Any way you can post a photo of the end of the plug for #5? It'll probably tell you a lot about what's going on.

 

Umm, sorry Mike. It is the Maf.

You hit the rev limiter recently after that.

 

After what? After getting new plugs and coilpacks?

And why is it ALWAYS cylinder #5?

 

Not sure, give it time and it will show others. BTDT. I just dealt with this.

My question was when did the misfire code come up and when you noticed it had you hit the rev limiter before hand?

 

Hitting rev limiter - tough to say. I've been driving my car pretty hard since I picked it up (Friday Aug. 25) after getting the intercoolers in, 3 boost leaks fixed, changing all the plugs and replacing coil packs #1 & #5. It wass running so strong, I have been pushing it to the limit every opportunity I can find. And yes, I have been going out of my way to find those opportunities. I could have tickled the rev limit a few times in the past week. Perhaps the raised RPM limit with the 700 program isn't such a good idea? Is it the hitting of the rev limit, or is it the air flow at the rev limit that is the problem?

After a week of hard driving, it started running a little rough. Noticable only at idle. The code came on yesterday (Friday) when I was idling in my garage while cooling down the turbos.

 

Ebaker - Here's a datalog of the short term fuel trims. I extracted the data @ greater than 70% throttle & less than 5% throttle to compair.

 

Here is the corresponding O2 sensor readings for the same LOG. During 90%+ throttle, the sensors are fairly equal. At <3% throttle, the sensors are wacked. I was reading the Porsche PET file on P0305 CEL and it indicated the possability of a stuck Vario Cam and suggested doing a test with the cam at high setting and loww setting while monitoring the O2 sensors. If there was a >15% variance during 1 of the tests and >4% variance during the other, it suggested the cause of the P0305 CEL was stuck vario cam. I would be interested in any expert input here (ebaker - you qualify!) Thanks, Mike





[edit] Throttle Position > 3% is actually < 3%

 

I can't tell much from the datalog. When I had the bad MAF I reset the ECU to zero the fuel trims. I went for a casual drive with the fuel trims displayed on the laptop. The short term fuel trims (STFT) started at neg 15% or so. As I drove the ECU compensated (learned) and the long term fuel trims (LTFT) gradually became more negative. The STFT shifted toward zero. After a 12 minute drive the LTFT's were -17%. The negative LTFT would make it too lean at full power above 3000 rpm. At full power over 3000 rpm the O2 sensor logs showed way lean, due to the learned negative LTFT.
If I logged RPM, throttle opening and lamda it showed the lean condition at 3500 rpm full throttle.
Generally speaking, when the MAF goes bad or gets dirty is gives falsely high air flow readings at low loads. The ECU compensates by going negative with first the STFT then later the "learned" LTFT. Under most full throttle conditions at higher RPM the ECU switches to open loop mode. The A/F ratio is controlled by the ECU maps multiplied by the learned too lean LTFT.
This is the way I understand it, I could be wrong.

 

Change the MAF again and see what happens.

 

Ebaker - thanks for your input. I would give more REP but the box tells me I've hit my quota for you. Thanks.

 

Mark - I'm still using the old MAF I bought from you! It's been the longest lasting 1 yet. I'm hoping Todd @ EVO puts together something soon. I'm not compelled to buy another MAF. Do you have anymore used ones lying around?

 

WOW so its holding up... I don't have anymore MAFs. I hope they put something together too... I just have a feeling that it's more difficult then we all thought. Programming might be a factor as well. just guessing.

 

Zippy

Where can i get the same program you are using and what can you log with it,,,?

 

For the brave at heart I have another option to solve the Blown MAF issue. It will require someone that is good at hands on stuff. PM me for details I will be happy to share what I have.

 

I'm using this: http://www.pocketlogger.com/index.php?pid=plobdii

You can log lots of things: timing, O2 sensors, fuel trims, load, RPM, intake temp, etc. The 2 things missing are boost and AFR's. You can clear CEL codes after reading them (a code # and description is given). All you need is an old Palm Pilot, then buy the OBD2 cable and software.