Hot issue

[bugman]

Hello,
Having same problem in my 98 2,7 - wife has just had Porsche run the diagnostics on it, told to change the idle control valve (easily fixed by DIY clean) and to change the Tank pressure sensor on the charcoal filter assembly.

Main stealers would not clean the ICV only wanted to replace plus the pressure sensor coming to a cool 800euros.

Will DIY fix when I'm back there.

Try this before turning engine over when hot, release the fuel filler cap and then refit, try to start - if it works its the tank sensor or shut off valve in the filler neck.

See Renntech for similar items.

Good luck.

[bugman]

OK, returned from holiday - maintaining the Boxster.

Removed and cleaned the ICV, was not too badly contaminated, noticed a crack in the plastic body of the valve, but this did not leak air.
Sealed this with hot glue and self-amalgamating tape.

Checked operation of the valve using alternative power source, open and closes fine. Refit with new gasket, started up and ran fine (cold).

Hot start still a problem (Daytime temp mid to high 30's Celcius, started fine when ambient temp less than 30c.

So still suspect fuel vapourisation, so have removed and checked fuel evap canister, did find crack at base where one of the vent pipes fits, repaired and refitted.

Fuel system still honks but only once everything warmed up.

Checked connections at top of fuel tank, can't help but think there is something not sealing correctly in the fuel system, so that fuel evaporates when stopped and temp is high.

Engine starts by depressing throttle and holding just open once fired up, settles down after approx 10secs and idles ok.

The idle is much steadier after cleaning up the throttle body.

Anyone got any more suggestions (can't see it being the Crank Position Sensor as this would not suddenly work by pressing the throttle).

[BYprodriver]

The ICV idle control valve opens the throttle while starting the engine with your foot off the gas pedal so maybe it is not working when HOT.

[bugman]

I wandered if this was the case, I may be wrong here, but doesn't the ICV then open when you release the throttle which sort of negates this answer (the Throttle body is completely closed by the butterfly at idle).

So I then went back in and checked the continuity of the throttle position sensor (all OK).

Should have mentioned that the idle is OK after the 10 - 15 secs of throttle being held open.

Also when intially cranking the engine fires up for a second then dies so I am assuming (probably incorrectly) that the fuel supply rails still have some fuel in them.

I am still suspicious about the ICV but I still suspect that its the fuel supply/ventilation system that's at fault.

Cheers John

[porscherescuer]

Any update on this?

[bugman]

Update on hot start issue.
Sorry for delay in update but have not been home to play with the Boxster for several months.
Anyway replaced the Evaporation Control valve (under the left hand inlet manifold) no chance to check the hot start problem as ambient temp now lower, but still getting the honk from near the filler cap.
BTW its a pig of an assembly to change, one P clip cannot be got at (unless you remove the manifold).
I now suspect that either there is a hole in the evap/fuel filler system somewhere or even a bad seal on the filler cap itself.

[porscherescuer]

Hey Bugman. I have the answer for you. I spent forever trying to fix this issue on my 99. It is the regeneration valve. About $150 part and labor is not too bad. This fixed all of my hot start issues. The part was back ordered, so It must be somewhat common.