Just some interesting observations last night during a tuning session.

I've recently hooked up my MSD knock alert to my block and it's really opened my eyes to where I need to work hard to tune. As many know here, I have the typical "stage 3" setup with 8 injectors (440cc's being my secondaries).

The MSD Knock Alert allows me to hook up this box with a metered display very similar to a flashing light a/f meter to an extra stock knock sensor screwed into the back of the block. Anyways, as I drove the car, I noticed right away there was some knock. First off, I saw that I never had any knock up to 10 psi. Regardless of rpm or psi (less than 10), if I were less than 10 psi, there wasn't ANY knock.

However, once I ventured above 10 psi, I did notice my meter start to pick up things. Right at 10 psi, and 4000 rpms, almost every time the very first light of the meter would light up. Then it would go away higher in the rpm band. However, the meter would REALLY light up and go all the way to red just for a second on a hard shift at 15 psi. It wouldn't go that high at all though, except for above 15 psi.

After reading those, I messed with my settings on the EFI a ton. By going into the matrix and richening up the above 4000 rpm spots some, I was able to totally eliminate the +10psi, 4000 rpm one bar light up. I also richened up as much as possible the +15psi level. I was able to eliminate about all of the knocking there. However, I can still get it to knock some, if I do a quick downshift into 15 psi. It's not the gradual build to 15 psi that causes any knock. I still need to work with this to see if I can eliminate that knock altogether.

Lesson to be learned here: You may be getting knock and not even know it. My egt's have always been conservatively low. I want to hook in my datalogger next and see if timing is being pulled at all by the stock ecu when it detects this knock. BTW, I still have another brand's knock meter for sale.

WOw, so how much for the MSD knock thingy.


-------jezreel
1998 GS with hrc stage 2, sfmu, ml, prokits, egt, boost gauge, apexi tt, haydans tranny cooler, costum dp, dr. uber groundwires, dynotune fp gauge. gst muff, turbo spoiler
Boostin since Aug 03.

nothing like driving with the windows down and the music low: i love hearing the turbo spool, swwwhhhttt!!!!
thanks for www.kaptainmyke.com for the sig hosting :thumbsup

I see Summit Racing sells it for $140. http://store.summitracing.com/partdetail.asp?part=MSD%2D8964

The one I have that's not summit that has a "brain" which allows you to adjust the sensitivity and one remote light, I can sell for $65 shipped.

But I don't want to make this a for sale post. I just wanted to know if anyone else has done anything to adjust their fuel/timing to account for knock at high boost.

Ya know Jason, I get the same thing at 15 psi on a downshift WOT run(i think you already know about this though). Not using a knock meter, but basically my own ears, I cant get it to knock at under 12-13 psi or so, EVEN running a rather "lean" A/F ratio around 12.3:1 or so..EGT's go up really fast at that A/F ratio, but it doesnt knock. Now, when i try to run 15 psi, right for a second at the downshift between 4000-4400 rpm, it knocks, and i run around a 11.0:1 A/F ratio! I just don't get it personally. MOst of us run 8.8:1 pistons, 93 octane fuel, and stock ignition advance(14-17 degrees, up to 20 degrees), and I would think we could get more boost out of the S16G turbo before knock.

I do have a theory though. I'm just wondering if the stock cams are limiting us here at high boost. I'm thinking the cam profile is not letting the motor breathe well enough at higher boost, and some exhaust reversion is contaminating the intake charge, thus superheating the charge, causing the small amounts of detonation. Its just a thought though..I just cant see how it can knock, esp for me running that rich of A/F ratio, timing, compression, and octane. BTW, i had around 4 gallons of 93 in the tank, then put in around 4 gallons of 100 Unleaded, and the knock was totally GONE. I estimate octane around the 96-97 area of the two mixed..I'm just thinking that we need a cam with more lift, and more duration, with minimal overlap. But overall, 15 psi is quite a bit of pressure, and as always, FLOW is GOOD, pressure is bad..

