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MyTurbo3.6 MyTurbo3.6 is offline
Join Date: Sep 2001
Posts: 380
First of all, I want to thank each of you for your input! Chasing these issues can be frustrating, but it helps knowing that such a wealth of expertise exists here at PP. With the amount of modifications done to the car/engine, I went into this expecting to chase issues ranging from fuel/oil leaks to wiring to sensor calibrations to vacuum leaks, etc. I was however amazed that when I turned the key for the first time to check the fuel system for leaks, the engine fired. I download a base tune provided by Michael Pickett, tweaked a few settings and had it idling in about 15 minutes. Now to work out the kinks…

Turbonut: I do have leaks between the cats and the muffler. The muffler is just barely slip fitted to the cats at this time and will be finish welded to align properly with the bumper cover. I hadn’t considered this, and will remove the muffler while tuning (just gets a little loud). BTW, very nice setup…if doing it again, I would have went COP...have always hated all the plug wires and spent a lot of time routing them away from heat and visually out of sight.

IMONBOOST: The turbos have internal wastegates and I believe that they are set the same. Both are getting vacuum from the same source. Even off of boost, I see inconsistencies from left to right. The fuel rails are identical, with equal length feed lines and exit through a single fuel pressure regulator. I did swap the sensors left to right and saw consistent results

Jpnovak: I did perform a free air calibration, but the controllers are not grounded to the same place, hadn’t considered that. When seeing 14 on one side, I will see anywhere from 11-12 on the other. I am using TunerStudio but am only logging one WB but monitoring with 2 gauges. I have switched the input to MS between the two controllers and confirmed that the gauges match what MS is receiving.

David: I was hoping that the cam timing wasn’t the issue, but will add it to the list to verify left to right. Due to the packaging constraints, pulling plugs is a real pain…I was hoping that I would not need to so soon, but am thinking this is the only way to see which plugs are getting too much/little fuel.

Sjf911: O2 sensors are after the turbos and before the cats, both sides are in the same location. I am using two techedge controllers with NTK L1H1 sensors and believe they are calibrated similarly. If I switch the controllers and sensors left to right, I am seeing the same result with the right side being richer than the left.

Jpnovak: I have not verified that the injectors are flowing the same…how would I do this? When I purchased them, they were flow matched, but that was a couple of years ago and they have been on the shelf since them. I do have two sets of injectors and I would not rule out the possibility that I may have mixed them up. I checked the resistance at each injector when I built the harness, but it would be worth checking again. They are wired left bank, right bank.

911st: My fuel rails are in parallel, fuel filter runs to a fuel log splitting to each rail and then to a single FPR

Thoughts on diagnostic steps:

1. Remove muffler to eliminate possible issues with exhaust leaks
2. Ground both WBO2 to the same place (does this need to be the same ground point as the MS ECU)
3. Use a single O2 sensor and controller and swap side to side to get baseline readings and rule out differences between WB controllers/sensors
4. Pull plugs to determine if an over/under fueling condition exists in a specific cylinder (does it matter if I pull top or bottom or do I need to look at both?)
5. Pull injectors and verify each is firing and has a reasonable spray pattern
6. Verify consistent flow across injectors (how can I do this?)
7. Verify cam timing

Since pictures are worth a thousand words...

Old 09-13-2010, 04:00 PM
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