Sharktuning issue..
11-24-2012, 05:14 AM
#61
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Fred:
For peeps with a 90d transition right at the MAF..you pretty much need a honeycomb, that's pretty much settled MAF science there.
I run with my IC on the MAF, because it does that straightening for me.
My next steps on cleanup will be get a honeycomb for the MAF nonetheless (so I can run W/O IC as well), ceramic coat the boost pipes, fuel rails and IC, discuss my fuel damping needs with Whipple Superchargers and maybe install two of their units on the rails, finish the prototype new air filter/airbox project...and clean up wiring and the 5v source for the fuel pressure and MAP sensors, work on a better and maybe hidden Provent install.
For peeps with a 90d transition right at the MAF..you pretty much need a honeycomb, that's pretty much settled MAF science there.
I run with my IC on the MAF, because it does that straightening for me.
My next steps on cleanup will be get a honeycomb for the MAF nonetheless (so I can run W/O IC as well), ceramic coat the boost pipes, fuel rails and IC, discuss my fuel damping needs with Whipple Superchargers and maybe install two of their units on the rails, finish the prototype new air filter/airbox project...and clean up wiring and the 5v source for the fuel pressure and MAP sensors, work on a better and maybe hidden Provent install.
I'll be following your progress on this with much interest. I am now wondering whether the EIS inlet helps or hinders the air flow dynamic entering the MAF. I intend to place the stock filter back on just as to whehter it has any impact on the disproportionate knocks I am picking up at the moment.
I want to try one of those honeycomb assemblies to see if that will help dampen out the fluctuations in AFR. I am now starting to feel I understand better why Porsche set the top end AFR's as rich as they did.
For the time being you really need to richen up those gaps somehow even if it gooses the other end of the cell. Better to be rich than [dangerously?]lean- as I understand you have to go real wild [10:1?] before richness plays a major drop in power whereas going leaner than AFR14.5 will kill you proportionately. It would be interesting to see just how much the torque dips in those reddish bands- pretty spectacular I suspect.
I suspect most of us are learning a whole bunch here- I certainly am. Do keep us informed of your progress.
Best wishes
Fred
11-24-2012, 03:02 PM
#62
Rennlist Member
Thread Starter
The EIS feeds air like the stock airbox does, I felt no issues with it.
And I -cant- richen up those gaps with the setup I have now, its not possible. Its a physics issue.
And I -cant- richen up those gaps with the setup I have now, its not possible. Its a physics issue.
11-26-2012, 06:30 PM
#63
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Thread Starter
Talked to Whipple..and they said mostly what I expected.
Put the fuel system back the way it used to flow, the problem will should significantly away.
Put the fuel system back the way it used to flow, the problem will should significantly away.
11-29-2012, 09:14 PM
#64
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Hey Jeff
I missed this one. You should have sent me a link. I haven't been on Rennlist much lately, been too busy with projects and work.
I will do a few plots on my car tonight & tomorrow and see if mine does it also. I am running pretty much the exact same setup as you right now with the intercooler and 70mm pulley. Haven't noticed it on mine at all, but then I usually don't drive like that. I'll post it tomorrow afternoon.
Have
I missed this one. You should have sent me a link. I haven't been on Rennlist much lately, been too busy with projects and work.
I will do a few plots on my car tonight & tomorrow and see if mine does it also. I am running pretty much the exact same setup as you right now with the intercooler and 70mm pulley. Haven't noticed it on mine at all, but then I usually don't drive like that. I'll post it tomorrow afternoon.
Have
11-30-2012, 07:09 AM
#65
Rennlist Member
Are you maxxed out on those specific cells? Appreciate you just may not be able to get fuel flowing at the peak resonance zones.
The only thing you can do with resonance is to tune the problem out of the operating zone- basic law of physics.
What will be interesting here is to know why you are experiencing this problem and others [?] seemingly are not?
My problems are quite different but I am applying the principle of elimination [what I was alluding to] to determine the cause.
In my case it boils down to either weak fuel, worn engine, poor design causing oil to lift at high rpm's, elevated inlet air temps or a combo of the above but it is a completely different problem albeit I see those troughts in just the same way but away less pronounced- on Sharkplotter it shows as vertical blue bands up to about 50% load.
