Why I'm I Getting Knock?

[spadepro22]

Fully rebuilt motor, check profile for full list. Put new OEM knock sensor and set to 5*. Changed spark plugs today(bpr7es) and gaped to .028. Here are two logs of 3rd gear pulls. I let off when knock showed up. I've been working with a tuner, but is there anything else I need to check for?

 

[Sirnixalot]

check the overlap on the cams

i was chasing a similar issue and it turns out i needed to dial out some overlap

 

[rEclipserGST]

AFR was 10.9 on 3.8* of knock. Might be rich knock.

 

[spadepro22]

AFR was 10.9 on 3.8* of knock. Might be rich knock.

Yea, but is 10.9 that rich?

 

[rEclipserGST]

Yea, but is 10.9 that rich?

Not really sure how to answer that. There is a richer AFR if that's what you are asking. Unburnt fuel can cause knock. Looks too low a count of knock for it to be Phantom Knock.

So it looks like you need to tune a bit more. I've seen cars with stock fuel maps knock. Due to such a stoich factory AFR.

 

[LarryJoe]

I don't think 10.9 would amuse rich knock. Factory tune was 9.5 wasn't it?

 

[YZFR1]

Did not look at your log but in situations like these the best thing i could recommend is getting back to basics. Turn down boost and timing and see if the knock is still there. If so, than you got some major obvious issues to chase or it's just engine noise. If not, start bringing boost and timing back slowly to figure out where it is happening. Hope you figure it out.

 

[boost97gst]

Thats some strange knock. Its not rich knock cause youre simply not that rich. Youre sure you got 93 oct in there? I know thats a really dumb question but low octane would do exactly what im seeing. Your timing tables dont seem that aggressive though im not fully clued in on the 1gs. Im assuming you basically add 5* to anything you see correct? Perhaps Sirnixalot is right. Its worth a check. That sucks if thats the problem, whole lotta work there if you dont have adj cam gears. No personal experience with cam degreeing though.

Keep us updated cause thats some weird knock. Knock sensor looks good, not phantom knock. Maybe try backing youre base timing down 2 degrees and see whats up?? IDK

EDIT: Just noticed one small thing, the coolant temp. If my temp was over 210 i noticed a very small increase in knock but very small. May want to do a pull at a cooler temp like 185* just to test it out and see what happens. GL bro!

 

[turboglenn]

If i run mine on anything richer than 11.8 i get a lot of rich knock on E85. My car likes to be about 12.2 - 12.8 which seems scary at first until you've logged enough pulls on the fuel to start to drop the typical "safe zone" mindset that years of pump-gas will instill in you.

I will agree 110% about overlap, I have mine dialed to where the exhaust cam is +4* advanced and the intake is 2.5* retarded and it takes a lot of knock out of the engine with all other things like AFR and timing being the same, and with aftermarket cams this can be quite a variable as you can't be sure things are "straight up" just becase you installed them that way... also, check the physical cam timing, they are sometimes a PITA to get 100% perfect and somtimes even shops leave them at "close enough" and this can cause a noisy engine too... Still after 13 years i have times with the timing belt where i have to set it 4 or 5 times to get everything perfect and i dont' even have B-shafts to worry about

Also, there's a point where timing becomes a lot less favorable as a way of extracting power from airflow and compression ratio. when i got right at the 500whp mark i had to start really changing the way i thought about tuning for a daily driven car on e85 where you're doing more than making a pull and putting it away. I dropped my timing from starrting at a low 14-15* and rising to anywhere in the 19* and up range to where i now start out about 10* timing (anywhere over 26psi) and brin it up to a conservative 13-15* depending on the final boost and RPM (i have 13* at 30psi at 7500RPM) and then at 27psi i run 15* through 7500 and up, and it really does make a notable change in overall knock counts (which aren't everythign as engines get too noisy to worry about an oem knock sensor as well and i'd say that's anywhere over 325hp with aftermarket forged pistons it's almost a null point to look at the KS, and that's even with a J&S kncok system that's been tuned for my particular engine and to try to ignore piston slap)

OK, so maybe it's rambling a bit about KS's, but a tuner's member that's local to me and who's in the 10's as posted on this forum (i wont' out him by name because of what i'm about to say that he hasn't stated himself on here) but he has his setup ignoring the knock sensor all together until 7500rpm which i think he said it can't be set to ignore it past that in DSMlink... point is a good tune can light the KS up and not be harming the engine, it's just one more tool to use in an array of things you can use for feedback, butthe faster you go the more it really comes down to using plug readings and a real feel for the engine and car combo to come up with a good tune.. Just the same as why there's a lot of people running insane times that say there car's never seen a dyno, it just isn't always the best way to tune a car for a particular pplication (i would say a dyno would be more suited to road race/street use as just getting up into the area of starting your pull is a lot different circumstances than a drag launch to 1320 foot pull.