One more thought too, I wonder if the 034 can react fast enough to a really quick increase in boost pressure, such as going from 5th to 4th, at high boost WOT..??

Reversion? On a factory cam with 2.4* of overlap, on a 10cm2 exhaust housing, with a 2.5" turbo back? You're insane.

Originally posted by XtremeRS One more thought too, I wonder if the 034 can react fast enough to a really quick increase in boost pressure, such as going from 5th to 4th, at high boost WOT..??

That's exactly my thought. Perhaps we're seeing another inherent problem with using a MAP sensor versus a MAF. Who knows? I'm going to trying and raise the fuel more just before 4000 rpm's. I'm not sure what to do beyond that besides getting something to retard my timing.

thank the lord for my water/alcohol injection, i boost as much as i want on pump gas and not worry about knocking

occasional light knocking or pinging won't harm the engine, but obviously a heavy or persistent knock put you in a world of shit

edit: the spare other 4 injectors you have caused some sort of design flaw....*possibly* the fuel spraying in at 15psi for you is hitting a super heated edge on a valve relief or something. ususually the cutting tool leaves a sharp edge, which is pretty viable to super heating and maybe even hold in enough that it will start to glow (same for a spark plug tip). now heres my theory...your added injectors spray to close to the head and the added fuel may be hitting this glowing edge either before the spark plug or even after ignition, it is damn likely that another flame front will be on your hands

bottom line:

watch the a/f's, run good gas, and keep the boost as cool as possible because anything that will either increase heat or retain heat in the combustion chamber will promote detonation/pre-ignition, etc etc

edit 2:

Originally posted by JasonESi_T
I'm not sure what to do beyond that besides getting something to retard my timing.

surface ignition knocking (or what i described above as a possible theory) cannot be controlled by spark advance/retard


....just some thoughts

oh, another thing...whats your highest timing advance under WOT at 15psi? 14-17 and even 20 is weak from what ive seen and been working with this applies to everyone in this thread, inquiring minds would like to know

Its odd that you beleive that the fuel injector position might be causing this.

For one , he added more fuel, that somewhat fixed the problem a bit.

Second, his first mention of knock was not audiable, he picked it up via the MSD knock sensor (very sensitive, I want to ask about your settings to compare with mine jason?) . His second incident might have been audible , but again he mentioned that he noticed it through the meters L.E.D. display.

Just cause you cant hear knock doesnt mean its not there. I think this led to my stock block's death . After all 2 years on 10psi with the "stock" star stage 2 kit had to have knock. Just never heard it I guess.

Edit, I think water injection would be a good idea though. Josh send me some pics and specs of yours, I hight tap this into my intercooler sprayers.

Originally posted by turbo8u
your added injectors spray to close to the head

Too bad the added 4 injectors are further back from the head than the stockers. The stockers also point directly at the back of the valve. Nice theory. I'm sure Reader's Digest will like it.

Originally posted by DarkOne

Originally posted by turbo8u your added injectors spray to close to the head

Too bad the added 4 injectors are further back from the head than the stockers. The stockers also point directly at the back of the valve. Nice theory. I'm sure Reader's Digest will like it.

its a discussion dino, im discussing. all im saying is there could possibly be a design flaw.

you guys keep knocking though :D have fun

Originally posted by DarkOne

Originally posted by turbo8u your added injectors spray to close to the head

Too bad the added 4 injectors are further back from the head than the stockers. The stockers also point directly at the back of the valve. Nice theory. I'm sure Reader's Digest will like it.

hahah...true enough. They're not very close. In fact they're a good deal away. A lot of discussion, research and practicality went into choosing a good place to mount the secondaries.

