Getting some knock...

[Chrisssssssss]

Hey all,

So... I have been trying to chase some knock. I will tell ya what is happening. I will post my scanmaster readings tomorrow when I have a chance to actually write them down. I will be as thorough as possible so that I can get as much info as possible and maybe if I can figure it out it will help others maybe with the same problem sometime. I have tried to search and see what is said about my issue and spent a lot of time reading. Here's what the issue is and what I have done... Sorry for the long post, but I wanted to be as clear as possible so it may help pinpoint the issue and what I have done to resolve it. Any and all suggestions welcome.

I have been having some knock issues - when I get into boost on the upswing mainly - like as in when it first ramps up as boost is climbing. For example if you floor it and as it goes from about 1psi to 14 psi (I have a pillar mounted autometer boost gauge) - I can hear the engine ping or I hear some sort of knocking noise that I can't quite figure out where it is coming from. It then will set off the knock sensor and then give me as many as 10 degrees of knock... Usually somewhere in the 2-3 degrees mark. This usually comes as it ramps up, but as it settles down at 14ish psi I settle at about 0.9 degrees of knock. I have a chip burned for 91 octane that matches the injectors (37.5 # i think) It is a thrasher chip but I am using 94 octane all the time. I live in Canada and can get real Chevron 94.

I have notices these scanmaster readings. When my highest knock is recalled with the button, I am usually sitting at ~.832mv at 2.9 degrees of knock. This is a common recall number.

When I am in wide open throttle, I am usually always around .830-.840mv still showing some knock.
My IAC's are usually low single digits like 2-3 in park
My cc's don't go up at all when in park, nor really much at all... sometimes they will go when I am off and on the throttle. It is very sporadic if they count up. What causes this?

So... Here's what has been done to try and do a spring cleaning and see what kind of improvements they make. All specs and OEM replacement parts as per spring cleaning checklist.

-Changed oil (no improvement)

-changed spark plugs - (helped with smoothing idle, but still no improvement to knock)

-changed wires (no improvement)

-replaced the fuel filter (no improvement)

-increased fuel pressure (a bit of improvement) but I went through a full tank of gas in like 100 miles - so I backed it back down. I am gonna get a fuel pressure gauge and see exactly what is is set at and set it right. I haven't got one yet. That is next.

So - here's what I am gonna try next:

-check all vac lines and replace most of them - I heard spraying carb cleaner around them may help find leaks?

-my turbo screws keep loosening out of the turbo housing out to the downpipe. I replaced them and used new ones but they keep loosening. I used copper gasket stuff as the gasket, but the screws keep loosening. Is it safe to use some sort of thread locker on the cast turbo bolts? thoughts?

If you have read this far. Thanks for staying tuned...

 

[NorEaster]

What speeds are you seeing the knock at. Hit the both buttons on the Scanmaster and it will give each speed the lowest mv and the highest kr was seen.

 

[Chrisssssssss]

^ I will look into that and write it down.

Let me know if this means anything: my mv on the o2 sensor is always in the high .800's when I get into it, but when I am warmed up and in drive, the mv is around the 850's when it is idling, and then it goes down in the high 600's when it is stationary for a bit.

also the cc's don't count when it is in idle or park. Only when I am on the gas.

I am gonna write down all the numbers when I drive it tomorrow.

 

[bogies87]

Imo, if you havent replaced the o2 sensor it should be done. Cross counts should rise and fall (cycle) from 0 to (cant remember) 200.?.. in so many seconds. (I know i am pretty specific) point is if its not cycling it will need to be replaced. Or if its not cycling fast enough (lazy).
I would also look at updating your chip. Thrasher is an older model. Things have changed and so has technology. Believe it or not some of our chip burners (Bob Bailey, Turbo Tweak) have spent many hours, days or years refining fuel maps, timing curves, etc.etc. and something as simple as changing the chip could cure your problem.
See what you think...