 

[boost97gst]

Glenn, can we sign a petition to get "dsm wiseman" under your name?? . I think we all learn something everytime you post. Just wanted to point that out.

Now, i didnt know the guy was running e85. In that case, yes, 10.9 is very rich. I mean alot of guys take it to 12.5. Im sure they are good tuners however.

 

[My1GLaser]

Are you running E-85? I am running 60% E-85 and recently richened up my tune to 11.6-11.8:1 and I started knocking, so I am putting it back to 12.0-12.2:1.

What CR pistons?

 

[spadepro22]

Na, I'm on 93 pump. Wiseco pistons 8:5.1

 

[turboglenn]

Glenn, can we sign a petition to get "dsm wiseman" under your name?? . I think we all learn something everytime you post. Just wanted to point that out.

Now, i didnt know the guy was running e85. In that case, yes, 10.9 is very rich. I mean alot of guys take it to 12.5. Im sure they are good tuners however.

ha..thanks, although never mentioned for reasons similar to the 33rd degree of masonry, to be honest it's really been a goal of mine to someday wear that badge I do post a lot of stuff that are just rants or opinionated BS, but try and keep it respectable and in the proper sub-forum, but i'm sure when the powers that be see fit, that day might actually come, i had hoped that eventually i could trade x amount of green rep chicklets for a rep star, but ewither way having been in the DSM game for so long and through so much in lfe i'm just happy to get on here and try and help others and share info that either isn't common knowledge or took me a long time to learn the hard way.

Are you running E-85? I am running 60% E-85 and recently richened up my tune to 11.6-11.8:1 and I started knocking, so I am putting it back to 12.0-12.2:1.

What CR pistons?

although it wasn't mentioned, i mainly stated what i did bsaed on seeing the most rich knock from using E85 and wanted to be clear about MY setup.. for regular pump gas and even combined with meth injection way back when, i still would see knock increase at anything richer than mid 11's for AFR.. I couldn't run in the 10's no matter what fuel over the years, even mixed fuels behaved the same.. with the exception being leaded fuels, which were a lot more tolerant to rich AFR's compared to E85.

Somewhere there's an SAE paper i linked a while back that explains both the rich adn lean burning aspcts of the fuel..the leaner it is the more timing it needs and likes, the richer it burns theless timing it needs.. I wish i knew where i linked it because i lost the copy i saved to a hard drive failure amonth or so ago, but it's something to do with the properties of alcohol and the way the flame front propogates under pressure from an ignition source point at each given A/F mixture (and what was nice was it was specific to e85 and not just ethanol alone which can be quite different in behaviour)

 

[My1GLaser]

I'm gonna throw a few things out there that I dealt with many years ago when running just pump gas and 9:1 CR pistons. Most of this wasn't necessary til I ran 22-24 psi. Not sure how much will help, but it is some ideas for you to look into.

My car would knock more when BP switched to the gas with "invigorate" in the fuel. I don't know what it is, but I switched to Exxon and the couple degrees of knock went away.

The gas stations with only one hose for all the different octanes have some 87 octane in it still when you pump. How much depends on the hose routing. If you only put a couple gallons of gas in your tank, there could be a good % of 87 in your mixture which drops your octane rating.

I ran non-projected plugs. BR7ES

Get your coolant temps down under 190*

There is a torque spec for the knock sensor...can't remember it off hand though. I think there is a gasket with it too, but I'm not 100% sure of that either. Too tight or too loose can cause bad readings.

Have you done a compression test? Did you CC the head? Were your pistons above the deck surface? What HG do you have? (trying to get an idea of the static CR and your quench)

Do you have the stock PCV setup still? Oil getting into your intake tract acts like anti-octane from what I understand.

 

[spadepro22]

Have you done a compression test? Did you CC the head? Were your pistons above the deck surface? What HG do you have? (trying to get an idea of the static CR and your quench)

Do you have the stock PCV setup still? Oil getting into your intake tract acts like anti-octane from what I understand.