Regards
Fred
11-30-2012, 11:26 AM
#66
Rennlist Member
Fred,
Your problems are different, and I don't think apply here.
If you look at Jeff's SP plot in post #1, or the plot that I posted in post #34, you will red "lean stripes" that are very narrow, and continue (and get worse) into the high-load areas.
In Jeff's case the "lean stripe" only covers a small part of each cell. There is plenty of headroom to add fuel, but then you wind up with cells that are very rich everywhere except in those "lean stripes" (in this case "rich" being 11:1 when I tried it). Now certainly rich is better than lean, especially under load, and short-term that is what he should do. But that's a pretty big compromise.
In this case it looks like a fuel-pressure issue. When I picked out a series of points that looked like constant accleration, the MAF load plotted as a straight line (post #34 above) which means that it does not appear to be related to MAF or airflow. The other side of the "air/fuel" equation is fuel, and the current working theory is that the resonance is in the fuel system. The fuel rails on Jeff's car are also modified to fit the S/C-- both rails dead-ended and one damper eliminated-- which fits that theory. So I think the plan is to get the fuel system looking more conventional/stock and see if that resolves the issue.
If you are still having problems with your car, let's discuss it in a different thread-- maybe in the Sharktuner or Sharkplotter thread. You sent some log files, but that was a while ago. Email some recent ones if you can (support at sharkplotter dot com) and I'll post some pretty pictures that we can discuss.
Cheers, Jim
Your problems are different, and I don't think apply here.
If you look at Jeff's SP plot in post #1, or the plot that I posted in post #34, you will red "lean stripes" that are very narrow, and continue (and get worse) into the high-load areas.
In Jeff's case the "lean stripe" only covers a small part of each cell. There is plenty of headroom to add fuel, but then you wind up with cells that are very rich everywhere except in those "lean stripes" (in this case "rich" being 11:1 when I tried it). Now certainly rich is better than lean, especially under load, and short-term that is what he should do. But that's a pretty big compromise.
In this case it looks like a fuel-pressure issue. When I picked out a series of points that looked like constant accleration, the MAF load plotted as a straight line (post #34 above) which means that it does not appear to be related to MAF or airflow. The other side of the "air/fuel" equation is fuel, and the current working theory is that the resonance is in the fuel system. The fuel rails on Jeff's car are also modified to fit the S/C-- both rails dead-ended and one damper eliminated-- which fits that theory. So I think the plan is to get the fuel system looking more conventional/stock and see if that resolves the issue.
If you are still having problems with your car, let's discuss it in a different thread-- maybe in the Sharktuner or Sharkplotter thread. You sent some log files, but that was a while ago. Email some recent ones if you can (support at sharkplotter dot com) and I'll post some pretty pictures that we can discuss.
Cheers, Jim
11-30-2012, 01:03 PM
#67
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plot
I combined 3 plots with 2, 1/2 hour drives this morning and this is what I get. I don't seem to have any waves in mine. Am I supposed to turn off the o2 adjust or run in not cat mode or anything like that to see it?
I wonder if it could be your new cams, when did you start to notice this?
The only thing I noticed on mine is the tipin lean when I shift gears. My car cruises around 2400rpms when I'm doing 80 on the highway, but I kept going back and forth, with light throttle, from 70 to 100 to vary the rpms. And a few times I put it in forth and went from 50 to 100 also.
I wonder if it could be your new cams, when did you start to notice this?
The only thing I noticed on mine is the tipin lean when I shift gears. My car cruises around 2400rpms when I'm doing 80 on the highway, but I kept going back and forth, with light throttle, from 70 to 100 to vary the rpms. And a few times I put it in forth and went from 50 to 100 also.
Last edited by victor25; 11-30-2012 at 01:52 PM.
11-30-2012, 01:43 PM
#71
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The trouble with this theory is that the lean-stripe at 800 is actually around 900, and 1600 is either not there or very weak. The 2400 stripe is quite sharp and sure looks like resonance, as does 3600-- but that last stripe is actually at 3400, not 3600.