Sent from my SCH-I535 using Tapatalk 2

 

[SHADOWII]

Imo, if you havent replaced the o2 sensor it should be done. Cross counts should rise and fall (cycle) from 0 to (cant remember) 200.?.. in so many seconds. (I know i am pretty specific) point is if its not cycling it will need to be replaced. Or if its not cycling fast enough (lazy).
I would also look at updating your chip. Thrasher is an older model. Things have changed and so has technology. Believe it or not some of our chip burners (Bob Bailey, Turbo Tweak) have spent many hours, days or years refining fuel maps, timing curves, etc.etc. and something as simple as changing the chip could cure your problem.
See what you think...

x2-replace the chip w/BB or TT

 

[we4Mateo]

^^^^^^^^^^^^^^

x3...if you still have knock after the chip change then you can at least lower timing yourself so it goes away.

 

[Chrisssssssss]

Ya, I think my next upgrade will be chip first along with 02 and checking fuel pressure.

 

[Chrisssssssss]

soooo... I looked in my spare box o chips... and low and behold! I found a TT 5.6 chip that is programmed for my combo. The previous owner (my dad) put back in the old chip because he said that the car had less knock then when it had the TT chip in it. I have been playing with the fueling and stuff... I just started tweaking it out now. I have added a bit more fuel in the 1-2 gears and it seems to be running stronger and with less knock now. I am still going to play with it and get a fuel pressure gauge and see where it is at right now.

Is there a method / procedure of tuning the car with the chip? like add fuel first? or timing? or? What is the preferred steps to tuning? I am ecited to see how much better the car will run when I have it tweaked a bit.

 

[we4Mateo]

This is a start...

http://www.turbotweak.com/forum/showthread.php?209-Chip-Instructions-for-Version-5-6

 

[Chrisssssssss]

Ok thanks! I checked that out. I bought a fuel pressure gauge and boy, was my pressure really high. I was running around 60 or so. I had no idea. No wonder my fuel economy was crappy. So I backed it back down to 43psi as everyone says. I am going to run it with it mounted on my windshield somewhere. I did verify that fuel pressure was solid and raised a bit when I reved it and let off to build boost and let off... but that was only at idle. I haven't verified it yet under load.

So I am gonna play around a bit with the chip and see where it goes. Now that I know that my fuel pressure is right, I disconnected the ECU and reconnected to reset it. I am gonna see how the readings go over the next day or so.

I am going to approach it this way: I am going to add fuel until I see no knock... and then play with the timing. Add some timing and see how it goes. Tune for the best timing. Back down if starting to see knock. Then lean it out to see if that helps. Is this correct? Or should I play with the timing first / then add or subtract fuel?

Thanks!

 

[we4Mateo]

Ok thanks! I checked that out. I bought a fuel pressure gauge and boy, was my pressure really high. I was running around 60 or so. I had no idea. No wonder my fuel economy was crappy. So I backed it back down to 43psi as everyone says. I am going to run it with it mounted on my windshield somewhere. I did verify that fuel pressure was solid and raised a bit when I reved it and let off to build boost and let off... but that was only at idle. I haven't verified it yet under load.

So I am gonna play around a bit with the chip and see where it goes. Now that I know that my fuel pressure is right, I disconnected the ECU and reconnected to reset it. I am gonna see how the readings go over the next day or so.

I am going to approach it this way: I am going to add fuel until I see no knock... and then play with the timing. Add some timing and see how it goes. Tune for the best timing. Back down if starting to see knock. Then lean it out to see if that helps. Is this correct? Or should I play with the timing first / then add or subtract fuel?

Thanks!

These cars like boost more than timing on today's gas. Get it to run well and not too rich, then add boost instead of timing, imo. As you add boost, you may then need to add fuel to compensate as the TT chip is static fuel delivery at WOT. You may be suprised with how much boost you can run on pump gas and low timing. If the AFR isn't too rich, it'll pull hard. It'll probably pull hard even if it is rich. You'll never know the AFR for sure without a tailpipe wideband or one you install in the car. Getting a WB doesn't make you a tuner, but it sure helps get a lot closer; in my case at least.