knock issues

speedjunkie · 08-04-2009, 04:46 PM

A bit of backstory first...I rebuilt the engine (streetported btw) Mar 08, at that time I installed FJO injector driver, Innovate wideband, GReddy Ti exhaust (which was EXTREMELY loud with no resonator), HKS Twin Power, Power FC, Noltec engine mounts, SARD FPR, MOCAL dual oil coolers, SS braided OMP lines, HKS Circle Earth grounding kit, Odyssey PC680 battery, brand new engine wiring harness, APEX'i AVC-R, deleted all emissions...I think alot of those things probably don't matter, but for the sake of explaining my problem...

I noticed that my knock was pretty high. Last summer I did a single turbo swap and had the car tuned. My knock sensor was pretty worn out and the tuner told me to get a new one so I did. The new one gave me low numbers at idle, but under throttle they were still shooting up (I don't remember how high specifically or under exact conditions, I'll look later), so we decided to tune using AFR and EGT. After we tuned, I had a resonator welded in because it was just too damn loud without it. It cut the noise A LOT.

I just swapped in a 500R from A-Spec, and I've been talking to Ari Yallon about tuning it. I'm adding water (with a bit of methanol) injection to help with reliability also. I explained my problem with knock and how we previously tuned using AFR and EGT, and he said we could do that but it wouldn't give us the wiggle room to feel comfortable pushing it to the limits, and if I want to tune with water injection I really need to have my knock under control anyway.

Last year during tuning, my thoughts were that since our sensors are so sensitive, maybe the exhaust vibrations were causing the high knock, but I'm not so sure. I still have to get exact numbers and conditions and I'll post them up, and I'm also going to have someone tap lightly on the engine at idle and see how high the knock goes. Oh, the car has been running pretty much pig rich the whole time, so I highly doubt I'm getting detonation, or even close. I mean seriously, since Mar 08 my AFRs have been hovering around high 9s to low/mid 11s.

As far as I can tell there isn't anything rattling though. Any ideas?

Mobius · 08-04-2009, 05:56 PM

I'm not even sure what the knock values are for a stock motor, but I have the same situation. My knock sensor reads low (good) at idle, but it reads around 3/4 of a full bar on the PFC commander under both cruise and WOT. It never exceeds this 3/4. I'm also running very rich (low 8's under load, as I've only had time to tune idle and cruise so far).

From what I've been reading, every motor is a little reads a little different (especially modified) and with the stock sensor you have to 'learn' what is a safe reading and what isn't. I don't know what the truth to this is though.

To solve your problem, so you don't have to rely on tuning with the stock sensor, rent/borrow/buy a 'knock box'. Then you can tune without worry, and also find out what is normal for your sensor.

http://www.theknockbox.cc/content/view/5/5/

Brent · 08-04-2009, 07:09 PM

What kind of knock numbers are we talking here? We talking 50's? 90's?

speedjunkie · 08-05-2009, 12:06 AM

Quote:

Originally Posted by Mobius

I'm not even sure what the knock values are for a stock motor, but I have the same situation. My knock sensor reads low (good) at idle, but it reads around 3/4 of a full bar on the PFC commander under both cruise and WOT. It never exceeds this 3/4. I'm also running very rich (low 8's under load, as I've only had time to tune idle and cruise so far).

From what I've been reading, every motor is a little reads a little different (especially modified) and with the stock sensor you have to 'learn' what is a safe reading and what isn't. I don't know what the truth to this is though.

To solve your problem, so you don't have to rely on tuning with the stock sensor, rent/borrow/buy a 'knock box'. Then you can tune without worry, and also find out what is normal for your sensor.

http://www.theknockbox.cc/content/view/5/5/

Holy shit, low 8s?! That's SUPER low.

Ok cool, I'll check out the knock box. I know our stock sensors are pretty bad about crying wolf, so I'll check this out. Thanks!

Quote:

Originally Posted by Brent

What kind of knock numbers are we talking here? We talking 50's? 90's?

I don't know the exact numbers yet, but the bar looks to be all the way across at cruise AND wot, so I'm gonna say AT LEAST 90s

. I'll have to adjust it to read numbers instead and then I'll get back to you.

SPICcnmFD · 08-05-2009, 08:16 AM

I think you should be able to read the number on the PFC, try different monitor setting like 2 4 or 8.

Also the main thing is that it reads consistant, some engines read higher than others, plus some mods such as solid mounts may make it read higher.

speedjunkie · 08-05-2009, 08:33 AM

Yeah I just forgot how to do it, I guess hitting the 'right arrow' button while it's under throttle to datalog it and it holds the highest reading IIRC.

That's true, consistency is important. I mean, I know it's not knock, but my problem is to prove that to Ari haha.

