2001 Z06, only mods, vararam and oil catch can.

I am in CA and put in 3/4ths a tank of 91 octane. it detonates.
I added a can of 104 booster (if it even works) treats 25 gallons and still have detonation.

I got on it a little in 2nd down hill and it started ringing away.
it is 78 degrees out.

I changed the plugs and wires like 2 weeks ago. put in the delco iridiums gapped at .055 I think these are the ones that need to be gapped down a bit closer like .045?

Anyhow, I have seafoamed it twice before the plug change. I dont get it.

Ran it last night a bit in the 58 degrees and never heard a peep.
I picked the car up 3 years ago in the hot summer, and it was knocking when totally stock down to the plugs.

I am looking at doing some mods, and I would like this issue to be gone.
thinking about the juice. and I think I would have to go wet shot on a dedicated fuel system running meth or C16 race fuel.

 

Take it to one of the following (Andy@A&A / L.A.P.D / OC Corvettes) - and have them tune it out. You probably need a few degrees of timing removed (and some fuel added).

 

I'm having the same issue right now I just sea foamed the crap out of it but I still have an ultra conservative fat rich no timing tune in it intill we figure out how to get rid of it.

I think the 01's are gonna have more of an issue with this due to the oil consumption thus caking the top of the pistons and changing the static compression ratio. Anyways mines all cleaned out and I am gonna wait and put it back on the dyno this week.

Andy

 

I'd suggest considering that the knock sensors under the intake manifold might be going.

What I suggest is that they are not properly picking up the early stages of knock and by the time they react...you are actually hearing detonation.

if the knock sensors are working properly and early as they should...You would or should not be able to detect the detonation..

I believe if the detonation is noticible then my suggestion is to consider that the knock sensors are a day late and a dollar short.

Something about a TSB that states that there should also be a dam built to keep the knock sensors fresh but don't quote me on this part.

Hope this helps.

 

If I do this, what will I end up with.
I gather detonating is not helping me go fast, but when cold out it works fine. so will they be able to tune hot weather, but leave cool weather where it is?

 

whats this part about a dam? does oil get on them?
this whole engine is new to me.
I will be going in there soon. maybe I should just replace them.

 

When the manifold on my car comes off next weekend thats exactly what I'm having done. Labors about an hour... The two knock sensors under the manifold (look like to two black hockey pucks) are about $50 bucks each I believe.

While I have the manifold off I'm having the MAP sensor changed as well..(under 10 dollar part)

So I'm thinking an hour of labor...if that...and 110 or so in parts I believe...

The TSB that I'm referring to with building a dam is something to the effect of a RTV dam (I believe) that is built up to keep oil out of the knock sensor or it could be water...Either way there's an oil consumption issue or if the knock sensor gets water it somehow rusts and then doesn't work correctly..

Hence the "bad" knock sensors are not picking up some small amounts of knock and sending info to pcm for pcm to mildly correct...

What I propose is happening is that the knock sensors are not picking up the small normal amounts detonation and its not until its a big detonation that the sensors react and send info to pcm...

When the pcm hears that the large amount of knock it pulls a lot of timing...changes fuel etc...to deal with it and you and I get a sluggish drive off part throttle..

thats the theory anyway...and the one I'm working on this next weekend ...

HTH

 

let me know what you find out this weekend.
I am not sure when I am going to dive into mine. Still need to get all the parts.

 

I will report back.

Good to know I'm not the only one having this issue.

I've tried having it tuned out and it keeps occuring so the tuner suggested its a mechanical aspect thats causing this.

So far, seafoam procedure, new injectors, checked and cleaned all grounds, double checked for vacuum leaks, replaced pcv valve and hoses, replaced maf, plugs, wires, coolant temperature sensor.

Replacing parts can get expensive yet I believe (or should I say hope) the knock sensor should hopefully tag this.

No matter the results either way I'll report back.

 

Bill,

After I Sea Foamed my car was fixed! Took it out last night on the street with my Tuner and BAM! No more detonation! I Sea Foamed it three times, and then still sprayed Sea Foam Deep Creep through the injector ports and she's running like a champ now! We were able to add back all of the timing and then some and no Knock Retard.

Good luck buddy! Make sure you get the big smoke show from the Sea Foam or you didnt really get it in there properly. That is unless the piston tops dont have that much carbon.

Andy

 

Let me add one more piece of information.

