LT4 spark knocking when engine lugs???
 

when i'm driving say in 5th or 6th and just give it full throttle w/o downshifting...the car spark knocks real bad and i'm burning 93 octane...


any suggestions.....besides just downshifting, is the timing off

Re: LT4 spark knocking when engine lugs???
 

I'd say you are lugging the engine too much. Try downshifting.

Re: LT4 spark knocking when engine lugs???
 

yeah i do do that now but before the heads/cam change with my low gears i could run in 6th at town speeds and not get any knocking and i'm not sure why now that i'm getting knocking

Re: LT4 spark knocking when engine lugs???
 

Well your engine is not running as efficiently at lower RPM as it was when it was stock. Your power/torque curve has changed due to the different breathing characteristics from the cam.
Don't do that anymore. There is no reason why you should be running in 6th gear at "town speeds" unless you want a **** load of carbon buildup and like to change out plugs.

Re: LT4 spark knocking when engine lugs???
 

But isnt this a sign he is running too much spark advance in the high MAP/ low rpm ranges?

I have this same issue after my h/c. I agree that its not good to lug the engine. However, it seems like if the car's fuel/spark is properly tuned you should be able to floor it in any speed, any gear and not get knock, reguardless of how much the engine bogs.

Re: LT4 spark knocking when engine lugs???
 

So not true. Lugging is really hard on the engine. Add detonation to that and you have a recipe for early destruction.
If you want to floor it and not have to worry about changing gears, get an automatic.

Re: LT4 spark knocking when engine lugs???
 

well it's not like i drive around town all the time in 6th just wanting to floor it....what i meant by that statement was just to help you guys understand what conditions it happens in.....i rarley drive in 6th in town and don't anymore since i heard the knock, but was just curious if i needed to program it diff. or keep it the same, i thought i might pick up some hp if the car was not tuned in exact and that was the only way i knew how to describe it to you guys

so if i don't need another program in it then i'll just stay out of 6th until i get to about 70 now after the h/c swap b/c before i could run 6th no prob at 60mph now it feels like i have 3.42's again and 6th is useless.....i guess when i get a 12bolt in the spring i'm putting 4.56's or lower in it;


you know what really bothers me now.....i don't have many posts on here b/c i don't have time to browse on here anymore but have been around a long time and have owned alot of camaro's most of which are older........BUTTT what i don't understand about this message board anymore is I use to be able to ask pretty straight forward questions and get a good honest answer....but it seems now that if you ask any question that seems like your not a professional mechanic or have 5000 posts then ppl just want to make you feel like your a dumbass.......i mean i know if i don't want to downshift i need to get an automatic but that's not the point. I was simply asking the cause, the solution whether it be reprogram or nothing just dont' put your car in that situation it seems i get a answer like well you dumbass if you would downshift that would not happen. WELL that's not the brightest answer you could have given me. I just wanted a professional answer that would help b/c i know you guys prob know alot more than I. But maybe not!

Re: LT4 spark knocking when engine lugs???
 

It is hard to tell without knowing the engine rpm when your problem occurs but I suspect it is in the 1800-2400 rpm range. That is not uncommon with a cam and or head change like you did. The LT1/LT4 intake experiences reversion in that range and the cam aggravates the situation. I have had some success in smoothing it out by playing with the timing as well as the DFCO settings.

Re: LT4 spark knocking when engine lugs???
 

thanks alot....that was the kind of answer i was looking for, yes it is happening around 2500-3000. I thought about changing the timing but figured it would shave off some HP so i havent yet, do you have any idea how much the timing needs adjusting on it

Re: LT4 spark knocking when engine lugs???
 

What gears do you have now?
Just this thread alone the problem I see is you didn't explain yourself very well. You may not have gotten the brightest responses, but you didn't ask the question in the brightest way. Not only that but a lot of the questions asked on this forum have already been covered a thousand times and people who ask them again either aren't smart enough, or are too lazy to use the search function. I'm not saying you are that way. I'm merely giving an explanation to your exmaples.
No one called you a dumbass. You shouldn't be so sensitive. The best way for you to avoid such things is be as clear and concise as possible.

If you ever put your car on a scanner and you overwhealm the engine by flooring it in a low gear you will see stupid knock retard. If you really have a question as to whether or not your car is tuned properly then put it on a scanner and run it through the gears at the proper rpm levels (ie your shift points) to see how your fuel/spark/KR behaves.

Re: LT4 spark knocking when engine lugs???
 

i have 4.10's which were in my sig


i agree with you in some ways about the search function and ppl asking the same questions. I search everytime before i ask a quest. to be honest i have the search up right now on another page, but everytime ppl ask quest. on here there will always be someone who says SEARCH...well if we all searched all the time and never ask the quest. the board wouldn't exist any longer b/c you know as well as i do that that is prob. no quest. that hasn't been asked once before.....anyways i love this board better than KYfbodies which my friends run and all the others, but ppl need to lighten up some on here i think. Like i said if you don't have a bunch of posts i think ppl act like you don't know anything about what your doing and that's not true, i just don't have the time to set and watch the board all day or night like alot of ppl do and rack up there count. I've prob worked hours wise on more camaro's than alot of ppl on here but just need some opinions every now and then. anyways enough of the bull

i just now plain and simple that the car at idle cold hot whatever setting at a light anytime is putting out soo much raw fuel that it gives me a headache setting at the light. My buddy that does tuning says that the timing is high but when he retards it it will loose power but won't knock, i havent' made up my mind yet weather it's worth lost power in the upper rpm range for no S/K. But when i take off from a stop and rev it to take off a big cloud of fuel smoke exits the pipes.


btw *sniffles* i'm sooo sensitive :p

Re: LT4 spark knocking when engine lugs???
 

Yeah it sounds like you are running just a tad rich. How about a scanner? Have you seen what your 02's are reading? You really should check it out to make sure you are not sending too much fuel into the cylinders and risking washing out the rings. Has the car been on a dyno? This is the type of information that would be helpful.
I can understand the attitude thing. It's like that on about every board these days. These cars are much more affordable then they were just a few short years ago and younger people are buying them who like to throw the 'tude thing around. Hell I was even that way for awhile after I bought mine, but now am old enough to realize I shouldn't sweat the small **** in a tech forum. The kills forum is a different story though. :)
My suggestion is to definately get it scanned to see what's going on.

Re: LT4 spark knocking when engine lugs???
 

Almost afraid to answer this thread....... hopefully I'm not telling you something you already know :)

A question - can you actually hear the knock? If so, you may have a serious problem, since the PCM should be pulling timing and eliminating the knock before you can hear it. Does your programming include any sort of limit on knock retard or a reduction of the attack time?

Is your EGR system hooked up and functioning? Lugging the engine increases combustion chamber temps, and that increases the chances of detonation. The EGR system is there specifically to control combustion chamber temps under conditions like lugging the engine at low RPM in too high a gear. They do that to reduce the formation of NOx, but a fringe benefit is the elimination of knock.

Re: LT4 spark knocking when engine lugs???
 

My comment about an automatic was not even addressed to you. :shrug: I don't take post count into consideration. I look at the post content.

Re: LT4 spark knocking when engine lugs???
 

yes i can actually hear the knock....i would not think that he would have limited knock retard but i will check with him.

the EGR system is gone actually all of that is gone, he even bypassed the Mass Air sensor, and we put a pvc pipe in place of it.

the car has not been dynoed since the changes due to the fact that they pulled every race shop out of Bowling Green for some reason...i'll have to go to nashville which will be in the spring i guess before race season.

but i assume the car is excessiv. rich due to the fact that when setting ideling the car is just throwing out raw gas smoke not oil smoke