I'd alos like to clairfy a few things. At this point, the knock I pick up is mostly noteable right after a HARD shift that punches the car to 15 psi almost immediately. I've been reviewing other cars' timing tables and discussions relative to this stuff. For instance, Evo's timing immediately drops to around 10 or so timing advance after a shift, and jumps back up to closer to 20 at WOT 7000rpms. Now, I'm not sure where my advance is right now, but in the past my timing advance has always been about 17*. Always.

However, I'm determined to go back tonight if I have some time to compare my knock meter to my datalogger's monitoring of my timing advance. Again, I'm using a second stock knock sensor wired to the MSD Knock Alert. Any other sort of knock sensor just doesn't mate to those threads. The threads in our block are a bit different and unusually hard to find a similarly threaded GM knock sensor.

This damn car and its challenges. First it's boost, then it's fuel, problems with clutches and now knock. Wheeee!

Yeah even my secondaries are farther up in the stream, on the upper plenum..very doubtful that placement is the issue. If its not exhaust contaminating the intake charge, then I just don't understand my EGT numbers being that high at an 11.0:1 A/F ratio at 15 psi..

As far as timing, once the map sees WOT(0 psi) it goes to 17 degrees, BUT when going WOT(TPS sees full open) timing starts at 17, quickly drops to around 13, then steadily increases to a max of 20 past 5500 rpm or so up to redline. I guess retarding the timng a few degrees at 4000-4500 at that higher boost pressure, may work better than just dumping in fuel. I did the same thing Jason, dumped in a bunch of fuel at that rpm, and i could feel the motor bog a bit with that much fuel...still pinged a bit too..We really need to log A/F vs RPM on a dyno, but even still, its such a fast, short ping, it may not even be noticable if its due to a sudden short instance of going a bit too lean..

Originally posted by XtremeRS
Yeah even my secondaries are farther up in the stream, on the upper plenum..very doubtful that placement is the issue. If its not exhaust contaminating the intake charge, then I just don't understand my EGT numbers being that high at an 11.0:1 A/F ratio at 15 psi.. As far as timing, once the map sees WOT(0 psi) it goes to 17 degrees, BUT when going WOT(TPS sees full open) timing starts at 17, quickly drops to around 13, then steadily increases to a max of 20 past 5500 rpm or so up to redline. I guess retarding the timng a few degrees at 4000-4500 at that higher boost pressure, may work better than just dumping in fuel. I did the same thing Jason, dumped in a bunch of fuel at that rpm, and i could feel the motor bog a bit with that much fuel...still pinged a bit too..We really need to log A/F vs RPM on a dyno, but even still, its such a fast, short ping, it may not even be noticable if its due to a sudden short instance of going a bit too lean..

What are your Intake Air Temps? Maybe it's time to get a front-mount :shrug ?

Originally posted by babybeclipse

Originally posted by XtremeRS Yeah even my secondaries are farther up in the stream, on the upper plenum..very doubtful that placement is the issue. If its not exhaust contaminating the intake charge, then I just don't understand my EGT numbers being that high at an 11.0:1 A/F ratio at 15 psi.. As far as timing, once the map sees WOT(0 psi) it goes to 17 degrees, BUT when going WOT(TPS sees full open) timing starts at 17, quickly drops to around 13, then steadily increases to a max of 20 past 5500 rpm or so up to redline. I guess retarding the timng a few degrees at 4000-4500 at that higher boost pressure, may work better than just dumping in fuel. I did the same thing Jason, dumped in a bunch of fuel at that rpm, and i could feel the motor bog a bit with that much fuel...still pinged a bit too..We really need to log A/F vs RPM on a dyno, but even still, its such a fast, short ping, it may not even be noticable if its due to a sudden short instance of going a bit too lean..

What are your Intake Air Temps? Maybe it's time to get a front-mount :shrug ?

