well i dont know if any of you know, but i was getting a pretty frustrating knock retard problem on my car for the last little while.

well, me and Shane went out for some driving on saturday and did some datalogging and think we may have found the cause of my KR problem. around 4300 ish rpm i was getting some pretty bad knock. it was actually retarding the timing 5.5 degree, which is what shane had set the maximum knock attack rate to be. we tried everything to figure out the problem from putting in higher octane (94 from its current 91 octane) and left the timing alone. we tried backing the timing out, stiffer motor mounts since my lower one seemed to be in rough shape, and even put back the factory line pressure and shift speeds on my 4 speed auto. none of this seemed to help with the issue.

well shane had a few more things he wanted to try and i think we are on to something now. turns out the problem with my knock was this...
















doesnt look like anything really does it? well look closely at the intake... closer... see where its bolted to? thats the power steering pump bolt. see how its bolted to it? its metal on metal. well the knock sensor is right on the back of the block not too far from the intake... so here is what we figure was happening. the intake was resonating or vibrating at this particular rpm that we were experiencing my knock in. sounds far fetched doesnt it?

well we did a few runs that night. first run confirmed the knock was still there, and was most prominent (backed out the most timing) in first gear. in second and third, not as bad. these runs were done at full throttle and recorded from speeds of 0-60 mph. the second run, we stopped and unbolted the intake from the power steering pump bolt. we isolated the intake as much as we could from the engine at the time by putting electrical tape on the bracket so it may cushion itself from the tip of the bolt as much as possible. we also taped the intake to a power steering pump line as we had no zip ties or other means to make sure it wasnt moving nor did we had anywhere else to really attached the intake to.

we did another 0-60 run. the knock retard i was experiencing before was cut IN HALF! seems like we are on to something and hopefully when i find a anti shock/vibration mount we can do another run and see if its even less noticeable.

i'll keep you guys updated.



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

very interesting. my aem is mounted in that exact same spot... i chose not to mount it on the stud because i think it looks tacky...

so was the power difference noticeable?



Rollin' on question marks since 07.

well i dont know if the power difference would be noticeable just from changing the mounting location or isolating the intake from the motor for vibrations, but it can be the difference in adding additional timing or not. generally if the motor is seeing knock, one would back out timing, or at least not add anymore timing to the spark tables.

the reduction in the amount of timing this false knock is removing (remember, my knock was cut in half from 5.5 degrees removed to lets say 3 degrees removed) may lead to being able to add more timing to the motor. so far, my motor has loved every bit of timing we have given it. in tis range, we are currently only giving it about 25-26ish degrees commanded. with the timing knock out as it was at the full 5.5 degrees, it would only see about 20-21 degrees of timing. now with the KR reduced to 3 degrees or so backed out, its seeing somewhere in the 23 degree range.

now, the other thing to consider is the higher the knock, the longer the decay of that knock is. so when my motor was pulling 5.5 degrees out it would take (for example, not actual rpm as i dont have the logs) 750 rpm to bleed that timing out of the system. with the intake moved and pulling 3 degrees of timing due to the still some what false knock, it could now get rid of all knock in 300 rpm.

i also forgot to mention that considering that the last little bit of knock was due to there still being some vibrations from the intake as the intake was sitting loose in the engine bay (pretty much). and also, the intake temps were well over the 90*F range for the second run as it was unseasonably hot this past saturday.

so, if we can completely eliminate this false knock, we may be able to squeeze more timing out of my motor, as it seems to love the additional timing we give it, even when it still had the false knock. and before anyone asks, im not brave enough to disable my knock sensor and until we 100% prove its false knock i dont see shane considering that (i dont think he would do it even if we were 100% sure, safety first).

anyways, i dynoed the day after on the sunday and pulled 123.85 hp and 128.11 lbs-ft of tq. it was on a dynojet, and with the intake disconnected and zip tied to a power steering hose. by saturday it was too late to fab up a proper solution and add additional timing.

doesnt seem like alot of power, but the curves are nice and not very peaky.

anymore questions, i will try and answer. im sure if shane chimes in later tonight he may be able to give more details from the actual logs rather than me trying to remember what happened lol.