I would suggest making sure each spark plug wire is double clicked on each coil. I don't understand why but for some reason I am finding that if I take take one wire off a coil and then make sure its double clicked my detonation goes away.

Add to that there is a tube on the drivers side manifold that runs by the number 7 cylinder plug wire...I shoved the part that runs back to the firewall up over some screw on the firewall so that the air tube? doesn't touch the number seven spark plug wire...and I have no more detonation..

I could be mistaken about this so I am still going to replace the knock sensors this weekend but it worked for me today to make sure all wires were double clicked on the coils...and move that air tube away from the number seven wire...(about 1/2 an inch space from wire where before it was touching..)

Maybe the spark was getting diluted? I have no idea..

Good luck and I'll report back..after the knock sensor replacement, I'm doing the map sensor while I'm in there too.

EDIT: KNOCK SENSOR wire didn't come in this week and I want to do the knock sensors and the wire at the time I lift the manifold. Will have to do it next week.

 

What do the scans look like?

I would really like to see the scan. An aditable "ping" would scare me to death!

 

DIXZ:

You could actually hear mine in the dyno. We shut off the knock sensors to see if it was false knock, and then you could start to hear it tick so we got out of it. Mine was audible. Since I have an 01 we figured there might be a bit of carbon on the pistons from the oil drinking issue. I have had a catch can on the car for about 10,000 miles but never got the old stuff out. Anyways she's been scrubbed down now and no more detonation.

Good luck

 

Andy
Question about your wording, What is Sea Foaming? Sounds like a piston top cleaner but I have not heard about it.
How many miles on your Corvette? Where did you buy it?
I can't hear pinging any more to many race cars. But my tuner did find knock retard last year on a dyno pull, 1000 miles ago. He had the feeling some thing was loose or vibrating casusing the retard.
I have an 02 Z06 with 17k miles.
Sid

 

Sid,

Sea Foam is a top end cleaner. My car is an 01 Z06 with 40,000 miles. I had too much Carbon buildup causing a change in the compression ratio we think causing it to ping, after cleaning it out it was all good. Do a search for Sea Foam on the forum and you should find some decent info. I found it at my local track auto.

 

I just did the knock sensor replacement, I did the GM top engine cleaner too at the same time.

I can say the car is running GREAT! I recommend that anyone experiencing a similiar scenerio consider having a qualified technician replace the knock sensors and also check under the valley cover. My buddy found twp pucks that should be tight on the underside of the valley cover at the underside of knock sensors were not on properly..(looks like they were loose and over time came off which would change the properties of the knock sensor design protocol? but not sure..)

We did the GM top engine cleaner at the same time.

Cars never run better!

I'd say doing both was a winner! ( I had done the seafoam a few weeks agao and although it helped, I kept feeling as if the issue was beginning to reappear again...)

Just my personal experience and I hope it helps others make a decision thats best for them.

 

Ahhhhhhh

Nothing better then a healthy Z06! I just took a blast down the street on the way home and 1st and 2nd gears were totaly useless Car finally hooked half way through 3rd and sounded really nice and crisp through all of the gears!

I am so glad to here yours is running well!

Congrats!

Andy

 

I'm am very curious what knock sounds like... I have a larginsh cam and LT headers... between the sewing machine noises from the motor, the exhaust pulses hitting the header collectors and the roar out the back I don't see how you could ever hear any knock.

 

Are you serious? A gearhead like you and you don't know what knock sounds like?

If you know what a car sounds like when it "diesels" after you shut off the engine, you've just heard knock. Knocking is severe preignition, or pinging, which is actually uncontrolled combustion. Hot spots in the combustion chamber combined with high static compression, poor fuel quality, too much igntion timing, high cylinder pressures and a myriad of other things can cause pinging and knocking. It's very damaging to engines and really beats up pistons and rod bearings. Very high temperatures are the result and things can also start melting like plug electrodes. In fact, plug inspection can tell you if you've got a problem with pinging and knocking.

Pinging can be identifed by a slight rattle on acceleration, and knocking is a severe rattle that sounds like the typical power-pulse "bang" emitting by a big rig diesel while idling. Hopefully this gives you an idea of what you DON'T want to hear!

 

^ My issue is that w/ the cam the normal sewing machine noise is more pronounced and I have a hard time relaxing and figuring out what is normal noises and what is or could be knock.