New revised lifters, knack sensor and still knock

[tsidrift1]

I just replaced my lifters with the 3rd gen revised lifters. I also have replaced the knock sensor. It drove great for the first few weeks. I am now feeling the same things in the car that I felt when I getting bad knock. I have logged it a lot and it still is reading like at most 2-3 counts which isnt bad compared to the 35-40 counts it was reading before. I am hoping it is not something more serious. I dont know what else would cause the same effects as knock other than knock. If any body knows what could cause similar characteristics, let me know,


Thanks,
Anthony

 

[andymoraitis]

Anthony,

I think what you were experiencing before wasn't necessarily "real" knock in the sense that the knock sensor was picking up lifter/valvetrain noise and pulling timing as a result. With 2-3 counts of knock, I would consider than much more valid and refer to it as real.

Since you have an upgraded pump, but stock injectors, you may be reaching the fuel limits on your current setup. Injectors can lose flow over time. To verify that the knock is real, turn the boost down in 1psi increments until it goes away. Also, pull your plugs and have a look at the their color as a whitish color would indicate a lean condition. Also look for metal flecks on the plugs that are a prime indicator of serious detonation.

To put your mind at ease, I actually tune for 2-3 counts. At that knock level, you won't pull timing and kill performance. As you progress in your tuning, keep that in mind and use that as the upper envelope of where you want knock to be. Treat it as the edge and you'll obtain the greatest performance without sacrificing reliability.

Let us know what you find when turning the boost down,

Andy

 

[ADrewzki]

Cheap/bad gas maybe? A very noisy valvetrain? Too much hot air? Have you ever run race gas in it and the problem went away?

 

[tsidrift1]

I never did think about the injectors maybe losing their flow. I will try to turn the boost down, and see what happens. I am only pushing about 19 lbs of boost right now. I am wondering if my cas is faulty. when I did the ignition timing, I set it to 5* BTDC and thats when it actually started to run funny. It was set at 10* Btdc before because I hadnt adjusted the cas since I did the timing a few weeks ago. The timing light was acting kinda funny also, every once in awile it would flash really fast and then back to normal. It would do it really quick. It runs awesome when the engine is cold, and when it gets warmed up thats when I feel it start to hold back a bit.

Keep your posts up guys
Thanks,
Anthony

 

[andymoraitis]

Anthony,

You bring up an interesting point on CAS issues. If you're trying to set it at 5 degrees and having issues, that could be the source of your knock (advancing timing over base too much). Running 10 degrees will certainly lower your knock threshold. I'd grab a new timing light and re-time the car for 5 or 7 degrees and see if that helps the situation.

Keep us posted,

Andy

 

[power=dsm]

i thought by giving the car more timting you increase your knock because the car is running a more aggresive base timing

 

[tsidrift1]

Well, the car actually ran a lot better whenit was at 10* BTDC. The only reason why I thought I would change it was cause the idle would misfire or choke a lot. Now that it is set at 5*, it still chokes but not as much. I think I am going to adjust the timing a little more advance like it was when it was running good. I dont understand why it starts to run bad once the engine is warm though? Oh and by the way, I am running 10 lbs of boost not 19, (typo).

let me know guys,
Anthony

 

[andymoraitis]

i thought by giving the car more timting you increase your knock because the car is running a more aggresive base timing

That's absolutely true. When I say "lowering your knock threshold" that means that it'll bring knock on sooner and take away more margin.

Make sense?

Andy

 

[tsidrift1]

To be honest, not really. I have learned a lot on these cars in the past year since i got my turbo model, but the timing and knock thing is still a little confusing to me. I will try to adjust the timing a little more advance as soon as I can and see what happens. I noticed today on my way home from work that when ever I hit the throttle and i hit boost no matter how much, and let off the throttle, it sounds like it is backfiring like the car is trying to catch up with the turbo or something. I have done pressure tests on it, I dont know how many times. The only place it leaks is a line going from my bov to the tee for my mbc, and the throttle body has a leak like inside it where the rod goes into the throttle body that connects to the throttle plate. I just hope that when I adjust the timing again my choke, misfire or whatever it is wont get worse, cause that really gets annoying.

Thanks guys for the coming posts,
Anthony

 

[andymoraitis]

If that's the case, try adjusting your timing to 7 degrees and see if it helps with some of your issues. In the interim, I know you have a logger and I'm wondering if the logger is bringing up any trouble codes that could be causing your driveability issues.

Some additional food for thought: The factory ECU runs a rich 9.5:1 A/F ratio in order to keep the motor safe under boost. If you're running a 190 pump, there is very mild overrun of the stock fuel pressure regulator. I'm wondering if you're not running into rich knock since your A/F could be below 9.5:1. Do us a favor and log a third gear pull at 10 psi, 15 psi and 17 psi and let's have a look.

Yell at us when you're all set.

Andy

 

[tsidrift1]

I am actuall maxed out at 10 osi right now. I get a little scared to do a pull with the car running like it does. What should I be paying close attention to on my logger? I have noticed on my logger that my fuel trims have went down, my low and mid trims are in between 85% and 90%, my high fuel trims sit at 100.2-9%. When I adjust my ignition timing again, I read that if you have a logger cable, to leave that plugged into the harness, not the cradle. Is that right? do I have to ground it out a different way or am I fine just leaving that cable hooked in there?

let me know,
Anthony

 

[Doug99RS]

What about carbon build up in the cylinders causing hotspots on the pistons? Have you run any kind of combustion chamber cleaner through the car? This worked wonders for Eclipse4x4 (Ed) on his GSX a while back.
Doug

 

[tsidrift1]

No I never have run any combustion chamber cleaner through my car. I thought about running seafoam through it, but I read that if you have high miles carbon might actually be doing you a favor by sealing up gaps. I read that some people put it in and the car ran worse because all the "sealing" carbon deposits were washed away. The car has about 205,000 on the clock so it is a bit old. The compression and everything on it is really good though. I bought the car from a girl. Maybe I should run some cleaner through it. What actuall is a hot spot on the piston, and how would that effect the performance I am getting?

Thanks,
Anthony

 

[Doug99RS]

A hot spot is basically an area that retains heat after the air/fuel charge is ignited. The problem comes in to place when the next cycle of air/fuel comes in to the cylinder. Compression alone generates alot of heat and can set off the a/f charge. That's how Diesels work. So, on a gas engine you get heat from compression, you also get heat from the ignition of the a/f charge but then there's residual heat left on the piston.

On a high mileage car or certain low mileage ones you will find high amounts of carbon. Carbon will retain heat. The carbon can actually set off the fuel charge from the bottom of the combustion chamber while the spark sets it off from the top. The two flame fronts cause vibrations, knock, and all sorts of wacky stuff as opposed to a nice, even flame front that is supposed to move in a certain direction at a certain speed.

There's alot of talk already about pre-ignition and detonation. Knock can be caused by both but my head hurts too much right now to try and elaborate on the differences.
Doug

 

[tsidrift1]

I might try and bite my lip and run the seafoam through it and see what happens. Hopefully it wont hurt anything in the head as far as the valves and seals and such.

Keep the replys coming guys,
Thanks,
Anthony