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

123whp with HPT and some bolt on's? damn how the hell did u manage a 15.6 with that? i could barely sqeeze 15.4's with my 5spd car that put down 151



Rollin' on question marks since 07.

its a nice flat power curve... i really dont know to be honest with you. shane has the tune done really nice, the car produces power the whole way through the rpm range, so the power is always there rather than just spiked for a nice max hp number.



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

numbers dont matter anyways, its the times you run that define things.

a 15.6 from an n/a auto cav is impressive, i dont care who yar.



Rollin' on question marks since 07.

z yaaaa wrote:numbers dont matter anyways, its the times you run that define things.

a 15.6 from an n/a auto cav is impressive, i dont care who yar.

thanks, and now with the knock a little bit more under control, the shifts a little faster (they were stock shifts when i ran my 15.6), and hopefully some traction, im hoping to get to a 15.5 but lower would be nicer as well



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

thought i would post up part of the logs...

Intake bolted to PS pup bolt - metal on metal
KR max is set to 5.5*

RPM MPH TPS% Spark KR

3509 19 100 25.5 0
3632 19 100 26 0
3716 21 100 27 0
3810 21 100 25.5 0
3901 22 100 25.5 0
4007 22 100 26.5 0
4107 23 100 26.5 0
4219 24 100 25.5 0
4327 24 100 24.5 1.6
4431 25 100 24.5 1.8
4537 26 100 25 1.9
4640 27 100 22 5.5
4741 27 100 22 5.5
4850 28 100 22 3.4
4965 29 100 25 3.4
5072 30 100 25.5 3.4
5165 30 100 26.5 3.4
5276 31 100 27 3.4
5386 32 100 27.5 3.4
5482 32 100 30.5 1.3
5580 33 100 31 1.3
5688 34 100 31.5 1.3
5777 34 100 31.5 1.3
5874 35 100 31.5 1.3
5964 35 100 32.5 0
6056 37 100 32.5 0
6150 37 100 32.5 0
6228 37 100 32.5 0
6315 38 100 32.5 0
6274 38 100 32.5 0
5777 39 100 32.5 0
5169 40 100 31.5 0
4485 42 100 27.5 0


Intake unbolted from PS pump bolt - isolated vibrations as much as possible
KR max still set to 5.5*

RPM MPH TPS% Spark KR

4249 38 100 26 0
4283 38 100 25.5 0
4318 38 100 25.5 0
4356 38 100 25.5 0
4388 38 100 26.5 0
4421 38 100 26 0
4455 38 100 25.5 1.2
4492 38 100 23 3.4
4523 38 100 23 3.4
4562 38 100 25.5 1.3
4597 38 100 25.5 1.3
4633 38 100 25.5 1.3
4670 38 100 25.5 1.3
4700 38 100 25.5 1.3
4738 38 100 25.5 1.3
4772 38 100 26 1
4807 38 100 26 1
4842 38 100 26.5 1
4878 38 100 26.5 1
4915 38 100 27 1
4948 38 100 28 0
4982 38 100 28.5 0
5016 38 100 29 0

you can see that the knock is dramatically less. i believe 26.5 or 27 degrees is full timing in that range. also, both runs saw intake temps well over 90*F, which could have been the cause for some of the knock.



you can also see from this dyno sheet that there is a slight dip in both the power and tq curves (more so on the blue lines) around the particular rpm that the knock is occurring. the runs were made with the intake zip tied to the power steering pump line, as there was no where else to attach it to.




1997 Cavalier Z24 - 15.647 @ 88.02 MPH

wow...

so do you think a rubber washer mounted under the PS bolt in-between the intake tab and bolt head would cure the problem???

i have no idea if my car is having this same problem, but it most certainly could be....which could explain why its such a slow POS.



Rollin' on question marks since 07.

i tried that... i took the power steering bolt out and mounted the intake like so...

