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Discussion Starter · #1 ·
ok, some of you may have read my "3400 knock/ping issues" thread, in which case upon some research and searching, i have discovered that im primarily sure that my egr being disabled is causing the knock! i never did state that my egr was disabled. SOO, who else here has done a 3x00 swap and disabled the egr? if so, any knock?

thanks!
cody
 

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rsisbetter said:
ok, some of you may have read my "3400 knock/ping issues" thread, in which case upon some research and searching, i have discovered that im primarily sure that my egr being disabled is causing the knock! i never did state that my egr was disabled. SOO, who else here has done a 3x00 swap and disabled the egr? if so, any knock?

thanks!
cody
No EGR here, and no knock ever. Get a wideband and see what kinda AFR your running.
 

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i dont think the egr would be responsible for your knock issue, did you have it disabled in the ecm or just taken it off?

does your knock happen only at cruise/light throttle or are we talking about under WOT?

i havent been using an egr valve for over a year now and the engine does just fine.
 

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The majority of the swaps are all running with the EGR disabled, since a lot of them got their chips from the same people.

If the EGR was removed from the vehicle or non functioning, but it wasn't disabled in the chip, then that could potentially cause knock, but that isn't your case (is it?).
 

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Discussion Starter · #5 ·
scott did my chip for me, and i had him disable the egr. no MIL's are present of any sort.

the knock is strictly at WOT, any gear, any rpm. i find that the hotter it is outside, the worse it is. but even at cool 60* nights, it will still do it. ALTHOUGH, if i slowly ease into the throttle to WOT, it will be much less likely to knock, but still will. im lost for options, :x . the only thing is, this winter i'll be able to pull the heads and see what kind of possible carbon buildup maybe in there, (one possibility). any input or options greatly appretiated.

thanks
cody
 

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rsisbetter said:
the only thing is, this winter i'll be able to pull the heads and see what kind of possible carbon buildup maybe in there, (one possibility).
Whoah, kinda jumping to conclusions pretty fast aren't we....

Get at least a datalog of what your car is doing. That should tell you right away whats going on with the knock and what your blm's are etc...., instead of tearing down the motor for something that is most likely tuning related.
 

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Discussion Starter · #8 ·
slowolej said:
Is this knock something you're hearing, or something you're seeing on a datalog / scantool?

strictly at WOT, any gear, any rpm.
This is an unusual combination for real knock. Nothing at light throttle, light load cruise?
hearing it, i had one of my dads friends ride with me (since i had never experienced or heard this type of boise before) he has done MUCH racing, engine building. first 5secs of driving, i mash it to make the noise, he says, "thats DEFINATELY piston rattle, from knock"

no knock under cruise or light throttle, only WOT any gear, any rpm. ALSO, in say 4th/5th gear, it will knock at initial WOT status, (going from cruise throttle, to mashing it), and after being WOT status for a few tenths, it will stop.

im going to get the ALDL datalog cable somtime, and get a datalog, theb post it up and see what you guys think.

otherwise, im not sure.

thanks much
cody
 

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from WOT it shouldnt be anything to do with the egr valve unless its sticking open on you.

3400's have sloppy pistons anyways but it usually clears up once the engine is warm and they expand a bit. what kind of fueling system are you using? its possible you dont have enough fuel coming through when you mat the gas.

did scott add any timing in your chip?
 

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Discussion Starter · #11 ·
treeZ24 said:
from WOT it shouldnt be anything to do with the egr valve unless its sticking open on you.

3400's have sloppy pistons anyways but it usually clears up once the engine is warm and they expand a bit. what kind of fueling system are you using? its possible you dont have enough fuel coming through when you mat the gas.

did scott add any timing in your chip?
fuel system; stock j pump closing in on 200k miles. m2 injectors. 3400 rail. 3400 (03' fpr). solid 45psi at idle.

cody
 

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Fuel pressure is too low

Do you have a vacuum gauge? Measure the vacuum at the manifold port... see what it is... I'm betting you have a vaccum leak which is running lean as shit and possibly causing your knock...

Or you got a shit motor... Which would suck, but hey, Atleast you wouldn't be done before me :lol:
 

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Discussion Starter · #13 ·
91berettagt said:
Fuel pressure is too low

Do you have a vacuum gauge? Measure the vacuum at the manifold port... see what it is... I'm betting you have a vaccum leak which is running lean as shit and possibly causing your knock...

Or you got a shit motor... Which would suck, but hey, Atleast you wouldn't be done before me :lol:
if i just barely activate the throttle linkage, it jumps up immediately to 50psi.
i have an autometer vac. gauge in the car actually. when i FIRST had it mounted on the pillar in a pod, i was getting about 19in/hg if i remember right, then, for whatever reason, as soon as i moved it down to exactly where the stereo would be, it went to about 21-22in/hg. i dont know why it did that, i figured since the gauge was now at level or lower than the source.
i literally JUST changed out the LIM, and plenum gaskets. the vac. gauge is always consistent. and the engine now only has 18k miles

cody

BTW: i had a couple questions too:
1. lets say i am running a very excessive amount of knock, there wouldnt be an MIL, UNLESS, it was related to somthing wrong with the circuit, right?

