Yet Another High RPM Flutter...
 

Just to recap:

1. did it with oem coils
2. changed to d585 coils, still did it
3. changed spark plugs, still did it
4. exhaust and midpipe amplified the noise
5. 1st gear fills up too fast to hear it, but you can feel the slowdown for sure
6. 2nd and 3rd gear are all i can test safely, both do it
7. Loss of power as soon as the noise starts
8. no codes other than the cat code i have
9. no flashing cel
10. Uphill in first gear, hitting "fluttering" causes a dramatic loss in power

Variables
1. Does it either under load or even in neutral
2. Not necessarily at WOT, if I sit in neutral and pump the accel (aka redlining to blow flames like a newb) it does the same thing
3. Fuel level makes no difference (as in fuel pump shouldn't be overheating)

AFR Logs
Coming after work.

sub'd for interest.

Some initially thoughts:

Clean the ESS?
Different spark plug wires?
Clean Maf?
Air filter?

Too bad you have no way to monitor Fuel Pressure and AFR's

Just to see what happens try the ESS reset procedure

I can monitor AFR's through the OBD2 port with the RxDuino (shameless plug) although not as accurate as a WBAFR. Fuel pressure I unfortunately do not have a gauge but have been meaning to get one.

Plug wires were changed when i upgraded my ignition, didn't do much. Air filter was changed when I changed to the AEM intake, didn't do anything.

I can try cleaning the maf, and intend to reset the ESS.

Any chance you can log some data for us on those 2nd and 3rd gear WOT pulls?

Sure thing, I will get some AFR readings after work. Want me to hold off on a ESS reset until I grab those logs just for the sake of having data (assuming ESS reset fixes it) ?

edit: added more info to the OP.

Sure .. it might be interesting to see a before and after log of the ESS reset

So the 20 stomp didn't do a reset, it must be different for the S2's.

I couldn't get any logs today either :(.

Today i was going up a hill and was in 1st, wow, once I hit like 8500rpm the car went NO WHERE. Insane loss of power with this.

You need to repeat this but get a data log.

Hopefully you can capture: AFR, Load, LTFT, STFT, Ignition Timing, MAF G/S or Volts

will do, gunna write up some software that will log all that

Interesting...

I'm wondering if the knock sensor is picking up the " fluttering"
and interpreting it as detention, therefore retarding to timing and reducing
the injector pulse width. resulting in the lack of power you describing.


Any change in the way the engine is starting, hot or cold??

nope no change at all, starts no problem regardless of cold start or within a few mins of shut down

going out to scan and capture data on my car so we have some Reference points.

you are the man, thanks.

Digger, just to confirm, your car doesn't do this right? You have smooth revs well into the red?

Runs smooth, pulls hard all the way to red line, 8200 miles on the car.

well thats no good ... still need to get my logs, but now I am running into the "ok so if I see some anomalies, wtf could I even do"

To me that sounds like ignition misfire.

I don't have my scan tool in front of me, but you want to go to misfire monitor/misfire counts. What you do is look for which rotor has the substantially higher number.

You could also clear the counts and take it for a drive and then see which rotor had the misfire.

If it is determined one out of the two, then just start swapping ignition components like plugs, wires, coils, etc, one at a time and repeating the test until you move the misfires to the other chamber. Whatever did it is at fault.

The funny thing is that I suspected that in the past, and that is why I went the path of the d585 coils and new plugs in an attempt to not only upgrade to a more reliable (debatable) solution, but also to completely get rid of the stock ignition as a possible cause.

New d585 coils, new wires, and new plugs. No dice.

I am starting to wonder if there is a vac leak somewhere. I believe the VDI actuator kicks at around 8000rpm, maybe there is a leak in the system somewhere that is preventing this from happening and starving the engine of o2?

That's why checking the misfire counts will help you diagnose if it's a specific rotor chamber or something that affects both chambers.

Things that could affect both would be something like a vacuum leak, or a fuel pressure problem. Individual items would be like wires, plugs, maybe a fuel injector.

https://docs.google.com/spreadsheet/...FhEbTA2b0J6OEE

Alright here are some logs gents

fyi I removed the ESS and cleaned it. A little dirty, but nothing crazy. Made no difference.

Mmmmmm first of all a stock NA engine at 244 g/s at 8200 rpm
That seems odd

:dunno:

You're running way too rich

As soon as you hit OL around 5500-5700 your dropping like a stone to 11ish AFR's
That's way rich

edit --- btw did it flutter on both logs?

If you look at both logs ... around 7200-7300 you hit 11.3 afr!!! You've almost or have bottomed out the OEM O2 Wideband.
Thats RICH!

It then ... flutters and misfires and recovers when it leans out

Why is it doing this?

Maf issues?
Maf screens are not straight or missing?
Crappy Intake?
Dirty Air Filter?

Edit Edit ---
Reset the learned parameters of the ECU ... go out and do another WOT run and data log it ... I will also bet that if you haven't driven far and have not developed and Trim you're likely to not get the shutter.

At 7100 rpm your at 11.3 afr and the LTFT is _4.7 that means its adding extra fuel!

fluttered on both logs, no flames on upshift (not sure if that matters)

intake is an AEM, but it used to do this with the OEM intake.

Air filter is brand new AEM, but used to do it with the OEM filter

MAF is all that is left in question. I will have to pick up some maf cleaner tomorrow. Safe to say I should not go above 7000rpm till i resolve this?

edit:
MAF screens are there (2) in the locations denoted by the AEM instructions, again kept both screens when i had the oem intake as well.

I dont know any reset procedures for the S2 other than the age old battery pull, I will have to do that tomorrow after work. FYI last time battery was reset was about a month - month and a half ago (installed deka battery)


so the fluttering I am feeling .... is that the ECU trying to save the motor from a super rich condition??