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Discussion Starter #1
hey, i just finished the break in on my fully built engine and started going in to boost, i'm running 11lbs on my gt3076r and started datalogging, initially my fuel was too lean and i hit 9lt knock and 4.5st, after adjusting the fuel to a solid 11.7 across the rpm range i got it to 4lt and 4st, now nothing i do will kill that knock, i pulled 6 degree's of timing and that did nothing, i put in 2 step colder plugs as i was running the stock ngk's, that did nothing, i've added extra fuel, still 4lt and 4st from 3k rpm and up, i have bc stage 3 cams and adjustable gears is it possible one of my cams is a little off screwing with my timing and causing knock?
 

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I'm having a similar problem but I have other issues going on. I was reading somewhere that it's not uncommon to experience phantom knock on a forged bottom end. I was getting 2.5st on like 14lbs at about 4k-4.5k rpms (let off when knock started) but when i turned the boost down to 10psi i didn't experience any knock although i really didn't do many test runs yet. I haven't logged for lt knock yet. On my stock engine i never used to get any knock even at 22lbs on a Garrett 60-1. What internals do you have? I'm running cp 8.5 pistons and bc rods. Is there anything rattling around your engine that could be causing the knock sensor to pick up knock? I know how you feel though just another road block it seems like.
 

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What are you tuning with?

With a fully built engine it is possible for the noise to increase as you have changed the noise profile of the engine due to the forged pistons. You need to do a baseline run from low rpms in third or fourth gear with 0 boost and some mega retarded timing. Log your knock voltage as fast as you can. If you have the ability to view the noise profile you will notice that it starts off near 0 and then increases with rpm. Depending on your tuning device you need to set your knock vs RPM threshold to about 15-20% above that line.

For instance if you have 1.0V of knock volts at 4500 rpms in a known "no knock" condition I would adjust your knock calibration table to 1.15-1.20V. This means that if your knock volts are 1.15V or below you are not knocking. If there is a spike above that threshold a knock condition has been identified and the PCM will pull timing/add fuel accordingly.

No please don't adjust your table that high. 1.0V of knock volts is way too high for most setups. You need to tune your knock table to your car.

Here is an example of me doing a short run logging knock volts:


In the bottom there is knock volts and knock retard. You can see that when the knock volts spike the timing is retarded and fuel is added. Unfortunately my table is too sensitive and even though the knock volts line is relatively flat with no obvious spikes like the first one the EMS is still pulling timing and adding fuel. I have since changed my tables so that condition will not happen.

HTH
 

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Discussion Starter #4
I'm running eagle rods, 20 over 8.5:1 je pistons and tuning with an intune, the only real noises coming from the engine are the timing belt tensioner makes a little noise, I have an exhaust leak where the downpipe meets my exhaust system that is pretty annoying, and of course while I'm at wot @ my 10lbs of boost there's the open wga dump, which come to think of it the knock only shows up when I'm at full boost so maybe that has something out do with it?

I'll have to check my pid's and make sure the knock voltage is being recorded and take a look at it, I would love to just put this thing on a dyno and get it tuned 100%, but with all the money into this build an $800 tuning trip just can't happen.
 

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^^+1 That too.

I am running Arias pistons with around a 3.5 thou piston to wall clearance. As you can see in the graph above my noise floor is still very low with the exception to the two little spikes which were probably minor knock. My car definitely has piston noise when cold but goes away for the most part once the temp reaches about 150-175F. Once it is fully warmed up it sounds like any other engine.

You don't really have to log knock voltage while driving. I would log RPM and Knock Volts as fast as you can. Start the car and let it warm up. Start logging. Slowly increase the rpms with the clutch out in neutral to as high as you feel like going. That should be enough to get a decent noise profile without jacking your tune up by fiddling with your timing. The noise should increase by RPMS and that is your no-knock noise barrier. Theoretically anything over that could be considered knock. It would be wise to add 15-20% to the voltages as you don't want a random noise event to pull massive timing.

Here is another knock log showing suspect spikes:



Notice how the spikes are above the rest of the noise? That was more than likely knock. You can also see how the noise floor gradually increases with rpms. IMO I was running waay to much timing at this point.
 

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Discussion Starter #7
ok i get you, i'll give that a shot tonight and see what the voltage looks like, and i'll check the knock sensor, i didn't realize that too tight of a sensor could cause issues as well, i'm not 100% but i think i just cranked it on good and tight, didn't think over tightening would cause an issue.

i've been working on this thing for 3 years so i have a fair bit of experience with everything on the car, but i was an old v8 guy for 12 years before that so some of these little things i'm not as used to.
 