Brent · 08-05-2009, 11:08 AM

yes, hitting the right arrow records the peak number. I always keep my setting on the 4 monitor screen so I can see real time and peak.... plus if it's in 8, it's too small for me to easily read while going down the road.

Haven't people seen chatter from running extremely rich?

SPICcnmFD · 08-05-2009, 12:16 PM

I did have high knock running extremely rich, it seems to stay about the same after 10:1 or so up until whatever you tune it for.

If it does the exact same thing every pull even though you are changing the afr's and timing I don't see why that wouldn't be enough to prove it isn't knock. I know I worried because my new engine read a good bit higher than the old engine, but it reads the same every pull at pretty much any psi. I've tried richer/leaner/more and less timing to see if I could get it to change, without going to the extremes, and I get nothing. So unless it changes it's just noise from something else.

speedjunkie · 08-05-2009, 02:22 PM

Quote:

Originally Posted by Brent

yes, hitting the right arrow records the peak number. I always keep my setting on the 4 monitor screen so I can see real time and peak.... plus if it's in 8, it's too small for me to easily read while going down the road.

Haven't people seen chatter from running extremely rich?

Ok I'll try that.

Define chatter, haha. For the record, I'm not crazy about running rich, but I would consider that better than running lean haha.

Quote:

Originally Posted by SPICcnmFD

I did have high knock running extremely rich, it seems to stay about the same after 10:1 or so up until whatever you tune it for.

If it does the exact same thing every pull even though you are changing the afr's and timing I don't see why that wouldn't be enough to prove it isn't knock. I know I worried because my new engine read a good bit higher than the old engine, but it reads the same every pull at pretty much any psi. I've tried richer/leaner/more and less timing to see if I could get it to change, without going to the extremes, and I get nothing. So unless it changes it's just noise from something else.

AFAIK it's been reading the same levels of knock before AND after tuning. If I have time tonight I'll take the car for a spin and see what my knock levels are exactly, under different speeds/rpms etc and post up results. Unfortunately my laptop with my tuning map on it took a shit while I was deployed, AGAIN, so I can't do any adjustments or anything.

I have no idea what my old engine had for knock because I didn't have my PFC installed at that time. I wish I knew. Oh and I forgot to mention this last time, I'm not sure how much harder the Noltec mounts are than stock mounts, so I don't know how much of a factor that is either. I imagine the problem is between the mounts and exhaust, and who knows what else.

I have a friend here that has ALMOST a completely stock car (exhaust is RB I think, stock mounts and just switched to BNR stage 3 non-sequential) and his knock is almost non-existent, at least it used to be on his stock twins, I'm not sure what it is now. Probably didn't change.

speedjunkie · 08-05-2009, 08:11 PM

OK my roommate and I took it for a spin. At first I just revved up to different RPMs while just sitting there, to see the change...all the while sitting still AFRs never left the 10s, mid to high 10s usually. Here are our findings...

940 RPMs - 2 knock
2200 RPMs - 73 knock
3000 RPMs - 101 knock
4000 RPMs - 80 knock

Then while driving, we found pretty much the same results. I can't say its 100% consistent because at some points it may drop from 100 to 40 but it goes right back up. Since putting the new turbo, equal length manifold and CJM fuel rails on last week, I still have just about the same AFRs. At idle they're the same, around 10. Once I start moving from a stop, they will go up to around 12, sometimes getting up to 13 or 14 under light throttle and just a very little area, then it will go back down to 12, then 11, then 10, and will vary between 10 and 12. When it hits 14, I'll either give it just a little more gas or let off just a little and the AFRs will drop instantly.

The thing I need to make clear is these knock readings have been this way ever since I built this engine and put it in...with stock twins, then the first single turbo and now this one. However, I did put in the PFC, Noltec mounts and GReddy Ti exhaust when I did the engine, and since I didn't have the PFC before that it's impossible to know what it was on the old engine with stock mounts and exhaust.

SPICcnmFD · 08-06-2009, 07:36 AM

If you have some logs you can look at the graph and prove it, but if not I'm not sure you can prove it from the last setup to this one. The only thing I really know to go by is if you logged some now and changed the afr and timing and proved they were consistent, even though they are high.

Peak is hard to look at also IMO just because it can spike in one spot and then be low through the rest of the rpm range. Mine stays around 10-15 at cruise, then spikes to around 55-60 right at seq. transition then holds around 30 the rest of the way up. I've done everything I can think of to make it not spike but it hasn't helped.

speedjunkie · 08-06-2009, 09:09 AM

Well my laptop that crashed has my map on it, so until I get that fixed I can't really make any adjustments and see if there's a change. I want to do that though, that would really prove it. And the guy that tuned my car last year just moved to IL. I really need to get my laptop fixed.

