Knock in Lift (PFC + DLI)

[kaioshin]

Hey folks,
I've been trying to tune out some of the knock I've been getting during lift with the DLI. I've retarded timing (4-6 degrees) and added gas (4-12 steps) but I'm still seeing about the same amount of knock (~40).

Am I just not making big enough changes or am I just missing something?

Thanks.

[Smaay]

Are you N/A or boosted? if your are N/A then ~40 is ok..its a little high but still within a safe zone...email me the map you are using and ill take a look at it for ya. eodninja6@aol.com just make it obvious who you are

[kaioshin]

Originally posted by Smaay
Are you N/A or boosted? if your are N/A then ~40 is ok..its a little high but still within a safe zone...email me the map you are using and ill take a look at it for ya. eodninja6@aol.com just make it obvious who you are I am N/A. The problem is that I have a HPDE this weekend and I'll prolly be in lift for 20 minute intervals so I want to make obsolutely sure my engine is running without problem.

Email is off. Thanks for taking a look.

[00silverGTS6spd]

along with the timing and fuel valve timing can change your knock levels too.

[kaioshin]

Originally posted by 00silverGTS6spd
along with the timing and fuel valve timing can change your knock levels too. yeah, I tried retarding that a few degrees too, no change.

[phaqgm]

Perhaps your knock sensor is going bad, or it could be picking up timing chain slap. How many miles are on your engine? Did you ever have your engine rebuilt? If so, was the head milled at all?

[CIN]

Take a look at the logs. It could be picking noise when you change gears. If it is only a spike for a split second and not sustained knock like what usually happes at 5-5.5k then I would not worry about it since it is probably not knock.

[00silverGTS6spd]

with the valve timing you can get resullts from going up or down. it's not quite like timing. someareas you need to go up others down. whats reall confusing is some areas make power up AND down. however one direction usually causes more knock then the other.

best thing to do is play with it on the dyno.

[kaioshin]

Originally posted by phaqgm
Perhaps your knock sensor is going bad, or it could be picking up timing chain slap. How many miles are on your engine? Did you ever have your engine rebuilt? If so, was the head milled at all?
Hmm... That's something I never considered, though I not sure that was the problem. B/c I could hear the knock coming from the engine. Especially under load at higher rpm. The engine had about 145k on it and was never rebuilt. The only time it had ever even been cracked was to have the lift bolts replaced.

Doesn't matter too much though as I most likely spun a bearing due to oil starvation. :(
Originally posted by CIN
Take a look at the logs. It could be picking noise when you change gears. If it is only a spike for a split second and not sustained knock like what usually happes at 5-5.5k then I would not worry about it since it is probably not knock.
Nope, I would get knock from 6k to 8600. Not just when shifting.
Originally posted by 00silverGTS6spd
with the valve timing you can get resullts from going up or down. it's not quite like timing. someareas you need to go up others down. whats reall confusing is some areas make power up AND down. however one direction usually causes more knock then the other.

best thing to do is play with it on the dyno. Cool. I will keep this in mind when I get more dyno time after I get the new engine in.

[00silverGTS6spd]

wow funny story,

I was having the same problem as you. and I would also get strange spikes in the A/F ratios right about the time the worst knocks would occur.

my problem turned out to be a fuel pump thats going bad. it's either the fuel pump or the pressure regulator or both. so I'm gonna replace them both.

other symptoms I had along with the high knock levels and having to increase the fuel input, anytime I would hold a steady rpm at 4K or higher the car would start to hesitate and jerk. very subtle at first but now its really bad. the fuel pump even sounds like crap. it also had a problem with cod starts sometimes.

just thought I'd share that since I just wasted 4 hrs trying to tune it out only to find out it was the fuel pump causing the problem. no matter how much fuel I added the pump wasnt pumping so I still got knock. lol

[kaioshin]

Originally posted by 00silverGTS6spd
wow funny story,

I was having the same problem as you. and I would also get strange spikes in the A/F ratios right about the time the worst knocks would occur.

my problem turned out to be a fuel pump thats going bad. it's either the fuel pump or the pressure regulator or both. so I'm gonna replace them both.

other symptoms I had along with the high knock levels and having to increase the fuel input, anytime I would hold a steady rpm at 4K or higher the car would start to hesitate and jerk. very subtle at first but now its really bad. the fuel pump even sounds like crap. it also had a problem with cod starts sometimes.

just thought I'd share that since I just wasted 4 hrs trying to tune it out only to find out it was the fuel pump causing the problem. no matter how much fuel I added the pump wasnt pumping so I still got knock. lol
Hmm... that would make sense considering the mileage on my car. Though I kept an eye on Injector Duty cycle and max was around 89%.

[00silverGTS6spd]

might wanna have it checked JIC ;)