I don't have the accessport logs on me at the moment so not sure on the specifics, but I believe it was immediately hitting 13's and 14's on both lambda's once it hit boost and knock counts across all cylinders. Concerning enough once I saw that in the logs I haven't run the car since. I can get specifics from the logs after work.

 

You can always check your fuel trims at light RPM (idle/1500/2500) to see if its trying to compensate for something without doing any damage to the car. It wont be able to register a boost leak but it can tell if there is a vac leak or an issue with injectors etc.

 

Ok, tested again at the throttlebody and was hearing zero leaks. Pressurized to 16psi and left it sit for about 6-7 minutes it was still holding over 10psi. I then pulled the fpr vacuum line off of the intake plenum and threw some vacuum at that with the mityvac and it held solid, making me think at the least the diaphragm on the fpr is intact. I've put everything back together and have the compressor set to about 20 psi from the turbo side tester again and I can hear and feel it leaking out the bottom of the throttle-body to plenum oring, and now a slight leak on the check valve housing again that I siliconed. Curious though now if either one of those would cause a lean condition or if at least the throttle-body leak itself would actually cause it to get richer? Suggestions on if I should go back to the stage0 non tuned flash and try to log and see if the afr's get better? Maybe just with some light RPM as su_maverick suggested? Or best to try to get a replacement check valve and TB oring ordered in and replaced first?

 

The TB o-ring is very easy to replace. It shouldnt take you longer than 20-30 minutes to do. The gasket is only about $15 at the dealership so that should be a no brainer fix.

- Boost escaping after it has been metered will cause a rich condition as the ecu is thinking more air is coming in and adding the appropriate fuel
- Air being sucked in after the MAF/MAP will cause a lean condition as it is unmetered and wont have the fuel added to it.

You should be fine at low RPM at light throttle to test out the fuel trims as your O2 sensors will be catching any light lean condition and compensating for it using the short term fuel trims. I will defer to those with more experience in this though.

 

Yeah, it would have taken little to no time to replace when I had it apart. I was getting a leak at the TB o-ring with the boost tester I made not seating well at the bottom so ended up glueing on a spare oil filter housing O-ring to the tester. Was blaming the tester maybe not being perfectly flat, but guess it actually was the TB o-ring.


Needed to move the Porsche off the lift for some other car work so took another look at the Lambda's. At idle it's holding pretty solid in the 14.5-14.7 range. Drivability still seems fine and short of installing the Cobb AP and doing some logging I probably wouldn't even think anything was wrong as it seems smooth. Went around the block and briefly gave it some throttle in 2nd. Pulled over to check the log and it immediately had knock counts accross all cylinders with a few psi of boost.


I then went back to the stage0 map. Still lean but that seemed to eliminate the knock counts almost entirely. Did 2 short logs after and they both only marked a couple cells at -2.25 on a different single cylinder each time vs stage1 map gets counts across all cylinders and they climb with the boost.


Looking at the short term fuel trims I see them fluctuate up as the boost comes on to around 1.21-1.25 for both banks.


Need to try and do some more comparing on the few logs I do have but I think for the most part under boost its consistently high 14's to low 15's with some spikes to 16. Cruising is 13's-14's and idle holds in the 14's. And both cylinder banks are pretty even on these.


I keep coming back to thinking its more a fueling issue vs tune. I'm assuming the stage1 is more aggressive with timing and fuel causing the knock counts across all cylinders where stage0 factory tune is much more reserved and is logging very few knock counts.


I'm thinking it might be worthwhile next to look at fuel filter/fpr/fuel pump. Any opinions on that being next steps vs chasing boost leak testing further?

 

If the COBB uses a Base-1 to measure the trims then that means that the ECU is compensating up in the 20-25% range. If that is the case, it means that it is trying to compensate for a lean condition which means you are getting unmetered air coming in that it is trying to add extra fuel to.

 

I've not heard of this Base-1 term. Can you expand on that?

 

Its basically like Lambda (though not sure if its the common terminology or not).

Very simple.. 1 is the base for the reading which means nothing has changed. Everything above or below that would basically be a percent so 1.22 would be 22% rather than 1.22%

Does that make sense?

 

Ah, okay.

Yes, the Cobb reports short term and long term fuel trims as a deviation from 1.00. So your description is exactly how it works.

Left middle is short term fuel trim bank 1
Left bottom is short term fuel trim bank 2

 

Total "where have you been all my life" with the Cobb AP in the Porsche platform!

 

Russ, can you post up your most recent log?

 

2 after I reverted back to stage0 and one of the logs from stage1 91octane

 

Yeah, something is up even with the Stage0. At full throttle it is seeing 16 AFR and the ECU is trying to dump fuel to correct but nothing seems to be happening. Like I said via PM, see if you can get your fuel pressure reading to see if enough fuel is getting to the injectors.

 

If you can find a used fuel pump it's pretty easy to swap. At the very least I'd make sure nothing it bleeding fuel inside the tank and swap the fuel filter if you don't know how old the one is. I *may* have a pump in a few weeks when my car comes back from Garth if needed. It was a recent eBay purchase after mine up and died not long ago but has run great. An SRM fuel system is replacing it

 

i have a walbro 465 that fits into the factory basket if you need it. replaced with a full custom system from srm