I still like the resonance theory, but I am not sure how to fit it with that data.
OK, so it is not a transient phenomenon. As Tuomo said, if it is intake-related then it should change if the flappy is open, or closed--- you can change that in ST (if the flappy is connected). Or disconnect the solenoid and either connect the vacuum full-time, or not at all, for testing.
A big problem here is too many changes and not enough data.
But even a stock setup shows some signs of resonance... here is a plot from our S4 from a couple of years ago with lots of data points. You can see a weak resonance every 300-400 RPM or so. I make resonance lines at 1330, around 1550, 1815, weakly at 2100, 2300, 2660, 3050 and a broad area around 3200 (picking RPM's off the SP plot with the cursor). In this case it only happens at light loads (flappy not active?) and isn't nearly as sharp. And doesn't always show, some days it is not there at all. I've seen this effect on other cars as well, including our GT-- which interestingly went away completely when we got rid of the MAF (with no other intake changes).
Attachment 681619
I still like the resonance theory, but I am not sure how to fit it with that data.
OK, so it is not a transient phenomenon. As Tuomo said, if it is intake-related then it should change if the flappy is open, or closed--- you can change that in ST (if the flappy is connected). Or disconnect the solenoid and either connect the vacuum full-time, or not at all, for testing.
A big problem here is too many changes and not enough data.
But even a stock setup shows some signs of resonance... here is a plot from our S4 from a couple of years ago with lots of data points. You can see a weak resonance every 300-400 RPM or so. I make resonance lines at 1330, around 1550, 1815, weakly at 2100, 2300, 2660, 3050 and a broad area around 3200 (picking RPM's off the SP plot with the cursor). In this case it only happens at light loads (flappy not active?) and isn't nearly as sharp. And doesn't always show, some days it is not there at all. I've seen this effect on other cars as well, including our GT-- which interestingly went away completely when we got rid of the MAF (with no other intake changes).
Attachment 681619
Air has a much much greater ability for resonance lie this than liquid, Yes? Ask the old golden gate bridge.
Also I don't use the flappy valve, it's disconnected, while yours is connected to a vac line right?
11-30-2012, 01:45 PM
#72
Rennlist Member
Fred,
Your problems are different, and I don't think apply here.
Now certainly rich is better than lean, especially under load, and short-term that is what he should do. But that's a pretty big compromise.
The other side of the "air/fuel" equation is fuel, and the current working theory is that the resonance is in the fuel system. The fuel rails on Jeff's car are also modified to fit the S/C-- both rails dead-ended and one damper eliminated-- which fits that theory. So I think the plan is to get the fuel system looking more conventional/stock and see if that resolves the issue.
If you are still having problems with your car, let's discuss it in a different thread-- maybe in the Sharktuner or Sharkplotter thread.
Cheers, Jim
Your problems are different, and I don't think apply here.
Now certainly rich is better than lean, especially under load, and short-term that is what he should do. But that's a pretty big compromise.
The other side of the "air/fuel" equation is fuel, and the current working theory is that the resonance is in the fuel system. The fuel rails on Jeff's car are also modified to fit the S/C-- both rails dead-ended and one damper eliminated-- which fits that theory. So I think the plan is to get the fuel system looking more conventional/stock and see if that resolves the issue.
If you are still having problems with your car, let's discuss it in a different thread-- maybe in the Sharktuner or Sharkplotter thread.
Cheers, Jim
Fully agree with all you state - my original comment was that what Jeff is seeing is an extreme version of what naturally seems to occur on stock engines if one leans off and then some. Independently of this thread I was looking at this characteristic as perhaps indicative of something wrong in my set up but clearly not.
My problems are different as I have stated but even simple mods may have more consequences than we realise.
Much as I like Victor's kit, I was instinctively a bit wary of the mods to the fuel system but equally convinced he would have spotted this phenomena- his latest post above proves the point [great mapping Victor] so this begs the question what is causing this specific problem.
That Jeff appears to be the only one suffering from this phenomena is what intrigues me.
The analogue here is the approach to resolution- working backwards through the differences.
In my case I have got about as far as I can and intend to write up my work in the ST thread shortly for those interested.
Regards
Fred
