Heak Soak
03-16-2011, 06:27 AM
#46
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That helps. The next time you start the car, look at the instruments in the upper right corner and see if you see the "Check Engine" come on. It should - along with every other light on the dash.
However, I'm starting to agree with drbob's assessment, though I've never heard anyone else experience this.
However, I'm starting to agree with drbob's assessment, though I've never heard anyone else experience this.
ETA - Perhaps it's our lovely combination of cold weather and solid traffic, along with my oversensitivity!
03-16-2011, 06:37 AM
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So, the problem appears to be rather intermittent, if I'm reading correctly. You have dyno runs which seem to be spot on. The engine is usually quite warm then. This is going to be hard to find if intermittent.
Anyway, just for completeness, the WOT switch usually works or doesn't (not intermittent) and can be tested with the Sharktuner, Porsche Hammer tool, John Speake's Hammer clone called the Spanner or Theo Jennisken's 928 Diagnostic program OR you can check it directly by getting your Ohm meter out and checking for a signal when the pedal is depressed. You would pull the plug off the LH, hook the meter up to the plug connectors 3 and 17 and look for continuity (well, spec is <10 Ohms) somewhere above 2/3rds throttle. Do the same with the EZK plug at pins 26 and 18. Many of these switches don't trip until the pedal is close to or on the floor. Some don't trip at all which may be a sign the throttle cable has too much slack or the WOT switch is broken. The WOT switch enrichens the fuel mixture and retards timing a bit when you push hard on the gas pedal. Even if you find it broken, which I would definitely fix, it may not be responsible for your complaint.
The Sharktuner certainly would provide a lot of useful information if you could log all the parameters it monitors during one of your low power episodes. However, once you find and fix the problem it wouldn't be much use to you unless you were planning some serious engine mods.
Anyway, just for completeness, the WOT switch usually works or doesn't (not intermittent) and can be tested with the Sharktuner, Porsche Hammer tool, John Speake's Hammer clone called the Spanner or Theo Jennisken's 928 Diagnostic program OR you can check it directly by getting your Ohm meter out and checking for a signal when the pedal is depressed. You would pull the plug off the LH, hook the meter up to the plug connectors 3 and 17 and look for continuity (well, spec is <10 Ohms) somewhere above 2/3rds throttle. Do the same with the EZK plug at pins 26 and 18. Many of these switches don't trip until the pedal is close to or on the floor. Some don't trip at all which may be a sign the throttle cable has too much slack or the WOT switch is broken. The WOT switch enrichens the fuel mixture and retards timing a bit when you push hard on the gas pedal. Even if you find it broken, which I would definitely fix, it may not be responsible for your complaint.
The Sharktuner certainly would provide a lot of useful information if you could log all the parameters it monitors during one of your low power episodes. However, once you find and fix the problem it wouldn't be much use to you unless you were planning some serious engine mods.
If it were running lean, perhaps it would make it more prone to preignition unless the ambient air is particularly cold?
I wasn't planning on serious engine mods, but I think I'll invest in a diagnostic tool in the near future! In the mean time, I'll have a play with an ohmeter at the weekend and see if I can reveal anything! Thanks for the help!
03-16-2011, 06:56 AM
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Thanks John, I'll definitely take you up on that! I'll give you a ring when I have the car back up here; having two 20mpg Porsches for running around in was proving a bit excessive and it's back in my parents' barn in Reigate for now!
The MAF did make a noticeable improvement though, it's generally a lot more responsive, and feels like it's pulling harder!
The MAF did make a noticeable improvement though, it's generally a lot more responsive, and feels like it's pulling harder!
03-16-2011, 09:06 AM
#50
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OK, as well as a diganostic tester we can put a SharkTuner equippped EZK ECU on that will monitor knocks in real time. It may be that the dynamic knock control is being triggered quite often.