I haven't done a compression test yet, Im just about to hit 500 miles on the rebuild. The motor was built by Forced Engineered. That really all I can say about the deck surface and CCing the head. It has a composite head gasket. It still does have the stock pcv setup and I run bpr7es plugs gapped to .028(just changed them yesterday).

One thing that I do notice is that when I go to shift gears and I let the rpm drop the car will stall. I have to tap the gas to rev the rmps so it doesn't cut off.

 

[My1GLaser]

Try upping the coasting FC offset to 90 or 130 to see if that helps the stall. (under the rpm tab)

Also, screw out your BISS about 3/4 to 1 turn and let your ISC come down to near 32. It helps the engine catch itself better during decel.

This is especially true with a Fidanza FW since they are so light. I know it has helped my decel stalling when coming to a complete stop. Not sure how much it will help with stalling between gears...

 

[spadepro22]

Try upping the coasting FC offset to 90 or 130 to see if that helps the stall. (under the rpm tab)

Also, screw out your BISS about 3/4 to 1 turn and let your ISC come down to near 32. It helps the engine catch itself better during decel.

This is especially true with a Fidanza FW since they are so light. I know it has helped my decel stalling when coming to a complete stop. Not sure how much it will help with stalling between gears...

I set the BISS screw, its around 32-40 hell I can't get it to say still. I upped the coasting FC offset to 130 and it seems better. With the Kelford 272, would the ICSposition be lower than 32? Just curious. Oh yea I can get my coolant temp down to 193-196 if I keep my fans running constantly(then again it was night), but is that a good idea to keep them running or should I invest in some newer slim fans?

 

[My1GLaser]

Once I hit 170*, mine pretty much run all the time.

 

[boost97gst]

Whats the ambient temp in SC? It cant be that hot. I installed a stant 170* and without any ducting,full ac, fmic all in the way and in these temps even cruising my car wont ever go above 190. Change youre tstat to a 170.

Do you have stock fans still? Both AC and passenger? That should be more than enough especially in winter even down south where you are. What happens in the summer? I bet that thing overheats bad on the highway

I would imagine with radical272s like kelfords that youre not going to see the "optimal" .25gr/rev in link. Though i do think you can get your ISC down around 50 which is fine. As long as you can run all acc like lights, stereo, AC(especially that) and the ISC can compensate then your biss is good to go. And if the Car idles where you tell it to in link settings.

 

[spadepro22]

Do you have stock fans still? Both AC and passenger? That should be more than enough especially in winter even down south where you are. What happens in the summer? I bet that thing overheats bad on the highway

Na, it never overheats in the summer time. It is around 215 highway tho. I have 2 slim fans, not sure of the brand. I'll look into the t-stat.

 

[boost97gst]

Now this is just what ive heard and read, but the brand of slims matters greatly. The spals/fals are much more eficient. Maybe some simple ducting too?

 

[spadepro22]

Hey folks, I noticed when I got the new OEM knock sensor it seem somwhat soft out of the box. I felt it today and its not gooie or anything, but its not as hard as the one that was on my old engine. Does the knock in the logs look like a problem of some other sort? Would it be a bad idea to put the old one back in or would that be a band aid?

 

[spadepro22]

Still getting 1-4 counts of knock. We added fuel yesterday and shot for 10.2 afr and the knock is still there. Very reputable tuner from this site is remote tuning and says there's no reason it should be knocking with how low the timing is. What should I do?

 

[turboglenn]

try going leaner, many have mentioned rich knock including myself,If i went anywhere near 10:1 on any fuel aside from leaded i'd be lighting a knock sensor up! Also, knock sensors aren't the be all, tell all and end all of tuning, they are only a tool to use as anidea of how teh noises in the engine are changing once you get beyond OEM power levels... I ran without one for 9 years, have acustom stand alone knock system now and i still barely pay it any mind when it's lighting up as long as it's behaving in the fashion inwhich i'm accustomed to seeingit behave...there's a strong difference between engine noise and knock.. if you were constantly knocking as bad as a DSM KS would lead you to believe you were, well, we'd all be buyinh a lot more engine parts

 

[spadepro22]

try going leaner, many have mentioned rich knock including myself

We have. Went from 10.9 to 10.2. He said if it still knocked at 10.2 its probably picking up noise, which I hope it is with only 750 miles on the rebuild.