Head --- PS Pump --- Wire Grommet --- Intake Bracket ---- |NUT| -------

where Head is the engine head, PS is the power steering pump, Wire grommet and intake bracket is self explanatory. the "---" is the bolt and threads of the PS pump and the "|NUT|" is the nut thats stuck in the middle of the threads on the PS pump bolt.

the problem was i still had metal on metal contact with the intake and the PS pump bolt. im sure you can isolate this more by using two grommets or rubber washers. the other thing that i was mentioning to Shane (the tuner, his logs of my car) and John Higgins who contacted me through PM is that when i would tighten the PS pump bolt without the intake and grommet in the way, the bolt felt like it got tighter than when the intake bracket and grommet where in the way. so, its possible that the vibrations are also caused by the power steering pump itself. im not about to go remove the PS pump to verify this... make fun of me if you will but i like my power steering and its a PITA to remove it just to test this...


the reason why your car could feel like a dog like you said is the decay of the knock.

in the first log with full 5.5* of KR, it takes 1500 RPM from when i start to see knock to when it is fully gone from the system. through that 1500 RPM, im pulling either stock or bellow stock timing...

in the second log with the 3.4* of KR, it takes 460 RPM for the knock to fully dissipate, which is about a third of the time of the first log.

ive got a proper female-male anti-vibration mount on order from Brafasco, which if you havent heard of them they are a fastener supplier. the mount is costing me $13 CDN, which is alot for one of these but its probably because of the thread on the end of the PS pump bolt (6.00MM X 1.00). i tried doing it with a coupler nut and the male-male mount that came with the intake, but it sticks out too far and the intake pipe comes too far away from the rubber elbow off of the throttle body.

it may be a week or so before i get the mount. since i only needed one, they were going to through it in with other orders to meet the minimum required order for that particular supplier.



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

all right... when you get it just post up pics (or gimme a link of a pic???) so i can see what your talking about.

if it works... i'll probably buy one.



Rollin' on question marks since 07.

I had the same issue with knock.
I was losing power with up to 5 degrees of knock after datalogging in the 1/4 runs at the track.
At the time, I was running 87 octane in the car and never really thought much about it.
Since I don't have HPT, decided that I'd try to use some 93 octane gas to quell the knock somewhat and yes, it worked.
The next time I datalogged on an abandoned road near the house, I witnessed less than 2 degrees of knock with no more issues of knock in the 5 degree range again.
So now, I'm strictly using the 93 octane gas without ever thinking about using the 87 octane again.

But your findings are pretty impressive in how you related the intake hookup to the power steering and that being the cause of your knock issues.
Great work and good times at the track too.

Oh, and I'm also running about 22-24 degrees of timing at wot with a factory tune. I'm sure that with HPT, I could improve that and my times at the track.



Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!

the idea to look further into the intake mounting was shane's. im just posting up his findings cause i know he doesnt come on here much except to look around and see if im making an as of myself...lol.

we tried the octane idea as well. i threw in 94 octane, which is the highest available here in ontario from the pumps. we ran the same tune witht he same timing, didnt help any at all. thats when we knew that it must be phantom knock...



1997 Cavalier Z24 - 15.647 @ 88.02 MPH

i went from running 89 to running 92 all the time and it didnt feel a damn bit different, didnt run any better anyways. the only reason i did that was because i was told i would need to as my timing was bumped a little via HPT. (shifted did a mail order tune for me)

i would really like to get a datalog on this biotch and see whats going on, i actually think the tune may have hurt my performance



Rollin' on question marks since 07.

ok... so what if you have solid engin mounts(RK mount) wouldnt the vibs from that give KR?


Kill list:03 eclipse, 06 GTO, 04 Mach 1 Mustang

not necessarily. the KR sensor picks u harmonics in the block. if the solid mounts were causing the detonation in the cylinder to be perceived by the KR sensor as knock, then yes.


1997 Cavalier Z24
Bomz Short Ram Intake
Vibrant Cat-Back
KYB GR2 Struts
Goldline 1.75" Springs
RK Sport Upper Insert
RK Sport Lower Dogbone
Custom Tune by Shane @
innovativetuning@rogers.com

15.647 @ 88.02 MPH