Hello All,

When I get my 996 parked overnight or 2 or more days the idle do not get running after cranking.I need to restart 2 or 3 times to get idle running.I changed the return pressure valve but it's remain same condition.It's sounds like lack of fuel on system which I guess being solved with pressure change.I wait some time with ignition on to fill the fuel lines but there is no results.any thoughts or experiences from you with this kind of problem?thanks

 

No CEL I take it?

What MY? Early 996's come with an ICV (idle control valve). These are prone to getting all gunked up or just going bad and this can play havoc with the engine's idle.

If the engine runs fine otherwise this tends to point the finger at the ICV.

Newer models have the e-Gas system. If you have a car with the e-Gas system you can try an e-Gas calibration. Given the severity of the behavior I don't hold much hope this will help but it costs nothing.

With the key off and your foot off the gas pedal through this procedure turn the key to the 1st position. Leave it on for at least 60 seconds. After at least 60 seconds turn the key off again and leave off at least 10 seconds.

After 10 seconds the next time you start the engine the e-Gas calibration will be complete.

Does the car have a fuel filter? Some early 996's have a serviceable filter and the newer ones have one as part of the fuel pump's enclosure/housing in the fuel tank and the fuel "filter" is not serviceable.

Beyond the above the suspicion is a failing fuel pump, or a fuel pressure regulator that is failing or has a vacuum line leaking.

A fuel system check out is best left to a professional mechanic. A layman runs the risk of a gasoline fire and this can engulf the car and the garage in no time.

 

Hello!

My 996 is year 1999 M36 engine.I already replaced fuel filter a few miles ago and the car was very smooth from this time .recently when start with no idle issue during first start I 've changed the fuel pressure regulator and had no change in this issue.
the car has very low mileage ( 20k miles now) I did a overall revision fem months ago changing all filters ,spark plugs all seal orings of tubes around coil to avoid oil contamination on spark plugs and I verify the MAF butterfly when remove the filter box and it's looks very clean.
I am suspicious of some water in gasoline which can concentrate at the bottom in tank because here in Brazil all gasoline has 25% of alchool added on it .and now we are in the local winter season ,even considering the lower temperature overhere is not so low as in some places in other countries.
As you comment I am planning to clean the ICV too as soon I receive the gasket I 've already purchased.
as short time I'll add some fuel cleaner in tank to absorb any water and run to burn the fuel tank until add fresh gas again .
I think my car has no e-gas system I guess....due to the accelerator is by stell wire yet not electronic.
I'll try all your suggestions and reply as soon I get any sucess on some of those actions.
Thanks a lot for your help!

 

Any water in the gas will be absorbed by the ethanol and carried along to the combustion chambers. I doubt there is much if any water in the gasoline, though

25% ethanol is way more ethanol than these engines were designed to run with. They were designed to run with 10% (or at least have been found to be very compatible with 10% ethanol) and my info is at least in the USA oil refiners have kept the amount of ethanol at under 10% to in the 7% to 8% range.

There is some talk about upping the 10% ethanol to 15% ethanol but I do not know if Porsche has signed off on this.

Bad cold start behavior is a side effect of too much ethanol in the gasoline.

This is what I suspect is going on. The 25% ethanol/gasoline blend is just not suited to the engine. Somewhere in the owners manual Porsche offers that if one finds the engine acting up with one brand of gasoline to switch to another brand. In your case if all brands have the 25% you are pretty much out of luck, though you might find a brand may use less than 25% and thus the engine behaves better.

 

Hey Macster!
Thanks for brainstorming ....we really suffer with no options of gas w/o ethanol over here.
I am using the best premium gas available with has "only" 25% of ethanol .regular gas has 27 % or more in some cases.I add last weekend a add a can of STP fuel cleaner treatment to help some way and itīs helps ....another "trick" I am adopting is to "full the gas line " switch on and off by 3 times the ignition key to complete the line with gas coming from the fuel pump line system . Itīs works after doing that .I presume the line get empty due to alchool "vapor lock" when the engine is hot causing a empty fuel line and need to run the fuel pump to complete the line after sometime with fuel line out of gas ....Itīs works last week after this procedure...letīs see how itīs going next times.Best Regards Alfredo