2.again, lets say i am running an excessive amount of detectable knock, wouldnt the timming be retarded so much, that i'd be running like a 20sec quarter mi.?

if thats the case, i have no MIL's, and the car still has mad power even under knock

cody
 

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rsisbetter said:
91berettagt said:
Fuel pressure is too low

Do you have a vacuum gauge? Measure the vacuum at the manifold port... see what it is... I'm betting you have a vaccum leak which is running lean as shit and possibly causing your knock...

Or you got a shit motor... Which would suck, but hey, Atleast you wouldn't be done before me :lol:
if i just barely activate the throttle linkage, it jumps up immediately to 50psi.
i have an autometer vac. gauge in the car actually. when i FIRST had it mounted on the pillar in a pod, i was getting about 19in/hg if i remember right, then, for whatever reason, as soon as i moved it down to exactly where the stereo would be, it went to about 21-22in/hg. i dont know why it did that, i figured since the gauge was now at level or lower than the source.
i literally JUST changed out the LIM, and plenum gaskets. the vac. gauge is always consistent. and the engine now only has 18k miles

cody
The m2 injector chips usually use the later 55psi regulator. That could be causing a lean condition at WOT. Maybe your leaning out due to that and getting knock.
 

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rsisbetter said:
2.again, lets say i am running an excessive amount of detectable knock, wouldnt the timming be retarded so much, that i'd be running like a 20sec quarter mi.?

cody
actually a 17ish lol, on my first run down the track i had terrible "knock", my connector was cracked and retarded the timing badly, did a 17.3 :oops: :lol: :lol: :lol:
 

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Discussion Starter · #16 ·
88cavalierz24 said:
rsisbetter said:
2.again, lets say i am running an excessive amount of detectable knock, wouldnt the timming be retarded so much, that i'd be running like a 20sec quarter mi.?

cody
actually a 17ish lol, on my first run down the track i had terrible "knock", my connector was cracked and retarded the timing badly, did a 17.3 :oops: :lol: :lol: :lol:
well thats not the case for me then, shes still got mad nuts. :x
 

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I'm amazed at how many people try to tune without using something to watch what the ecm is seeing. It takes years of experience to even try to be good at it. You have spent more time posting about knock than it would likely take to identify the problem if you could get something to watch what's going on from the ecm's point of view.

CEL can illuminate if knock is detected and cannot be eliminated. The code assumes the sensor has a problem and is falsely indicating knock.

"piston rattle from knock"... <sigh>
Well, the guy's probably a damn good engine builder, but "piston rattle" is a condition caused by excessive clearance between piston and cylinder wall, and "knock" is a condition caused by fuel combustion causing excess pressure which cannot be converted into mechanical energy by the piston and crank and is instead converted to heat and sound energy. The have distinctly different sounds. Piston rattle can occur with the spark plugs disconnected, as it has nothing to do with fuel burning and has everything to do with the "fit" of the piston. Knock will rarely occur with the spark plug disconnected as it's caused by fuel and air reacting, which is usually started by a spark.

You don't need to remove the cylinder head to eliminate carbon buildup as a possibility. An old quickie trick is to use water to remove carbon. Get the engine hot, bring rpm to about 2500, and slowly pour a cup of water into the intake without stalling the engine. That will generally remove some of the carbon. It's tricky with a PFI engine but you might be able to use a piece of turbing on the TB to get the right angle to make this work.

For an absolute, guaranteed, sure-fire way to remove carbon buildup use GM Top Engine Cleaner (DO NOT use Sea Foam instead. It is no-way, no-how not the same, and I'll be glad to tell why if needed). Get a can of the spray version of TEC, and some tubing from an air shock "replacement hose kit." Get the engine warm and spray some TEC (about 1/2 can) in the TB while the engine is running. Immediately shut engine off, pull plugs as soon as you can, and using the long tubing spray an equal amount of the remaining 1/2 can in each cylinder. Replace plugs, let engine sit overnight, and start in the morning. Don't start it inside your garage! It will smoke very badly. Run the car until the smoke clears up then go for a drive. If there was any deposit buildup large enough to cause knocking, it will be gone when you're done.

hth
 

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Discussion Starter · #18 ·
i know what you mean about posting alot, but im trying to see if there is anything physical i can do to the car/engine to make it stop. i will get a datalog cable here, but first i need to get it, then i need to get internet on my laptop, and download the program. so it will take a bit before i get that done, once i do i will post it up. (its just weird that no-one else is seeming to have this problem, with a chip from pretty much teh same person, and no egr)

cody
 

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EGR doesnt work under WOT or idle..only during cruising

^just in case you didnt know and it wasnt posted yet (to lazy to read it all)
 
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