Porsche Boxster

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Porsche Boxster

Postby needspeed6 » Fri Aug 05, 2016 8:32 pm

I'm having an issue with a 2002 2.7 litre Porsche Boxster. First start in the morning the engine runs fine for 5-6 secs then starts to run poorly. The engine revs drop, it sounds like its back firing into the inlet manifold. It sometimes can stall. This situation continues for about 20-30 secs then engine returns to normal running. Vehicle can then be started and driven without issue until engine temp drops. I have started the engine with air mass sensor disconnected and it runs fine. I replaced sensor with no change to cold start. Has anyone come across a similar situation in there workshops. I would appreciate any input regarding this problem.
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Re: Porsche Boxster

Postby STC » Mon Aug 08, 2016 8:28 pm

Does this have VVT
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Re: Porsche Boxster

Postby needspeed6 » Tue Aug 09, 2016 12:21 am

Yes it does. One more unusual happening over weekend. Start vehicle wait till it starts rough running, switch off, restart and engine run fine. Repeated process 3 mornings in a row with same result.
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Re: Porsche Boxster

Postby STC » Tue Aug 09, 2016 4:17 pm

Something must change in actual values from when it runs rough and runs well.
O2S1, injection durations, temperature readings secondary ignition......

STFT, LTFT ??

Is it sensing the fault and throwing a substituted value(s) to the scantool?
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Re: Porsche Boxster

Postby needspeed6 » Tue Aug 09, 2016 8:43 pm

Injector duration increases dramatically when the engine poorly, around 14-15 ms.
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Re: Porsche Boxster

Postby STC » Thu Aug 11, 2016 9:53 pm

needspeed6 wrote:Injector duration increases dramatically when the engine poorly, around 14-15 ms.


So it is screaming for more fuel. Graphing Injector Duration, O2S1B1 & O2S1B2, Temp Sensor, MAF, MAP PID's looking to see if it is going lean and the durations rising, differences in the 2 banks then when it is running better, are the O2's working properly. Can you force them rich and lean

VVT Values ? Perhaps paralyse VVT. When its bad, introduce sniff or propane into it, does it improve it ?

Sticking with basics, Fuel Pressure and Flow ? Fuel Filter ? Amp clamp on fuel pump (Voltage Confirmed)
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