coolant channel? I need to bone up on my older v6 stuff.

They both thread right into the block facing the center bores in an open galley. Oil can come out of the hole but its not pressurized.

Very simplistic tech, that's why they are not known to go bad, as it's only looking for a viration or frequency to detemine if knock is present.

Many times minor knock is present, but the sensor does'nt even pick it up.

The sensor itself has been unchanged in many GM V6's for about 30 years.

Earlier V6's had only one sensor, late 1996 the Series-II 3800 recieved 2 knock sensors across the board whether in and FWD or RWD configuration..

**flybird** · 12-31-2011, 06:58 AM

Is the knock sensor a part you can just twist and turn or is it nutted in the block?

**flybird** · 12-31-2011, 07:08 AM

Also, move the compressor out of the way?? Like pull it out and disconnect everthing? Shit, seems a bit too much for my knowledge.

**flybird** · 12-31-2011, 07:25 AM

Take that back you dnt have to take out the compressor... Sorry. I see it though. Theres a black braket blocking it though, can I remove it?

**Knight** · 12-31-2011, 07:37 AM

Originally Posted by Smittro

They both thread right into the block facing the center bores in an open galley. Oil can come out of the hole but its not pressurized.

Very simplistic tech, that's why they are not known to go bad, as it's only looking for a viration or frequency to detemine if knock is present.

Many times minor knock is present, but the sensor does'nt even pick it up.

The sensor itself has been unchanged in many GM V6's for about 30 years.

Earlier V6's had only one sensor, late 1996 the Series-II 3800 recieved 2 knock sensors across the board whether in and FWD or RWD configuration..

Thanks Steven. Good info.

**Smittro** · 12-31-2011, 10:41 AM

Originally Posted by flybird

Is the knock sensor a part you can just twist and turn or is it nutted in the block?

Originally Posted by flybird

Take that back you dnt have to take out the compressor... Sorry. I see it though. Theres a black braket blocking it though, can I remove it?

Going on memory here, I believe that black bracket is part of the AC compressor mount..iirc

Some knock sensors have a hex nut shape stamped in them in which you can put a socket on.

Some have it under the sensor body between the block and sensor where it's hard to get @.

If you have the new one in hand, then you can prolly use a set of locking pliers to unscrew the junk one, since it's just threaded into the block.

3800's love to leak oil so it's likely well greased and should be relatively easy to turn.

Problem you're gonna have is room to work. Be sure to get it tight or motor oil will weep from the threads.

Originally Posted by Knight

Thanks Steven. Good info.

No prob bro..

**flybird** · 12-31-2011, 02:25 PM

Job is done. I got the new knock sensor on. Only thing is though, oil didnt come out of the knock sensor hole, antifreeze/water did. ATON did. So I put anti freeze back in the car and turned it on. I noticed it started getting hot QUICK. About 230 degrees farh until I killed it.. Im thinking theres gaps thru the engine where it needs water so im going to let it cool down and see if she needs more anti freeze.

If water was NOT supposed to come out of the hole where the knock sensor is... Then im assuming I have a cracked block or blown head gasket... Again. But lord I beg of him please dont be.

**Smittro** · 12-31-2011, 04:21 PM

Originally Posted by flybird

Job is done. I got the new knock sensor on. Only thing is though, oil didnt come out of the knock sensor hole, antifreeze/water did. ATON did. So I put anti freeze back in the car and turned it on. I noticed it started getting hot QUICK. About 230 degrees farh until I killed it.. Im thinking theres gaps thru the engine where it needs water so im going to let it cool down and see if she needs more anti freeze.

If water was NOT supposed to come out of the hole where the knock sensor is... Then im assuming I have a cracked block or blown head gasket... Again. But lord I beg of him please dont be.

No.. you are correct, I apologize.. I was mixing thoughts.. My bad..

You'd think after 20 years of messing with these and having manuals and schematics for these I'd remember correctly.. Derp! Again sorry about that..

**flybird** · 12-31-2011, 05:00 PM

No sir, its okay. I appriciate the help on everything. you are basically my guidance to the v6 engine bulid to everything I dont know.

What I do know is it sure was a pain in the ass to get to the sensor and take it off n put the new on.

**flybird** · 01-02-2012, 08:33 AM

Alright guys I have no idea whats going on.. Knock sensor bank 2 keeps showing up on my comput.. Ive replaced it, ive had the code erased and it comes back. I dont believe I did anything wrong. But I cant pass the inspection (which is now 3months out)..

**Knight** · 01-02-2012, 09:23 AM

I would follow the wiring back, checking for any breaks, grounds, or shorts. Are you positive you don't have any engine knock?

**flybird** · 01-02-2012, 10:24 AM

The engine is new. Going on 5,000 miles. everything about the engine is new besides sensors. I never hear a knocking noise...

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In the pictures there is the new knock sensor put in place. You can see that its not fully screwed in, but its as far as i could get it in with a 7/8 wrench. This space was ridiculously tight..

Also do you see the black washer thats loose on the white connector?? It had come out of place when i was almost done screwing it back on. Is this bad that the washer is out of its place?

I have cleaned the connectors today and i filled up on a higher grade of gas.. I read somewhere that if you use bad low grade gas it can throw the knock sensor off.