Mine was spiking and then settling too alot of the time, so I see what you're saying there.

08-04-2009, 04:46 PM	#1
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO Posts: 2,089 Rep Power: 20	knock issues A bit of backstory first...I rebuilt the engine (streetported btw) Mar 08, at that time I installed FJO injector driver, Innovate wideband, GReddy Ti exhaust (which was EXTREMELY loud with no resonator), HKS Twin Power, Power FC, Noltec engine mounts, SARD FPR, MOCAL dual oil coolers, SS braided OMP lines, HKS Circle Earth grounding kit, Odyssey PC680 battery, brand new engine wiring harness, APEX'i AVC-R, deleted all emissions...I think alot of those things probably don't matter, but for the sake of explaining my problem... I noticed that my knock was pretty high. Last summer I did a single turbo swap and had the car tuned. My knock sensor was pretty worn out and the tuner told me to get a new one so I did. The new one gave me low numbers at idle, but under throttle they were still shooting up (I don't remember how high specifically or under exact conditions, I'll look later), so we decided to tune using AFR and EGT. After we tuned, I had a resonator welded in because it was just too damn loud without it. It cut the noise A LOT. I just swapped in a 500R from A-Spec, and I've been talking to Ari Yallon about tuning it. I'm adding water (with a bit of methanol) injection to help with reliability also. I explained my problem with knock and how we previously tuned using AFR and EGT, and he said we could do that but it wouldn't give us the wiggle room to feel comfortable pushing it to the limits, and if I want to tune with water injection I really need to have my knock under control anyway. Last year during tuning, my thoughts were that since our sensors are so sensitive, maybe the exhaust vibrations were causing the high knock, but I'm not so sure. I still have to get exact numbers and conditions and I'll post them up, and I'm also going to have someone tap lightly on the engine at idle and see how high the knock goes. Oh, the car has been running pretty much pig rich the whole time, so I highly doubt I'm getting detonation, or even close. I mean seriously, since Mar 08 my AFRs have been hovering around high 9s to low/mid 11s. As far as I can tell there isn't anything rattling though. Any ideas?

08-04-2009, 05:56 PM	#2
Mobius Rotorhead Join Date: May 2008 Location: Drumheller, Alberta Posts: 164 Rep Power: 18	I'm not even sure what the knock values are for a stock motor, but I have the same situation. My knock sensor reads low (good) at idle, but it reads around 3/4 of a full bar on the PFC commander under both cruise and WOT. It never exceeds this 3/4. I'm also running very rich (low 8's under load, as I've only had time to tune idle and cruise so far). From what I've been reading, every motor is a little reads a little different (especially modified) and with the stock sensor you have to 'learn' what is a safe reading and what isn't. I don't know what the truth to this is though. To solve your problem, so you don't have to rely on tuning with the stock sensor, rent/borrow/buy a 'knock box'. Then you can tune without worry, and also find out what is normal for your sensor. http://www.theknockbox.cc/content/view/5/5/ __________________ \|\|\| Never argue with idiots. They will bring you down to their level and beat you with experience. \|\|\|

08-04-2009, 07:09 PM	#3
Brent Sua Sponte Join Date: Feb 2008 Location: Killeen, TX Posts: 839 Rep Power: 18	What kind of knock numbers are we talking here? We talking 50's? 90's? __________________ Road Atlanta August 2011 NASA TT 1:33 http://www.youtube.com/watch?v=IFY00PAK_Ps Traqmate's video of my car from the 2011 UTCC at VIR http://www.youtube.com/watch?v=2Zcn6...layer_embedded Video of Yellow LS1 FD at NASA TT at VIR http://www.youtube.com/watch?v=e6k0lJkcwrM

08-05-2009, 08:16 AM	#5
SPICcnmFD Rotary Fanatic Join Date: Feb 2008 Location: B'ham, AL Posts: 329 Rep Power: 18	I think you should be able to read the number on the PFC, try different monitor setting like 2 4 or 8. Also the main thing is that it reads consistant, some engines read higher than others, plus some mods such as solid mounts may make it read higher. __________________ 1993 Rx-7 SM2 #11 At the local AutoX: http://www.youtube.com/watch?v=9VOSQkkSLQs Speed for Sale shootout 2007: http://www.youtube.com/watch?v=JiqlyAkGmpg A few laps at Barbers: http://www.youtube.com/watch?v=6_h5q...x=0&playnext=1

