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Gruppe IB
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About carrpet

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  • Location
  • Interests
    Porsche engineering, Salmon Fishing, Golf

Previous Fields

  • Current 911
    1989 930 G50 66, K27 7200, Fabspeed Long Neck Intercooler, Fabspeed twin pipe exhaust, Classic Retrofit Ignition & Fuse board owner since 1997
  • Daily Driver
    BMW X5
  • Day Job?
  • Drink?
    Bordeaux, St. Julien, Talbot

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  1. Replacing the Porsche overboost switch with the Tameson adjustable pressure switch has 100% solved the problem of overboost "tripping" due to a switch that is designed to be used with a stock Turbocharger / stock intercooler / stock wastegate with 0.8 Bar spring combination. My stock pressure switch tripped at 1.2 Bar with my 1.0 Bar wastegate spring. The adjuster has a 3mm allen key head and is very tight so no risk of vibration changing adjustment. I set the switch to 1.5 Bar, took the car for a drive and no overboost tripping. So this device is half the price of a new Porsche switc
  2. With help from Steve from FrankenCIS it appears to be very easy ! The yellow wire from the CDI+ box remains open until the MAP rises to 240kpa (1.4 Bar) then it grounds (causing CDI+ to retard timing by 10 degrees) and remains grounded until the MAP drops to 230kpa (1.3 Bar).
  3. Hi Jonny, Thanks for responding I was thinking soft limit, on the basis that this is not a melt down condition but a response is needed which would be obvious and cause the driver to back off immediately. I am open to your thoughts on this ?? I can still retain the adjustable overboost switch as my hard cut off Peter
  4. The Porsche over boost switch turns off both fuel pumps when triggered. This is not a very healthy thing to do ie. forcing the mixture lean in a WOT full boost condition. Not really a smart thing to do !! I would prefer to trigger the soft limit in the CDI+ box so if Jonny Hart picks this up I would like find a way of using MS and the MAP sensor to trigger the soft limit in the CDI+ box (at 1.5Bar) and therefore cut ignition rather than fuel. Any thoughts on this would be most welcome !
  5. Saab have used adjustable Turbo over boost switches for years so the concept seems proven so why not give it a go ? I have identified an adjustable pressure switch which has a adjustment range of 0.2 to 2.0 Bar and a hysteresis of 5% which is very low and twice as good as the standard Porsche device at half the cost The sensor has a 10*1mm thread so should be plug and play once calibrated ! [url]https://tameson.co.uk/measurement-control/pressure/pressure-switch-and-transducer/pressure-switch/psl-b-n-0p2-2-c-fp-0p2-to-2bar-nc-brass-pressure-switch-m10-42vac-dc-flat-connector.html
  6. I have bench tested all 3 Porsche Probes using a rig which is partly my fuel pressure testing rig and partly a cylinder pressure testing rig which includes a pressure regulator. I have added a good quality 2 Bar gauge to give more granularity. I test both on the pressure increase and pressure decrease. There seems to be about 0.1 bar difference (hysteresis) on the standard sensor. The rig works so well that the continuity meter can sense just before the NC contacts open because the resistance changes just before opening. I have already tested and rejected one adjustable switch
  7. The new Porsche pressure switch had a lower (1.0 Bar) opening pressure than the existing switch. Porsche supplied a second switch (1.2 Bar) but this too opened at a lower pressure than my existing switch (1.25 Bar) . As these switches age the experience of other 930 users is that the spring "weakens" and therefore the switch would open at a lower pressure. This suggests that my original switch when installed in 1989 had an opening pressure of 1.3-1.4 Bar. Either Porsche have changed their spec or there is a defective batch out there which would not necessarily be detected with standard ageing
  8. I have now done a tuning run with Shaun of MS2Tuning services (recommended by Ian Comerford) in the passenger seat with my laptop in his lap. All went very well and I now have a good VE1 tuning map The one issue that arose though was the Turbo Over-boost Switch kept tripping, which is a very undesirable experience ! MS was registering up to 1.2 bar on the MAP sensor under full boost ! This led to some interesting diagnostics. We used Shaun's pressure test rig and measured the pressure that my "1.0 Bar" Tial was opening by injecting an increasing pressure into the control port
  9. Bluetooth connection to MS has been problematic but I haven't given up on this yet ! I have had two bluetooth serial connectors supplied by LD Performance. Both have failed. It appears that the voltage regulator was overheating and then failing. The specification claimed 5v to 15V. Mine failed at 13.9V. They gave me my money back ! I am currently working on other options using the 5v reference supply from MS which is good for up to 100mA. MS does seem to be very fussy about what it will talk to so more on that later, I hope !
  10. The Classic Retrofit CDI+ box is shipped with a Tacho sweep feature turned on. I presume the Tacho sweep is to tell you that the CDI+ box is working correctly ! Unfortunately MS interpreted the Tacho sweep as an engine start registering the increase in RPM. This wasn't very helpful for optimising start up ! Jonny Hart had warned me about this having helped someone out with a similar problem on a Pelican forum. I was able to connect with the box using the supplied USB serial 3.3v FTDI lead and disable the Tacho sweep (with help from Jonny). I also set the soft and hard rev limits s
  11. I thought you might be interested in an 8 second snapshot from turning the engine over to running as there is a lot going on in a short space of time. Pre-microsquirt it was taking about 15 seconds to fire from cold followed by a very lumpy tickover for the next 30 seconds (foot off the accelerator pedal throughout) Since then I have Installed MS which gives fantastic diagnostic capability Replaced my WUR with an eWUR Replaced my AAV with an MS controlled Idle Air Valve so I am now in full control of how much air gets bled into the inlet manifold during cranking a
  12. Now the fun begins The first stage in tuning is to generate an AFR table from the engine performance specifications. This is a reference table for the tune and represents AFR targets across the full range of RPM and MAP values. Remember I have a Turbocharger so my maximum MAP is going to be 1.8 bar or 180 kPa if I have an original turbo wastegate spring which opens at 1.8 Bar. The next tool is the Fuel VE1 table which starts life as 100% across the board. As soon as the AutoTune button is turned on, the VE1 table values are adjusted live by Tuner Studio, in the car, b
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