Hahn universal FMIC, intake temps are around 90-100 degrees..thats not the problem :)

Originally posted by JasonESi_T
in the past my timing advance has always been about 17*. Always. However, I'm determined to go back tonight if I have some time to compare my knock meter to my datalogger's monitoring of my timing advance.

thats a good idea, and 17*....thats it for WOT? :wary

Originally posted by turbo8u

Originally posted by JasonESi_T in the past my timing advance has always been about 17*. Always. However, I'm determined to go back tonight if I have some time to compare my knock meter to my datalogger's monitoring of my timing advance.

thats a good idea, and 17*....thats it for WOT? :wary

Well sort of..it gets up to 20 in higher rpm. Yeah, it still seems a bit low really, when comparing other boosted 4 cylinder motors. Most run over 20 degrees, but each motor is different. We have a fast burn designed combustion chamber(Pentroof head, central spark plug), which doesn't need as much timing advance either..I'm curious to see what timing numbers you get Jason. I have log I can compare it to also.

i see above 20 everytime ive logged it, thats why i asked

Originally posted by turbo8u
i see above 20 everytime ive logged it, thats why i asked

Are you leaning out with a SAFC? If so, then yeah I can see why. If not, then hmm..

the SAFC doesnt actually advance timing *that* much....its when i added the water/alcohol injection is when i saw a big jump in timing advance at WOT. without water injection i was seeing anywhere from 17-19 at WOT

not bad, then the lack of some knock let the ecu feel cumfy with the advance IMO.

*checks inbox* still no PM or e-mail from josh on water injection....

Originally posted by Chamuko
not bad, then the lack of some knock let the ecu feel cumfy with the advance IMO. *checks inbox* still no PM or e-mail from josh on water injection....

*checks inbox* no news of the parts car

I adjusted my electronic map clamp to hold a little lower so that the ECU will give me a little more advance. It's working well. To date I only tune to my EGT's so I really need to hookup a knock and wbO2 sensor to the eclipse.

How long does knock last when you shift?

There's a lot of vibration added during and right after a shift. The knock sensor is nothing but a microphone and a computer to interperate what it "hears." If it's only lasting a second, I wonder if it could be something else. Have you check your datalogger and watched timing when your meter jumpes, does the ECU pull timing, like it's seeing knock?



Exile Racing Technologies: http://www.exileracing.com
So. All that's left, is everything - Jesse James

Originally posted by Michael_97RS
How long does knock last when you shift? There's a lot of vibration added during and right after a shift. The knock sensor is nothing but a microphone and a computer to interperate what it "hears." If it's only lasting a second, I wonder if it could be something else. Have you check your datalogger and watched timing when your meter jumpes, does the ECU pull timing, like it's seeing knock? Exile Racing Technologies: http://www.exileracing.com So. All that's left, is everything - Jesse James

See, thats what I was thinking at first too, that it wasnt really knock, but something else. I had around 4 gallons of 93 in the tank, then put in 4 gallons of 100 unleaded, and the knock was completely gone...Throwing in some higher octane fuel is the easiest way to see if it is knock or not..

The knock doesn't last long, but it occurs mostly on shifts that take it into 15 psi. Going merely into 2nd never does it and that seems to jar the car a LOT harder than 3-4 shifts.

I still need to compare my datalogger with the knock. I haven't had a chance yet.

Originally posted by JasonESi_T
The knock doesn't last long, but it occurs mostly on shifts that take it into 15 psi. Going merely into 2nd never does it and that seems to jar the car a LOT harder than 3-4 shifts. I still need to compare my datalogger with the knock. I haven't had a chance yet.

when josiah and i were tuning his car i actually got a good log of the ecu pulling timing because of knock...he had it a bit to lean but we got it all taken care of. best tuned NA 2gnt ive been in by far. datalogger + SAFC = sweet ass street tune

Just a little update.

As I've been tuning my car of late, I've been able to richen her up quite a bit on the high of of boost through increasing my scaler fairly high while leaning the matrix on the low end a great deal. Knock unfortunately is still present, but to a much smaller degree.