08-05-2009, 11:08 AM	#7
Brent Sua Sponte Join Date: Feb 2008 Location: Killeen, TX Posts: 839 Rep Power: 18	yes, hitting the right arrow records the peak number. I always keep my setting on the 4 monitor screen so I can see real time and peak.... plus if it's in 8, it's too small for me to easily read while going down the road. Haven't people seen chatter from running extremely rich? __________________ Road Atlanta August 2011 NASA TT 1:33 http://www.youtube.com/watch?v=IFY00PAK_Ps Traqmate's video of my car from the 2011 UTCC at VIR http://www.youtube.com/watch?v=2Zcn6...layer_embedded Video of Yellow LS1 FD at NASA TT at VIR http://www.youtube.com/watch?v=e6k0lJkcwrM

08-05-2009, 08:33 AM	#6
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO Posts: 2,089 Rep Power: 20	Yeah I just forgot how to do it, I guess hitting the 'right arrow' button while it's under throttle to datalog it and it holds the highest reading IIRC. That's true, consistency is important. I mean, I know it's not knock, but my problem is to prove that to Ari haha.

08-05-2009, 12:16 PM	#8
SPICcnmFD Rotary Fanatic Join Date: Feb 2008 Location: B'ham, AL Posts: 329 Rep Power: 18	I did have high knock running extremely rich, it seems to stay about the same after 10:1 or so up until whatever you tune it for. If it does the exact same thing every pull even though you are changing the afr's and timing I don't see why that wouldn't be enough to prove it isn't knock. I know I worried because my new engine read a good bit higher than the old engine, but it reads the same every pull at pretty much any psi. I've tried richer/leaner/more and less timing to see if I could get it to change, without going to the extremes, and I get nothing. So unless it changes it's just noise from something else. __________________ 1993 Rx-7 SM2 #11 At the local AutoX: http://www.youtube.com/watch?v=9VOSQkkSLQs Speed for Sale shootout 2007: http://www.youtube.com/watch?v=JiqlyAkGmpg A few laps at Barbers: http://www.youtube.com/watch?v=6_h5q...x=0&playnext=1

08-05-2009, 08:11 PM	#10
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO Posts: 2,089 Rep Power: 20	OK my roommate and I took it for a spin. At first I just revved up to different RPMs while just sitting there, to see the change...all the while sitting still AFRs never left the 10s, mid to high 10s usually. Here are our findings... 940 RPMs - 2 knock 2200 RPMs - 73 knock 3000 RPMs - 101 knock 4000 RPMs - 80 knock Then while driving, we found pretty much the same results. I can't say its 100% consistent because at some points it may drop from 100 to 40 but it goes right back up. Since putting the new turbo, equal length manifold and CJM fuel rails on last week, I still have just about the same AFRs. At idle they're the same, around 10. Once I start moving from a stop, they will go up to around 12, sometimes getting up to 13 or 14 under light throttle and just a very little area, then it will go back down to 12, then 11, then 10, and will vary between 10 and 12. When it hits 14, I'll either give it just a little more gas or let off just a little and the AFRs will drop instantly. The thing I need to make clear is these knock readings have been this way ever since I built this engine and put it in...with stock twins, then the first single turbo and now this one. However, I did put in the PFC, Noltec mounts and GReddy Ti exhaust when I did the engine, and since I didn't have the PFC before that it's impossible to know what it was on the old engine with stock mounts and exhaust.

08-06-2009, 07:36 AM	#11
SPICcnmFD Rotary Fanatic Join Date: Feb 2008 Location: B'ham, AL Posts: 329 Rep Power: 18	If you have some logs you can look at the graph and prove it, but if not I'm not sure you can prove it from the last setup to this one. The only thing I really know to go by is if you logged some now and changed the afr and timing and proved they were consistent, even though they are high. Peak is hard to look at also IMO just because it can spike in one spot and then be low through the rest of the rpm range. Mine stays around 10-15 at cruise, then spikes to around 55-60 right at seq. transition then holds around 30 the rest of the way up. I've done everything I can think of to make it not spike but it hasn't helped. __________________ 1993 Rx-7 SM2 #11 At the local AutoX: http://www.youtube.com/watch?v=9VOSQkkSLQs Speed for Sale shootout 2007: http://www.youtube.com/watch?v=JiqlyAkGmpg A few laps at Barbers: http://www.youtube.com/watch?v=6_h5q...x=0&playnext=1

08-06-2009, 09:09 AM	#12
speedjunkie RCC Loves Me Not You Join Date: Mar 2008 Location: Colorado Springs, CO Posts: 2,089 Rep Power: 20	Well my laptop that crashed has my map on it, so until I get that fixed I can't really make any adjustments and see if there's a change. I want to do that though, that would really prove it. And the guy that tuned my car last year just moved to IL. I really need to get my laptop fixed. Mine was spiking and then settling too alot of the time, so I see what you're saying there.