Can you post some logs or plots with wideband data? Also, your title says "my tune gone bad", was it previously running better?

*Edited, I did some reading on your past posts and your car certainly has some history Unfortunatly none of it shed any real light on what's going on? Seems more like another chapter in your ongoing mystery. Did you end up doing the drop in pistons or did the block get properly prepped? Any signs of oil in the combustion chambers? What do the plugs look like? Signs of actual detonation (speckles on plugs)? Engine oil will make 100 octane like 87 octane and could be responsible for your knock counts. I'm sure your dreading the thought. Maybe a leak down test is in order.

 

Plugs look normal. That's for sure. The block and head was machined and washed. Oversize pistons and valves. New crank, rods, pistons were all balanced.
The idling was worse than it is after the tune. But then again, we swapped my RC750cc for Precision 1000cc on the dyno and scaled them. The "my tune gone bad" only refers to the timing and knock.

 

Timing looks a little off for 100 octane.
My first venture would be to check the spark plugs. What do they look like and are they TIGHT? What plugs are you running. While your at it check to see what you hot compression is. If you can get back to me on the specifics I can give you a hand.
Also what year car is this?

 

He is running copper bpr8es I believe.
He should note too that this is not a finish tune. It was in the process of fighting with the knock counts it was getting in high boost. He was suppose to try different fuel and see what happens to the knock counts.

 

year is 2003. will check hot compression

 

Put some BP 92 in that thing and then see what happens, could sure be just some bad gas!

 

I think you'll need to do a leakdown to find out if it's engine oil causing the knock. Compression could still show fine especially if you have oil on top of your rings.

If you think the fuel could be causing the problem, try that first of course since it's easier.

*edit Check for oil in your IC piping as well.

 

nothing wrong with his timing map, conservative, yes its not perfect but nothing big time wrong, Fuel map is wrong wrong, looks like he is running way to lean I would imagine

 

The afr was in the mid 11's. I don't think thats lean for a 100 octane and timing that enough for pump gas.
The issue here is the knock counts. I let him out with the timing map that should be ok for 100octane until we can figure out whats going on.

 

since the motor has ben rebuilt, what is the compression ratio? did it change at all, i.e. high compression ratio? that would be an issue if your trying to run stock boost levels with higher compression.

 

How many miles ago were the valve seals done? Also you mention in a previous post, you had the head off a "couple of times for valve seals". Why more than once? Has the car had a leakdown test done since the valve seals were replaced?

Also, possibly improperly seated / sized bearings? What bearings did you use in your build.

 

huh? The engine was rebuilt. It was machined, all internals were balanced. Headwork: 1mm oversize valves (Ferrea) Also used Ferrea guides and seals. Everything on the head was put together at the shop. ACL bearings were used with the Eagle forged crank.

The couple of times I had to replace valve seals were before engine being built.

 

I can assure you there is no oil in the combustion chambers. Plugs are normal. everything else is normal. compression test turned out 180-180-178-180. compression ratio did not change with new engine.

 

* I just was looking in your 2008 build thread.

Engine oil in the combustion chamber reduces fuel octane and causes knock. Spun bearings cause knock too.

A friend just built a sleeved/forged VQ35 with a replacement crank and new ACL bearings. It had knock like what you are seeing, He pulled the motor removed the pan and semi inspected the bearings (jiggling on crank) no play so he reinstalled the engine thinking it was something on the top end. Still had knock and you could hear some noise coming from the center of the engine. He pulled the engine a 3rd time and pulled the bearings. One of the ACL bearings was the out of spec or the wrong size to begin with and was spun. He just called an hour ago and no more knock since 3rd bearing replacement.

I'm just throwing guesses your way, things to consider that could cause what you are experiencing. I certainly hope none of this is your issue, just possibilities.

Also, I was talking with my coworker and he said that sometimes when a bearing spins it will make the engine have 0 oil pressure and sometimes it will have high oil pressure depending on where the sensor and where the blockage is. I also noticed your high oil pressure thread although It looked as if others reported your symtoms as normal?

Nice looking build by the way. That head looks great.

You could just have a engine that resonates at a frequency that disturbs your knock sensor although your piston / rod combination is a known setup and since you had the block properly prepped you shouldnt have piston slap. Turn off the knock sensor or modify the filters maybe?

 

Yeah the oil pressure is normal. Service manual says 43-100psi @3500rpm. Obviously going to be more above that RPM. I haven't had any problems with it since I put it back together. Thanks for the compliment.

My tuner did modify the knock filters. Didn't help. Disconnected the knock sensor just to see if it would make more power, but ecu still pulled timing and still registered knock counts.(consistent 9 knock counts...I guess it's a failsafe thing) Maybe it is bad gas. My family owns a gas station so I guess I will run 92 octane and see if there is a change. Well, my plan to figure out if it really is the gas is to run factory map settings on 100 octane and log knock. Then run 92 octane and log knocks. I ran the factory fuel and timing maps on my remaining 100 octane and it still knocked. (1-4) but this was between 180-280 load and 2500-4500 rpm.
Knocking on 100octane with factory maps? Kinda disturbing. I will run the factory maps on 92 octane and see what happens.

EDIT:
Here is my log with 100octane on factory maps.
You can see that I still have knock from 2500rpm to 5000rpm. And this is 100octane with factory maps! Crazy isn't it?

I think I remember logging my car on 92 with factory maps with my setup right now last week with no knocks whatsoever. I'm gonna try again today and post it up.
http://www.quickfilepost.com/downloa...7aa357512e947a