DavidDeco

I consistently get high (MAX) knock levels (below P10/boost) when datalogging the Advanced Set. My averages are in the 20's but I consistently get 70's to 90's in the region roughly formed by the block n8/n9 starting at p3 down to p10/p11.

My AFR are relatively low in that region 12's/13's comprable to target maps. I have tried adding lots of fuel which does seem to lower them slightly but then I'm going into the 10's/11's AFR to reduce max knock from maybe low 80's to low 70's.

This is the only region I get max knock values this high.

I started backing out all the gas I've added there because it didn't seme to do much difference. I know the knock sensor in general is not that useful but it's still I concern. I have changed the knock sensor to a new one and it still does the same pattern. It always has.

Any ideas?

David

twokrx7

iTrader: (1)

Just so you have something for comparison, I consistently get single digit knock in those same cells with AFRs in the 14's. Don't recall ever getting over 20 until I hit P15 or above at any rpm.

Have you played with timing and split? Easy test especially with the Commander as you can pull timing on the fly and quickly do multiple runs.

Here's a copy of one of my datalogs, you can see my timing, knock, and AFRs. Look at the basic knock as it is consistently higher than the advanced.

DavidDeco

[QUOTE]Originally posted by twokrx7
Just so you have something for comparison, I consistently get single digit knock in those same cells with AFRs in the 14's. Don't recall ever getting over 20 until I hit P15 or above at any rpm.

Have you played with timing and split? Easy test especially with the Commander as you can pull timing on the fly and quickly do multiple runs.

Here's a copy of one of my datalogs, you can see my timing, knock, and AFRs. Look at the basic knock as it is consistently higher than the advanced. [/QUOTE

I'll check the timing here shortly. I haven't modified it myself but I did start off basing my maps on someone else with similar mods and then using the FJO and Datalogit started tweaking fuel from there.

Thanks...my Average knock values in MAP Watch are always pretty good. It's just the MAX values in those 2 columns.

David

DavidDeco

I took a few lines where my knock shot up. Here is the
snippet....The timing doesn't seem that high. It is identical in those areas to an Initialized PowerFC. My timing was advanced in some boxes but not the area I have the issues in...


Time(S) AN1 FJO WB A/F MAPN MAPP Rpm PIM IGL IGT Knock InjFS (mS)
20.619 11.62111204 8 6 3656 6957 26 26 76 0
34.73 10.83720067 8 7 3805 7525 25 25 1 0
34.8 11.07479538 9 6 3852 7445 26 26 85 0
34.88 10.88418316 9 6 3930 7301 26 26 73 0
34.95 11.02673976 9 6 3991 7077 26 26 72 0
35.03 10.93143365 9 6 4023 6773 30 30 66 0
35.1 10.88418316 9 5 4089 6069 35 35 76 0
82.398 11.12311899 8 11 3687 12229 19 13 76 2.447999954
82.478 10.97895271 8 11 3725 12461 19 13 81 2.415999889

DavidDeco

While I'm at it...check this sequence out - all at a fixed N and P (7 & 3).

N, P, IGL, IGT, Knock, InjFS

7 3 33 33 1 0
7 3 33 33 55 0
7 3 33 33 1 0
7 3 33 33 1 0
7 3 33 33 1 0
7 3 33 33 49 0
7 3 33 33 1 0
7 3 33 33 49 0
7 3 33 33 0 0
7 3 33 33 1 0
7 3 33 33 0 0
7 3 33 33 51 0
7 3 33 33 0 0
7 3 33 33 1 0
7 3 33 33 54 0
7 3 33 33 1 0
7 3 33 33 69 0
7 3 33 33 1 0
7 3 33 33 61 0
7 3 33 33 1 0
7 3 33 33 1 0
7 3 33 33 0 0
7 3 33 33 1 0
7 3 33 33 59 0
7 3 33 33 1 0
7 3 33 33 73 0
7 3 33 33 1 0
7 3 33 33 73 0
7 3 33 33 1 0
7 3 33 33 78 0
7 3 33 33 1 0

twokrx7

iTrader: (1)

Doesn't appear to be related to the tuning, you might have some other mechanical or electrical issue.

I think that is about the rpm that the air pump cycles off? Cannot recall for sure as I have run without one for years.

What do you hear under the hood at N7, P3?