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Discussion Starter #9
so i did a datalog at a stand still and this is what the rpm/knock voltage looks like, i did another quick run because i ran into a mishap today with a spark plug, i pulled my valve cover and found that my timing must have jumped atleast a tooth on the exhaust cam when it wasn't adjusted because i went from my gear being at zero to using all of the adjustment it had to get the cam back at tdc, runs amazing now as compared to before lol, but alas it didn't help the knock, still 4.5lt and 4st but i do still have to adjust the torque on that knock sensor.
 

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First let me say that I am not savvy with the DSP products but what you logged was spot on for what is needed.

You need to know at what rpm that peak is and what the voltage is. Then you need to adjust the knock threshold to something slightly above that number. I would do a couple of more logs from idle to redline kinda stopping at each 1000 rpms or so. This will increase the number of samples that you get at that certain RPM vice just it just winding up as fast as it can go. Take the average peak voltage vs rpms from the logs and adjust your knock threshold from there. Unfortunately I do not know how to do that with a diablo product. I'm sure Duster360, csmsach, or turbo666 know how.

IMO that high spike at max RPMS is probably why you are pulling so much timing. If you look at your tuner you should be able to see what the knock voltage is for that RPM. I am guessing that you are way above it. If you look at my first picture again you can see that even though my noise is very minimal the timing is still getting pulled. It acted correctly to pull the timing for those larger spikes, but there is no significant event further down the run that would lead to more timing retard yet the EMS kept on going. My problem was the sensor threshold and I believe yours is as well.

First retorque your sensor!! Then get to logging.
 

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Discussion Starter #11
the spike was 2.451v @ 6821rpm and ya, i'll set the proper torque on that sensor before i even take the time to datalog anymore, if that's screwing with my readings then there isn't much point in doing it
 

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Discussion Starter #13
ya it sits at .3-.5 at idle like you can see by the numbers in the corner, 1k rpm and .45v and judging by the graph pretty much climbs as fast as the rpm, the first time i did it at idle like that i got 2st knock and i can't remember the volts, this time no actual knock retard but still crazy voltage
 

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Discussion Starter #15
key on not running it reads 0.0039, i finally got it torqued properly on saturday and went up to a 10w40 oil for some better protection, damn iac i think is going out now because my idle is all over the place, i have to floor the gas pedal to get the car to start when warmed up, and idle was hanging bad, did iac and tps rewire, didn't change, changed out to iac and tps to a spare old set i had and the idle is pulsing 10 times worse and harder to start but the hanging rpm is gone lol, so going to change the iac back to the other one.

i also noticed when i was turning the car over after looking at the knock sensor voltage with the car off it went up to 4.8 volts, haven't had a chance to do a datalog yet though
 

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how many miles on the motor/

after 50k on my last rebuild, my air fuel/knock were all over the place.. haven't been able to go over 18lbs.. (use to hit 29 easy with e85)
pulled the motor yesterday, and have a new short block (rings pistons etc) going in.

leaving to much oil on the cyl wall can cause knock problems
 

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Discussion Starter #17
1k miles, I can boost fine, even at only 10lbs this thing feels like rocket lol it runs strong as hell and my afr's are good when I'm not idling, then they fluctuate around and the car's revs are all over, but I'm 80% sure that's an iac problem. for oil on the cylinder walls when I was installing the pistons I just used a light coat of assembly lube, I've pulled my plugs a couple times so far and they look perfect, not even the slightest sign of anything wrong, I can see a little oil residue on the piston tops through the plug holes, but nothing out of the ordinary.
 

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how did you break in the motor?
was egr connected to pul vac?
 

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Discussion Starter #19
I did what I found most people doing, prime the oil pump, do the first startup, run it to3k rpm for 15-20 mins, change the oil and filter, for the remaining break in I always varied the rpms between 1k-4k and downshifted constantly to keep the engine in as heavy vacuum as possible, I used break in oil for that warm up run, then did dino 10/30 with a shooter of the zddp engine break in additive for the first couple changes, then just 10/30, and just changed it to straight dino 10/40 after the break in.

And I don't have an erg, not sure how it is on the neons but I have an 03 pt cruiser gt so no egr
 
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