Hot issue

[Hooker012]

I have a 99 boxster. Ok i will try to explain this to the best of my ability. When I drive the car and let it get to operating temperature. I turn it off and come back a little later it has the hardest time starting back up. If it sits for a few hours it will start up just fine. Even if I havent driven the car and its hot ouside like in the 90s it does the same thing. It does not throw me any codes or anything. I only run premium fuel in it and all that good stuff. Any good ideas would help at this time.

[Gilles]

Originally Posted by Hooker012

I have a 99 boxster. Ok i will try to explain this to the best of my ability. When I drive the car and let it get to operating temperature. I turn it off and come back a little later it has the hardest time starting back up. If it sits for a few hours it will start up just fine. Even if I havent driven the car and its hot ouside like in the 90s it does the same thing. It does not throw me any codes or anything. I only run premium fuel in it and all that good stuff. Any good ideas would help at this time.

Hooker..

Once you manage to get the engine running, does it smell like raw fuel...?

If so, IMHO you may have a sticky cold start injector, a bad thermo-time switch, or a bad temperature sensor.

.

[BYprodriver]

Originally Posted by Hooker012

I have a 99 boxster. Ok i will try to explain this to the best of my ability. When I drive the car and let it get to operating temperature. I turn it off and come back a little later it has the hardest time starting back up. If it sits for a few hours it will start up just fine. Even if I havent driven the car and its hot ouside like in the 90s it does the same thing. It does not throw me any codes or anything. I only run premium fuel in it and all that good stuff. Any good ideas would help at this time.

If your Boxster is cranking slowly when it's hot most likely you have a loose/dirty/corroded/bad ground maybe @ starter cables or the starter is going bad. If it cranks normal speed 1st guess is fuel pump. Fuel pump is cooled by the fuel so if you run low fuel level that worsens the problem.

[Frank M]

you have a heat related failure.
we do not know if it is cranking slow, has any unusual odors once started, etc.
you need to take it somewhere to have it diagnosed.
different test need to be made depending on the previous test results.
it is impossible to do over the internet, unles you want a shotgun diagnosis.

shotgun diagnosis = change this, oh it didn't fix it so now try that, on and on.

[porscherescuer]

I have the exact same issue, although it will usually start after about 10 seconds, but idles a little rough until you give it some gas. Let me know what you find out.

[Hooker012]

After a few cranks it starts runs rough and a little bit of white smoke comes out and it smells wierd. I let it idle and it evens out and baam it drives badass. I had the usual oil air sep. problem a few months ago fixed that problem. I never let the tank go past 1/4 tank. I read on the pelican site that it could also be the crank position sensor might not be working correctly after it gets hot. Just a thought... Thanks for your input guys.

[BYprodriver]

Originally Posted by Hooker012

After a few cranks it starts runs rough and a little bit of white smoke comes out and it smells wierd. I let it idle and it evens out and baam it drives badass. I had the usual oil air sep. problem a few months ago fixed that problem. I never let the tank go past 1/4 tank. I read on the pelican site that it could also be the crank position sensor might not be working correctly after it gets hot. Just a thought... Thanks for your input guys.

If your AOS let oil into intake check #2 cyl. for fouled sparkplug.

[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.

[Overdrive]

What is this "honking" you're referring to, bugman?

[bugman]

Sounds a little like a goose honking.
Release the fuel cap and the noise stops (this closes a valve in the vent line).

Regeneration valve?

First time I've seen that part name! Have you got the Part number per chance?

Cheers bugman

[bugman]

OK found it - regeneration valve is the same item as the tank vent valve.

I have already replaced this item, looks exactly the same as the item fitted to a lot of Audi's except the Porsche item has a fitted moulded pipe hence double the price!

Bosch manufactured part, could easily adapt the pipe to fit, it would save a lot of hassle trying to remove the aforementioned "P" clip on the inlet manifold.

Will also replace the fuel filter on my next visit, just for the sake of eliminating another item.

Merry Xmas Bugman:

[LAP1DOUG]

Wow, I must have missed something in this thread.

Anyway Bugman - you may want to see if any fuel lines are touching anything hot that would cause old fashioned vapor lock in the fuel lines. I used to have a 914 that was prone to that.