Beast From The East

My guess is you are running so rich you're still burning fuel in the downpipe, which is what your knock sensor is picking up. You should be running around stoick or a bit leaner in the na area of p8 on down, then moving towards 13.5 as you transition over to boost in p11 (or if you are under load in the na area - you can control this via your inj. accel. settings).

I was running so rich at around 15psi (after a few runs, when my turbo manifold was glowing red) back when I had sequential stock twins that the exhaust was ignitiing in my downpipe - sounded like pre-ignition but it wasn't.

Clean up your afr's in the n/a region - you should never run less than 13 or you're just wasting gas and fouling your plugs.

Beast

PS Edit - our knock sensor's don't work for crap, either. If yours is bad then who knows what kind of cacamamy numbers you'll get.

DavidDeco

Absolutley nothing. Before I ever even tuned it with the default PowerFC maps, my mechanic and I both drove it to hear for knocks because we noticed the Commander showed high peak values (no datalogit then).

I have never heard the car ping. I think I *may* have heard once under extreme stress but I was in a completely different part of the map, n117/n18's.

David

DavidDeco

Yeah I replaced the knock sensor just to be sure and same thing. It's hard to tune those areas because of fuel cut. I try to look at the logs to see where they are typically at but high AFR's on fuel cut obscure some of the low p areas. I wish the Datalogit would filter out readings during fuel cut.

I just backed off my timing a few degress in those areas and will drive it home tonight to see if there is any effect. I'm going to dyno tomorrow so I plan to make some runs tonight for further cleanup.

Thanks for the feedback to all.

Beast From The East

Rather than use the Datalogit, the best way to tune the na area is to get someone else to drive the car on the highway, use the commander, and watch your afr display from your wide band. have them drive at highway speeds 'steady state' and only change gears from third, fourth and fifth. People will look at you funny running in third at 70 mph as you try to tune the n10+, p8- areas (doesn't he know how to shift?). Once you've used the commander to dial in your na area, just read the file with datalogit and save it.

Because of fuel cut, I just try to set my avg. afr reading in the na area at p8 and below to around 15.5. That takes into account the skew caused by the fuel cut numbers. Just read the min/max in each cell and keep a mental note of what you see on your afr display. The nice thing about the na region is that it is pretty forgiving on running lean, unlike the p19 area where I like to live

Beast

DavidDeco

Lucky you, I'm stuck to p18 at best. I won't venture above 15psi with the stock turbos.

I didn't realize you could go to lean in p4-p8 as well.

I did a quick test run after retarding both timing in those areas by 2 degrees...if anything it was worse...I actually saw numbers above 100. So much for that.

I'm going to hope its not telling me something useful and just start leaning the NA areas under 9.8, .004 at a time. I do get back fire but back fire is usually limited to the low p but high ns where I accelerate really strong and then cut it.

DavidDeco

Just some followup....

I have tested the "too rich" theory and don't think it's that. Taking out fuel in those areas to get it in the high 13's has caused the previous knock to go noticeably higher. I'm not hearing crap but the datalogit is logging higher (max) values which concerns me. Of course adding tons of fuel lowers it to 60's but with AFR's really low. (10.5 and the like).

Beast From The East

There is no way you should be pinging in that area with good afr's unless your timing is so screwed up you can't even imagine.

I think your knock sensor is kaput, or it's picking up other noises unrelated to engine knock. I've always been told the stock knock sensor is **** anyways.

If you look at the log I sent you you'll notice that my knock numbers can spike over 100 in the na areas ringht before going into boost, but I'm not worried about it because I know my timing is good and my afrs were around 12.4 during the transition to boost. I think you're placing too much faith in the stock knock sensor.

Beast

Badog

I am stating the obvious to everyone on this thread, I know. It's more intended for the general viewing audience:

The knock sensor is a microphone nearer to the front housing, located below the spark plugs.

Knock values are relative to the car that they are in. Comparing the actual values between cars introduces the microphone as a variable.

One should compare the delta values between what is "normal" for each car and their high readings. Hence a delta that is >~5x what is normal would/should be reviewed.

Knock readings can be influenced by other sounds than those related to combustion.

Knock sensors do go "bad."

In "normal" situations, the peak of the knock values intersects the peak of the torque curve.

Knock values can be influences by ignition timing changes, then fuel changes.

Badog

Here is part of your log, graphically represented by a select criteria. You knock readings/range is the lowest I have ever seen. What are your mods?

Below data is normailzed for some values, (Y/MAX Y *100) where Y is each graphed criteria.