However, in leui of the knock, I'm just oging to have to spring for a wideband. Unfortunately, I can tell I can actually force my car to knock when it's too rich as well. So one can get rich knock AND lean knock. It's easy to detect lean knock though, because it tends to be much more severe whereas with the rich knock, my knock meter only goes over about 1 bar.

Anyhow, I think I'll be able to get this tuned with a little more work. With these 034's, it's possible to richen the mixture a GREAT deal if one desires.

Lastly, while I experienced knock in boost, I noticed that my stock ecu didn't pull timing at all, at least not immediately. I saw my timing on boosted pulls anywhere from 14.5 advance to 20 degrees advance and staying that way during the entire pull (with knock being present). I couldn't really figure out a pattern. It did seem to be about 17 degrees for the most part however.

you're not knocking enough for the ECU to pull timing

Originally posted by turbo8u
you're not knocking enough for the ECU to pull timing

I guess that's a good thing then! :thumbsup

Originally posted by JasonESi_T

Originally posted by turbo8u you're not knocking enough for the ECU to pull timing

I guess that's a good thing then! :thumbsup

yup :D btw...dude your cat is hot, ive never seen a 97 talon with a front mount before. you'll be at the shootout right?

Originally posted by turbo8u

Originally posted by JasonESi_T

Originally posted by turbo8u you're not knocking enough for the ECU to pull timing

I guess that's a good thing then! :thumbsup

yup :D btw...dude your cat is hot, ive never seen a 97 talon with a front mount before. you'll be at the shootout right?

Yep, I plan to. Hopefully my tuning issues will be resolved by then.

Yeah Jason, I get the same thing. I've also done some fuel dumping in at that pressure, and rpm, and have tuned it out pretty good, but it still is there. Just as info, acording to my AEM wideband, my A/F is under 11.0:1. The gauge blanks out because it only goes to 11.0:1 haha..Yeah its damn rich, but i'll be dammed if the motor likes it at that pressure. Prob not good for power, but what can you do at this point.

Our ECU's dont pull timing for shit when it see's knock. From the datalogged runs i have done, the ECU only pulled 1 full degree when it saw knock. A knock free run at lower boost resulted in timing starting at 17, quickly dropping to 14(ECU sees TPS at WOT), then steadily increased to 20 up top. A knock run started at 17, dropped to 13, then went up to 20, all in the same rate, ect..

The way these motors were designed, and with the alotted timing advance used with 87 octane, I don't think Chrysler expected for these motors to see much if any knock to begin with..in NA form anyway :)

Hey Mett, that a/f dyno chart that Scott posted before. Was that yours with the lean spot at about 4500 rpms and nice everywhere else? OR was that another Matt? ;-)

Will a wideband meter be able to pick up a lean spot as well as a dyno's wideband?

that was the other matt. we could never figure out why it would go lean around 4500 rpm. it was just a big lean spike.

Originally posted by JasonESi_T
Hey Mett, that a/f dyno chart that Scott posted before. Was that yours with the lean spot at about 4500 rpms and nice everywhere else? OR was that another Matt? ;-) Will a wideband meter be able to pick up a lean spot as well as a dyno's wideband?

Yeah, that was matt(matt_95tgs). I unfortunately can't datalog with my wideband, and that knock happens so quickly, its really hard to tell whats going on. I would think if you were on a dyno, and logged the A/F during a pull, it would show up for sure. I would have whoever does the dyno put the wideband in place of your stock o2 for the run, just to get a more accurate RPM reading. But, if you buy a wideband that can log A/F vs RPM, then I would think it would show up too. I know the PLX Devices wideband unit can do that, but its like 550-600 or something like that.

I'm pretty sure that I'm going to buy that Zeitronix model. It has datalogging software plus a ton of other options. I'll be able to datalog and do a lot of other stuff. Plus it at $279, it won't cost me an arm and a leg. I may get the display later on.

http://www.zeitronix.com/